Allegro News

Allegro MicroSystems, Inc. Announces New Programmable Stepper Motor Driver IC

Tue, 08 May 2012 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. announces a new programmable stepper motor driver IC with improved programmability and diagnostics. The A4979 is a flexible microstepping motor driver with built-in translator for easy operation. It is a single-chip solution, designed to operate bipolar stepper motors in full-, half-, quarter- and sixteenth-step modes, at up to 50 V and 1.5 A. This new device is targeted at the office automation, industrial and consumer markets.

The A4979 can be controlled by simple step and direction inputs, or through the SPI-compatible serial interface. Many of the integrated features as well as diagnostic read back are programmed through the serial port.

The current regulator can be programmed to operate in fixed off-time or fixed frequency PWM, with several decay modes to reduce audible motor noise and increase step accuracy. In addition, phase current tables can be programmed via the serial interface to create unique microstep current profiles to further improve motor performance for specific applications.

Circuit protection includes cross-conduction when switching between high side and low-side drives. The outputs are protected from short circuits. Mixed decay is a key feature integrated within the device to improve low load current accuracy. Other protection includes stall detection and hot and cold thermal warnings, over temperature shutdown, and under voltage lockout.

Allegro’s A4979 is available in a 28-pin TSSOP package (suffix LP) with exposed pad for enhanced thermal dissipation.

Allegro MicroSystems, Inc. Announces New Multiple-Output Regulator for Automotive LCD Display Bias

Tue, 01 May 2012 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. announces a fixed frequency, multiple-output supply for LCD display bias. The A8601 is Automotive Grade AEC Q-100 qualified and targets infotainment applications. It has a rich feature set that includes five regulated outputs from one low-voltage supply. The device was designed to address the need for a robust, automotive solution that uses fewer components than existing solutions, while providing higher efficiency power conversions.

Its switching frequency can be either programmed or synchronized with an external clock signal between 350 KHz and 2.25 MHz, to minimize interference with AM and FM radio bands. A total of up to five output voltages are provided, from three linear regulators and two charge-pump regulators. Each output voltage can be adjusted independently. During power-up and shutdown, the outputs are turned on/off in preprogrammed sequences, to meet the sequencing requirements for specific LCD panels.

The device is extremely robust under fault modes. Short circuit protection is provided for all outputs, the boost switch is protected against over-current and over-voltage, and input disconnect protection is achieved by driving an external P-MOSFET.

The A8601 is available in a 28-pin, eTSSOP package with an exposed thermal pad to allow for operation at high ambient temperatures.

Allegro MicroSystems, Inc. Announces New General Purpose Bipolar Switch

Thu, 19 Apr 2012 00:00:00 -0500

Worcester, MA – Allegro MicroSystems announces the release of a new bipolar switch designed with a high speed chopping circuit to null out offsets and dramatically improve switching repeatability. Allegro’s A1250 is an extremely temperature-stable and stress-resistant Hall-effect, bipolar switch. This device is especially suited for operation over extended temperature ranges to +150°C. Superior high temperature performance is made possible through dynamic offset cancellation, which reduces the residual offset voltage normally resulting from device overmolding, temperature dependencies, and thermal stress. This new device is targeted at the automotive, industrial and consumer markets.

The A1250 design includes on a single silicon chip a voltage regulator, Hall-voltage generator, small-signal amplifier, chopper stabilization, Schmitt trigger, and a short-circuit-protected, open-collector output. A south pole of sufficient strength will turn the output on. A north pole is necessary to turn the output off.

An on-board regulator permits operation with supply voltages of 3.0 to 24 V. The advantage of operating at 3.0 V is that it can be used in 3 V applications or additional external resistance can be added in series with the supply pin for greater protection in applications that can supply higher voltages.

Two package styles provide a magnetically optimized package for most applications. Package type LH is a modified SOT-23W surface mount package, while the UA package is a three-lead, ultra-mini-SIP for through-hole mounting. Each package type is only available as lead (Pb) free (suffix, -T), with a 100% matte tin plated lead frame.

Allegro MicroSystems, Inc. Announces New Addition to their Family of Regulators For Satellite Receivers and LCD TV “Combo” Designs

Tue, 10 Apr 2012 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. expands their family of Low Noise Block Regulators (LNBRs) designed for satellite receivers in Set Top Boxes and LCD TVs. Allegro’s A8303 is a single channel LNBR that utilizes small ceramic capacitors (instead of electrolytic) within the boost regulator control. The end result is a lower-profile solution that is a key requirement in LCD TV designs. Furthermore, the device can provide a key output voltage setting (15.6 V) to accommodate Japan-specific design requirements.

Allegro’s latest device offers industry-leading internal protection and robustness, an integrated boost MOSFET, current sensing, and compensation which simplifies the design and minimizes components and PCB size. The A8303 has a low supply current to save energy, high level of diagnostics, and a resistor-programmed output current limit to minimize the boost inductor/diode size and costs.

The A8303SESTR-T is available in a 4 x 4 TQFN/MLP-20 package.

Allegro MicroSystems, Inc. Introduces New Single Stage Off-Line LED Driver IC Series

Thu, 05 Apr 2012 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. introduces the LC5540LD/LF single stage power factor corrected off-line LED driver IC series which is manufactured and developed by Sanken Electric Co., Ltd. in Japan. The robust functions within these single stage converters have been developed to simplify system designs. This new series is targeted at the consumer and industrial markets targeting indoor and outdoor LED lighting and off-line LED lighting applications.

The LC5540LD/LF series are quasi-resonant topology switching power supply ICs, designed for input capacitorless applications making it possible for systems to comply with the harmonics standard (IEC61000-3-2 class C). These devices incorporate separate controller and power MOSFET chips. The controller adapts the average current control method for realizing high power factors, and the quasi-resonant topology contributes to the high efficiency and low EMI noise. The rich set of protection features helps to realize low component counts and high performance-to-cost power supply.

These devices are intended for isolated designs. The incorporated MOSFET has a V_DSS(min) rating from 650 V (LC5545LD, LC5546LD, LC5546LF, and LC5547LF,) to 800 V (LC5548LD and LC5549LF). The R_DS(on)(max) is 1.1 Ω (LC5547LF), 1.9 Ω (LC5546LD and LC5546LF,) and 3.95 Ω (LC5545LD). These devices are capable of a maximum output power of 20 to 80 W on a 230 VAC supply to 16 W (LC5546LD) to 55 W (LC5547LF) on a universal supply based on the thermal rating. Note that the maximum output power can be up to 120% to 140% of this value. However, it may be limited in applications with low output voltage or short duty cycle.

This series is available in the DIP8 and TO220 packages that have been designed to protect the IC and overall system from excessive heat. Similar competitive designs on the market cannot easily detect the power MOSFET rising temperatures.

Allegro MicroSystems, Inc. Announces New 120 kHz Bandwidth, High Voltage, 3.3. V Current Sensor IC

Thu, 29 Mar 2012 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. announces an open loop Hall-effect sensor IC with near closed loop performance (in accuracy and bandwidth). Allegro’s ACS716 current sensor IC provides an economical and precise means for current sensing applications in industrial, commercial, and communications systems. The device is offered in a small footprint surface mount package that allows easy implementation in customer applications, and is optimized for 3.3 V supply operation.

The ACS716 consists of a precision linear Hall sensor integrated circuit with a copper conduction path located near the surface of the silicon die. Applied current flows through the copper conduction path, and the analog output voltage from the Hall sensor IC linearly tracks the magnetic field generated by the applied current. The accuracy of the ACS716 is maximized with this proprietary packaging configuration because the Hall element is situated in extremely close proximity to the current to be measured.

High level immunity to current conductor dV/dt and stray electric fields, offered by Allegro proprietary integrated shield technology, guarantees low ripple at output and low offset drift in high-side, high voltage applications. The voltage on the overcurrent input (VOC pin) allows customers to define an overcurrent fault threshold for the device. When the current flowing through the copper conduction path (between the IP+ and IP– pins) exceeds this threshold, the open drain overcurrent fault pin will transition to a logic low state. Factory programming of the linear Hall sensor IC inside of the ACS716 results in exceptional accuracy in both analog and digital output signals.

The internal resistance of the copper path used for current sensing is typically 1 mΩ, for low power loss. Also, the current conduction path is electrically isolated from the low voltage sensor inputs and outputs. This allows the ACS716 family of sensor ICs to be used in applications requiring electrical isolation, without the use of opto-isolators or other costly isolation techniques.

Allegro MicroSystems, Inc. Introduces New Full-Bridge PWM Microstepping Driver

Tue, 20 Mar 2012 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. introduces a new motor driver IC designed to drive one winding of a bipolar stepper motor in a microstepping mode. The outputs of Allegro’s A4975 are rated for continuous output currents to ±1.5 A and operating voltages to 50 V. Internal pulse width modulated (PWM) current control combined with an internal three-bit nonlinear digital-to-analog converter allows the motor current to be controlled in full-, half-, quarter-, or eighth-step (microstepping) modes. Nonlinear increments minimize the number of control lines necessary for microstepping. Microstepping provides increased step resolution, and reduces torque variations and resonance problems at low speed. This new device is targeted at the office automation and industrial markets with specific end applications to include printers, scanners and copiers.

Internal circuitry determines whether the PWM current-control circuitry operates in a slow (recirculating) current-decay mode, fast (regenerative) current-decay mode, or in a mixed current-decay mode in which the off-time is divided into a period of fast current decay and with the remainder of the fixed off-time spent in slow current decay. The combination of user-selectable current-sensing resistor and reference voltage, digitally selected output current ratio; and slow, fast, or mixed current-decay modes provides users with a broad, variable range of motor control.

Internal circuit protection includes thermal shutdown with hysteresis, an undervoltage monitor, and crossover-current protection. Special power-up sequencing is not required.

The A4975 is supplied in a choice of two power packages; a 16-pin dual-in-line plastic package with copper heat-sink tabs (suffix B), and a 16-lead plastic SOIC with internally fused pins (suffix LB). For both package styles, the thermally enhanced pins are at ground potential and need no electrical isolation. Both packages are lead (Pb) free, with leadframe plating 100% matte tin.

Allegro MicroSystems, Inc. Announces Off-Line Quasi-Resonant Switching Regulators

Wed, 14 Mar 2012 00:00:00 -0500

Worcester, MA - Allegro MicroSystems, Inc. announces a new series of off-line, quasi-resonant switching regulators. This new series was developed to eliminate the requirement of a dedicated power supply to the standby circuits, by reducing the input power requirement at no load to 30 mW or less for 100 VAC input and to 50 mW or less for 230 VAC. This is about one-third the requirement of conventional quasi-resonant ICs and is the lowest power consumption available on the market today.

The STR-Y6700 series is comprised of a power MOSFET and a multi-functional monolithic integrated circuit (MIC) controller designed for controlling switch mode power supplies. The quasi-resonant mode of operation, coupled with the bottom-skip function, allows high efficiency and low noise at low to high operational levels, while burst oscillation mode ensures minimum power consumption at standby. In order to sustain low power consumption under low load and in standby mode, the controller has built-in startup and standby circuits.

The compact 7-pin full mold package (TO220F-7L) reduces board space by requiring a minimum of external components, thus simplifying circuit design. This IC, including various protection functions, is an excellent choice for standardized, compact power supplies.

Allegro MicroSystems, Inc. Announces a New Dual LNB Supply and Control Voltage Regulator

Tue, 06 Mar 2012 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. announces a robust, dual –channel low-noise block (LNB) regulator with an adjustable current limit and improved diagnostics requiring minimal supply current. Intended for analog and digital satellite receivers, this dual low noise block converter regulator (LNBR) is a monolithic linear and switching voltage regulator, specifically designed to provide the power and the interface signals to an LNB down converter via coaxial cable.

Allegro’s A8299 requires few external components, with the boost switch and compensation circuitry integrated inside of the device. The features, functions, and high level of performance and robustness easily meet or exceed OEM requirements for the latest satellite set top box designs. Note this is similar to Allegro’s electrolytic capacitor-based A8297, but the A8299 adds the ability to use ceramic capacitors for an even smaller solution size.

The A8299SETTR-T is supplied in a small, low-profile 5 mm x 5 mm, 0.90 mm QFN-28 package (suffix ET).

Allegro MicroSystems, Inc. Announces New Full-Bridge PWM Motor Driver

Tue, 21 Feb 2012 00:00:00 -0600

Worcester, MA – Allegro announces a new full-bridge motor driver IC that is designed for bidirectional pulse width modulated (PWM) current control of inductive loads and is capable of continuous output currents to ±1.5 A and operating voltages to 50 V. Allegro’s A4973 has an internal fixed off-time PWM current-control circuitry that can be used to regulate the maximum load current to a desired value. The peak load current limit is set by the user’s selection of an input reference voltage and external sensing resistor. The fixed off-time pulse duration is set by a user-selected external RC timing network. Internal circuit protection includes thermal shutdown with hysteresis, transient suppression diodes, and crossover current protection. Special power-up sequencing is not required.

With the ENABLE input held low, the PHASE input controls load current polarity by selecting the appropriate source and sink driver pair. The MODE input determines whether the PWM current-control circuitry operates in a slow current-decay mode (only the selected source driver switching) or in a fast current-decay mode (selected source and sink switching). A user-selectable blanking window prevents false triggering of the PWM current-control circuitry. With the ENABLE input held high, all output drivers are disabled. A sleep mode is provided to reduce power consumption. When a logic low is applied to the BRAKE input, the braking function is enabled. This overrides ENABLE and PHASE to turn off both source drivers and turn on both sink drivers. The brake function can be used to dynamically brake brush DC motors.

The A4973 is supplied in a choice of two power packages; a 16-pin dual-in-line plastic package with copper heat-sink tabs, and a 16-pin plastic SOIC with copper heat sink tabs. For both package styles, the power tab is at ground potential and needs no electrical isolation. Each package type is available in a lead (Pb) free version (100% matte tin plated leadframe).

Allegro MicroSystems, Inc. Introduces New Wide Input Voltage Range High-Efficiency Fault Tolerant Single String LED Driver

Tue, 07 Feb 2012 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. introduces a new single-output white LED (WLED) driver designed for backlighting LCD displays for both automotive and consumer designs and the associated application, performance and protection requirements. Allegro’s A8513 integrates a current-mode boost converter with an internal power switch and one current sink. It is a robust solution for applications such as automotive infotainment, cluster, and center-stack, industrial LCD displays, portable DVD players, flatbed scanners, and LED lighting.

The A8513 can operate from a single power supply from 4.5 to 40 V, to accommodate start/stop, cold crank, and load dump requirements. A 2 MHz boost converter switching frequency allows the A8513 to operate above the AM radio band. If required, the fault flag can be used as part of a circuit to drive an external P-FET to disconnect the input supply from the system in the event of a fault. The device provides protection against output short and overvoltage, open or shorted diode, open or shorted LED pin, shorted boost switch or inductor, shorted ISET resistor, and IC overtemperature. A dual level cycle-by cycle current limit function provides soft start and protects the internal current switch against high current overloads.

Allegro’s A8513 is supplied in both eMSOP-10 and eTSSOP-16 packages. These devices will be offered in various oscillator frequencies – please contact Allegro for further details.

Allegro MicroSystems, Inc. Announces New Dual, Full-Bridge PWM Motor Driver IC

Tue, 24 Jan 2012 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. announces the release of a new dual, full-bridge PWM motor driver IC targeted at the office automation, automotive, industrial and consumer markets. Allegro’s A4970 motor driver IC utilizes a DMOS output technology that drives both windings of a bipolar stepper motor or bidirectionally controls two DC motors. Both bridges are capable of sustaining 45 V and include internal pulse-width modulation (PWM) control of the output current to 750 mA.

For PWM current control, the maximum output current is determined by user selection of a reference voltage and sensing resistor. Two logic-level inputs select output current limits of 0%, 33%, 67%, or 100% of the maximum level. A PHASE input to each bridge determines load current direction.

The device is supplied in a 24-pin surface-mount wide SOIC with two pairs of batwing leads (LB). The webbed-pin construction provides for maximum package power dissipation in the smallest possible construction. The package is lead (Pb) free, with 100% matte tin leadframe plating.

Allegro MicroSystems, Inc. Introduces a New Customer Programmable Linear Hall-Effect Sensor IC

Tue, 10 Jan 2012 10:15:00 -0600

Worcester, MA - Allegro MicroSystems, Inc. introduces a new linear Hall-effect sensor IC with a wide ambient temperature range of 40°C to 150°C. Allegro’s A1357 device is a high precision, customer programmable, Hall-effect linear IC with a pulse width modulated (PWM), current sourced (2-wire) output. The duty cycle (DC) of the PWM output signal (freq: 1 kHz) is proportional to an applied magnetic field. The device converts an analog signal from its internal Hall sensor element to a digitally encoded PWM output signal. The coupled noise immunity of the digitally encoded PWM output is far superior to the noise immunity of an analog output signal.

The BiCMOS, monolithic circuit inside of the A1357 integrates a Hall element, precision temperature-compensating circuitry to reduce the intrinsic sensitivity and offset drift of the Hall element, a small-signal high-gain amplifier, proprietary dynamic offset cancellation circuits, and PWM conversion circuitry. The dynamic offset cancellation circuits reduce the residual offset voltage of the Hall element. Hall element offset is normally caused by device over molding, temperature dependencies, and thermal stress. The high-frequency offset cancellation (chopping) clock allows for a greater sampling rate, which increases the accuracy of the output signal and results in faster signal processing capability.

The A1357 sensor IC is targeted at the automotive and industrial markets and is provided in a lead (Pb) free, 3-pin, single inline package (KB suffix), with 100% matte tin leadframe plating.

Allegro MicroSystems, Inc. Expands Family of Single and Dual Low Noise Block Supply and Control Voltage Regulators

Tue, 03 Jan 2012 00:00:00 -0600

Worcester, MA - Allegro MicroSystems, Inc. introduces the next-generation devices in a family of single and dual LNB supply and control voltage regulators designed for satellite receivers in Set Top Boxes and LCD TVs. These single and dual low noise block converter regulators (LNBR) are fully integrated linear and switching voltage regulators, specifically designed to provide the power and the interface signals to an LNB down converter via coaxial cable.

Allegro’s latest generation of devices A8295, A8297 and A8298 offer increased internal protection and robustness, an integrated boost MOSFET, current sensing, and compensation which simplifies the design and minimizes components and PCB size. All devices have a reduced supply current to save energy, improved diagnostics, and a resistor-programmed output current limit to minimize the boost inductor/diode size and costs.

The single-output A8295 is a higher current version of Allegro’s A8296 LNBR, with both devices serving the single-tuner satellite STB market. The dual-output A8297 is ideal for dual-tuner DVR models. The A8298 is a ceramic capacitor capable version of the A8295, targeted at extremely small form factor satellite tuner applications such as “super small” STB and integrated LCD televisions.

The A8295SESTR-T and the A8298SESTR-T are available in a 4 x 4 TQFN/MLP-20 package. The A8297SETTR-T is available in a 5 x 5 TQFN/MLP-28 package.

Allegro MicroSystems, Inc. Announces New Two-Wire, Hall-Effect Latch

Tue, 20 Dec 2011 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. announces a new, two-wire, Hall-effect latch that is programmed at the factory to optimize the magnetic switch point accuracy. The A1244 Hall-effect latch uses the same patented high frequency, 4-phase, chopper-stabilization technique that is used on complementary devices in this family (unipolar switches). Allegro’s advanced BiCMOS wafer fabrication process is used to achieve magnetic stability over temperature and to eliminate offset inherent in single-element devices, when exposed to harsh-application environments.

The A1244 will be offered in two package styles. The “LH” is a SOT-23W style, miniature low profile package for surface-mount applications. The “UA” is a TO-92 style, three-lead ultra-mini single inline package (SIP) for through-hole mounting.

Additionally, the A1244 will have two I_CC (low) options, similar to that of its predecessor; -I1: 5.0 to 6.9 mA, and -I2: 2.0 to 5.0 mA.

Allegro MicroSystems, Inc. Introduces New Automotive, Sensorless BLDC Controller

Tue, 06 Dec 2011 00:00:00 -0600

Worcester, MA – Allegro introduces a new three-phase, sensorless, brushless DC (BLDC) motor controller for use with external N-channel power MOSFETs that is designed for various pump, blower and cooling fan automotive applications. The motor is driven using block commutation (trapezoidal drive) where phase commutation is determined, without the need for independent position sensors, by monitoring the motor back-emf. A programmable motor start-up scheme allows the Allegro A4960 to be adjusted for a wide range of motor and load combinations.

External bootstrap capacitors are used to provide the above battery supply voltage required to drive the N-channel MOSFETs. An automatic internal bootstrap charge management scheme ensures that the bootstrap capacitor is always sufficiently charged for safe operation of the power MOSFETs. The power MOSFETs are protected from shoot-through by integrated crossover control and adjustable dead time.

Integrated diagnostics provide indication of undervoltage, overtemperature and power bridge faults and can be configured to protect the power FETs under most short circuit conditions. Detailed diagnostics are available as a serial data word or through a programmable diagnostic output. The A4960 is supplied in a 32 lead eLQFP (suffix JP). This package is available in lead (Pb) free versions, with 100% matte-tin lead frame plating (-T).

Allegro MicroSystems, Inc. Announces New Automotive High Current LED Driver IC Family

Mon, 28 Nov 2011 00:00:00 -0600

Worcester, MA — Allegro MicroSystems, Inc. announces the release of a new family of automotive-grade, high-current LED driver ICs with extensive diagnostics and protection features. The A6265, A6266 and A6267 are DC-DC converter controllers, with the A6265/A6267 configurable as either boost or buck-boost and the A6266 in boost only. All provide a programmable constant current output for driving high power LEDs in series, ensuring identical currents and uniform brightness. The devices are capable of driving up to 15 LEDs at currents of 1 A or higher based on the external logic-level MOSFET. These devices are targeted for automotive and industrial LED driver applications, in particular exterior front and rear automotive lighting.

The devices provide a robust, high performance, cost-effective solution using an external MOSFET and minimum additional external components. The maximum LED current is set with a single external sense resistor and can be modified using a current reference input. Direct PWM control is possible via the enable input, which also provides a shutdown mode. The dimming schemes for A6265 and A6267 differ slightly, offering flexibility to the designer with a choice of drop-in devices.

Integrated diagnostics and two fault outputs give indication of under voltage, chip over temperature, output open circuit, LED short circuit and LED under current and can be configured to provide short to supply and short to ground protection for the LED connections. The ability to detect one or more shorted LEDs is a unique feature of all the devices.

All three devices (A6265KLPTR-T, A6266KLPTR-T and A6267KLPTR-T) are available in a 16-pin eTSSOP package (suffix LP) with exposed thermal pad.

Allegro MicroSystems, Inc. Introduces New Automotive, Low Side MOSFET Pre-Driver IC

Tue, 11 Oct 2011 00:00:00 -0500

Allegro MicroSystems, Inc. adds a new low side MOSFET pre-driver IC to complement their existing automotive pre-driver portfolio. Allegro’s A3944 is a programmable 6 channel low side MOSFET control IC, with a 50 V rating on drain feedback inputs, making this device suitable for use in automotive diesel applications. Due to the extensive diagnostics and wide operating voltage range this new device is targeted at the automotive market; however, it may also be used in consumer and industrial applications.

Each channel is controllable by a combination of parallel and serial inputs and provides sufficient gate drive current to allow PWM control up to 10 kHz, depending on the MOSFET gate charge. Each channel provides independent fault diagnostics for short to ground and open load when in the “off state,” and short to battery when in the “on state.” A short to battery can disable the output until reset or for a programmable retry time. Each channel provides independently programmable fault thresholds and blanking times. In addition to channel state control, channel fault masking, fault thresholds and fault timers are programmed through the SPI compatible serial interface. The serial interface also provides read back of the fault status for each channel. Digital inputs and outputs are compatible with 3.3 V and 5 V supplies.

The A3944 is available in a 28-lead TSSOP (LP) package with exposed pad for enhanced thermal dissipation and is lead (PB) free with 100% matte tin plated lead frames.

Allegro MicroSystems, Inc. Announces New Full-Bridge DMOS PWM Motor Driver ICs

Tue, 30 Aug 2011 00:00:00 -0500

Worcester, MA - Allegro MicroSystems, Inc. announces the release of two devices that complement the next generation family of fully-integrated single, full-bridge motor driver ICs. Allegro’s A4952 and A4953 are designed for use in brush DC motor drive applications and are rated for peak output currents to ±2 A, and operating voltages to 40 V. Input terminals are provided for use in controlling the speed and direction of a DC motor with externally applied PWM control signals. Both devices feature internal fixed off-time PWM where the maximum current can be adjusted by the user’s selection of an optional sense resistor and the voltage applied to a VREF pin.

Internal synchronous rectification control circuitry is provided to lower power dissipation during PWM operation. Internal circuit protection includes overcurrent protection (OCP), motor lead short to ground or supply, thermal shutdown with hysteresis, under voltage monitoring of VBB, and crossover current protection. The A4952 includes a FAULT pin and the ability to change the behavior of the OCP latch based on the logic level applied to the RTRY pin. These devices are primarily targeted at the office automation market; however, they are also suitable for commercial and industrial applications requiring a brush DC motor driver IC.

The A4952ELYTR-T is available in a 10-pin MSOP package and the A4953ELJTR-T is available in an 8-pin SOICN package. Both packages feature an exposed pad for enhanced thermal dissipation and are lead (PB) free with 100% matte tin plated lead frames.

Allegro MicroSystems, Inc. Announces New Automotive Grade Three Phase MOSFET Pre-Driver IC

Tue, 26 Jul 2011 00:00:00 -0500

Worcester, MA – Allegro announces a new automotive grade three phase MOSFET pre-driver IC targeted at BLDC motors commonly found in electronic power steering systems, engine cooling fans, transmission actuators and hydraulic pumps. Allegro’s A4933 is primarily targeted at extreme applications where high power, high torque and high temperature combine to require a MOSFET pre-driver that is able to deliver large MOSFET gate drive and switching capabilities.

The A4933 is targeted towards three-phase systems, and in particular, is most often adopted in systems which use sinusoidal control of the motor phase currents. This commutation method provides smooth operation, which reduces audible noise and mini¬mizes torque ripple at the load. Key features include: an integrated charge pump that provides full gate drive for battery voltages (Vbb) down to 7 V and reduced gate drive battery voltages as low as 5.5 V, a top-off charge pump (TOCP) that enables 100% pulse-width-modulation (PWM), an adjustable dead-time that can be regulated by the user, an adjustable drain-to-source monitor (VDSTH), and improved fault diagnostics that enhances the user’s ability to decode and identify faults.

The A4933KJPTR-T is available in a 48L eLQFP small profile, thermally-efficient package with exposed pad.

Allegro MicroSystems, Inc. Announces New Automotive Infotainment LED Driver ICs

Wed, 20 Jul 2011 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. announces two new multi-output LED drivers for LCD backlighting. The A8502 and A8514 integrate a current-mode boost converter with internal power switch and multiple current sinks. The LED sinks can be paralleled to-gether to achieve even higher LED currents. They are capable of operating from a single power supply from 5 V to 40 V which allows the part to withstand a load dump condition encountered in automotive systems.

Both the A8502 and A8514 LED drivers can optionally drive an external PMOS to disconnect input supply from the system in the event of a fault. The devices, coupled with the external PMOS disconnect switch, provides protection against output short and overvoltage, open or shorted diode, open or shorted VLED pin, and over-temperature.

A dual level cycle-by-cycle current limit function provides soft start and protects the internal current switch against high current overloads. They have a high PWM switching frequency (>2 MHz) which allows the devices to operate above the AM radio band. They also have a synchronization pin if the user wishes to be synch in the range of 600 kHz to 2.25 MHz.

The A8502KLPTR-T is offered in the 16-pin SSOP package and the A8514KLPTR-T is offered in the 20-pin SSOP package both with exposed thermal pad. Both devices have a 16-week typical lead-time (ARO) to market.

Press Archives

Wed, 13 Jul 2011 10:33:12 -0500

Allegro MicroSystems, Inc. Announces New Unipolar Two-Phase Microstepping Motor Driver

Thu, 07 Jul 2011 00:00:00 -0500

Worcester, MA - Allegro MicroSystems, Inc. announces a new unipolar two-phase constant-current mode motor driver IC which is manufactured and developed by Sanken Electric Co., Ltd. in Japan. The SI-7321M features an efficient unipolar driver design for full- and half-step operation, and 1/4 , 1/8 , and 1/16 microstepping. The clock-in type input interface allows simplified control logic, with the flexibility of sequencer timing using either rising Clock edge only or both rising and falling edges. Additional flexibility is provided by user-configurable blanking time, and load circuit short or open protection (patent pending). Along with inputs for built-in sense current detection, these features minimize power losses. This new motor driver is targeted at the office automation and industrial equipment markets.

The device has a multi-chip internal structure for lower thermal resistance. The control IC (MIC) and the four power elements (MOSFET) are all separate ICs. The package (HSOP) provides wide output terminals at each corner, further enhancing device thermal dissipation.

The built-in excitation distribution circuit (sequencer) allows motor control using only the Clock signal for simple operations (forward, reverse, hold), with motor speed control by frequency input into Clock pin, and rotation direction control by a dedicated logic input. This eliminates logic signal lines required for conventional phase-input methods, and reduces demand on heavily-used CPUs.

Allegro MicroSystems, Inc. Announces a New LED Backlight Driver for Medium/Large Displays

Wed, 01 Jun 2011 12:16:00 -0500

Worcester, MA - Allegro MicroSystems, Inc. announces a new multi-output WLED/RGB driver for backlighting LCD monitors and televisions. The A8516 is a versatile and economical LED driver IC that will enable system designers to reduce component count and overall system cost. The device integrates a boost controller to drive an external MOSFET and six internal current sink channels capable of up to 80 mA each, and channels can be combined together to achieve even higher currents.

The boost converter operates in constant frequency (programmable) current mode control. The LED sink current is set by an external R_ISET resistor and PWM dimming allows LED currents to be controlled. The A8516 provides protection against overvoltage, open or shorted LED string, and over temperature. A dual level cycle-by-cycle current limit function provides soft start and protects against overloads.

The A8516 is offered in a 24-pin TSSOP package (LP), a 24-pin SOICW package (LB), with internally fused pins for enhanced thermal dissipation, both with an exposed thermal pad for enhanced thermal dissipation. Both packages are lead (Pb) free, with 100% matte tin lead frame plating.

Allegro MicroSystems, Inc. Introduces a Fully Integrated DMOS Full-Bridge Motor Driver IC

Tue, 10 May 2011 00:00:00 -0500

Worcester, MA - Allegro MicroSystems, Inc. introduces a new fully integrated single full-bridge DMOS motor driver IC with over-current protection (OCP), internal adjustable pulse-width-modulation (PWM), and a fully integrated charge pump. Allegro’s A4950 is intended for use as a DC brush motor driver with continuous output currents up to 2.5 amperes. Two input terminals are provided for use in controlling the speed and direction of a DC motor with externally applied PWM control signals.

Internal synchronous rectification provides lower power dissipation during PWM operation. Other internal circuit protection includes over-current protection (OCP), motor lead short-to-ground or short-to-supply protection, thermal shutdown with hysteresis, under-voltage monitoring of VBB, and crossover current protection.

The A4950 is targeted at the office automation, industrial and consumer markets. It is provided in an 8L SOICN package with exposed thermal pad (Suffix LJ) for enhanced thermal dissipation.

Allegro MicroSystems, Inc. Announces New Automotive Grade Buck Regulators

Thu, 28 Apr 2011 00:00:00 -0500

Worcester, MA - Allegro MicroSystems, Inc. announces two new robust automotive grade buck regulators with high switching frequency and output current, each integrating a low resistance, high-side, N-channel MOSFET. Allegro’s A8582/A8583 devices incorporate current-mode control to provide excellent loop stability and transient response. These new devices are targeted at the automotive, telecommunications and networking markets.

The A8582/83 devices utilize external compensation to accommodate a wide range of power components and optimize transient response without sacrificing stability. Both devices regulate input voltages from 4.7 V to 36 V down to output voltages as low as 0.8 V, and are able to supply load current of at least 2 A (A8582) or 3.5 A (A8583).

Protection features include VIN under voltage lockout (UVLO), cycle-by-cycle over current protection (OCP), hiccup mode short-circuit protection (HIC), over voltage protection (OVP), and thermal shutdown (TSD). In addition, the A8583 provides unique missing diode (D1) protection, open-circuit, adjacent pin short-circuit, and short-to-ground protection at every pin to satisfy the most demanding applications.

The A8582/A8583 devices are available in a 16-pin TSSOP package with exposed pad for enhanced thermal dissipation and are lead (PB) free with 100% matte tin plated lead frames.

Allegro MicroSystems, Inc. Announces a New Three Phase Brushless DC Motor Pre-Driver IC

Tue, 05 Apr 2011 00:00:00 -0500

Worcester, MA - Allegro MicroSystems, Inc. announces a complete three phase brushless DC motor pre-driver with outputs for direct high current gate drive of an all N-channel power MOSFET three phase bridge with a maximum supply voltage of 38 V. The A4938 includes Hall element inputs, a sequencer for commutation control, fixed off time pulse width modulation (PWM) current control and locked rotor protection. Output current is scalable with the choice of external MOSFETS. ENABLE, DIRECTION and BRAKE inputs can be used to control the motor, speed, position and torque. Output speed can be regulated using open drain FG1 output that changes state at each Hall transition.

This new pre-driver IC is targeted at the office automation, telecommunications, consumer, and industrial markets.

The external MOSFETS can be PWM’d with the ENABLE input or with the internal PWM current regulator. In both cases the A4938 synchronous rectification feature will turn on the appropriate MOSFET(s) during current decay to reduce power dissipation. The A4938 uses low cost Hall elements with noise filtering to prevent false commutation signals. A 5 V regulated supply output is provided to power the three HALL elements. Internal circuit protection includes thermal shutdown with hysteresis, under voltage lockout, over voltage protection with two voltage settings, locked rotor and dead time protection. Special power up sequencing is not required. Operating temperature range is -40°C to 85°C.

The A4938EETTR-T is supplied in a 5 mm × 5 mm 28-lead QFN package with exposed thermal pad. This small footprint package is lead (Pb) free with 100% matte tin leadframe plating.

Allegro MicroSystems, Inc. Introduces Automotive Grade Programmable Bipolar Stepper Motor Driver ICs

Tue, 08 Mar 2011 00:00:00 -0600

Worcester, MA - Allegro MicroSystems, inc. introduces two new flexible microstepping motor drivers each with a built-in translator for easy operation. They both encompass a single-chip solution, designed to operate bipolar stepper motors in full-, half-, quarter- and sixteenth-step modes, at up to 28 V and ±1.4 A. The A3981 and A4980 devices are targeted at the automotive, consumer and industrial markets.

The A3981 can be controlled by simple Step and Direction inputs, or through the SPI-compatible interface that also can be used to program many of the integrated features and to read diagnostic information. The A4980 is identical to the A3981 except for a low-voltage operation feature which will allow the IC to run down to a load supply voltage of 3.3 V (7 V on the A3981.) This low voltage operation can be a necessary feature in some automotive applications where the battery voltage during cold cranking can drop critically low.

The current regulator can be programmed to operate in fixed off-time or fixed frequency PWM, with several decay modes to reduce audible motor noise and increase step accuracy. In addition the phase current tables can be programmed via SPI to create unique microstep current profiles to further improve motor performance for specific applications.

The current in each phase of the motor is controlled through a DMOS full bridge, using synchronous rectification to improve power dissipation. Internal circuits and timers prevent cross-conduction and shoot-through, when switching between high-side and low-side drives. The outputs are protected from short circuits, and features for low load current and stalled rotor detection are included. Chip-level protection includes: hot and cold thermal warnings, overtemperature shutdown, and overvoltage and undervoltage lockout.

The A3981 and A4980 are supplied in a 28-pin TSSOP power package with an exposed thermal pad (package type LP). This package is lead (Pb) free with 100% matte-tin leadframe plating.

Allegro MicroSystems, Inc. Announces A New Dual DMOS Full Bridge Motor Driver IC

Thu, 24 Feb 2011 00:00:00 -0600

Worcester, MA - Allegro MicroSystems, inc. announces a new dual DMOS full bridge motor driver IC targeted at the office automation and consumer and industrial markets. Designed for pulse width modulated (PWM) control of two DC motors, the A4954 is capable of peak output currents to ±2 A and operating voltages to 40 V. Integrated charge pump capacitors reduce external component cost and count.

Input terminals are provided for use in controlling the speed and direction of a DC motor with externally applied PWM control signals. Internal synchronous rectification control circuitry is provided to lower power dissipation during PWM operation. Internal circuit protection includes overcurrent protection, motor lead short to ground or supply, thermal shutdown with hysteresis, undervoltage monitoring of VBB, and crossovercurrent protection.

The A4954ELPTR-T is provided in a low-profile 16-pin TSSOP package with exposed thermal pad (suffix LP) that is lead (Pb) free, with 100% matte tin leadframe plating.

Allegro MicroSystems, Inc. Announces a New Three-Phase Sensorless Fan Driver

Wed, 16 Feb 2011 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. announces a new three-phase, sensorless, brushless DC motor driver IC to complement their existing family of brushless DC devices. Allegro’s new A4934 offers sensorless commutation, a wide supply voltage range, 1.25 A peak output current, -40°C to 105°C operating temperature range, lock detection with auto restart, and a small eTSSOP package with soft switching for reduced audible noise. This new device is targeted at the consumer white goods and office automation markets with key fan applications used in refrigerators and air purifiers.

The motor drive system consists of three half bridge NMOS outputs, BEMF sensing circuits, adaptive commutation control, and state sequencer. The sequencer determines which output devices are active. The BEMF sensing circuits and adaptive commutation circuits determine when the state sequencer advances to the next state.

The three half-bridge outputs are controlled by a state machine with six possible states. Motor BEMF is sensed at the tri-stated output for each state. The BEMF sensing motor commutation relies on the accurate comparison of the voltage on the tri-stated output to the voltage at the center tap of the motor. The BEMF zero crossing, the point where the tri-stated motor winding voltage crosses the center tap voltage, is used as a positional reference. The zero crossing occurs roughly halfway through one commutation cycle.

At startup, commutations are provided by an onboard oscillator in order to step the motor to generate BEMF. When legitimate BEMF zero crossings are detected normal BEMF sensing commutation is achieved.

Adaptive commutation circuitry and programmable timers automatically determine the optimal commutation points with minimal external components. Output speed can be monitored with the FG output signal which occurs when a BEMF zero crossing is detected. Duty cycle control of the PWM input is applied directly to the motor windings to control speed or torque. The PWM input is also used to disable motor operation and put the IC into a low power sleep mode.

Protection features include thermal shutdown with hysteresis, under voltage lockout (UVLO), crossover current and locked rotor protection with auto restart. The A4934GLP-T is supplied in a 16 lead TSSOP package with exposed power tab. The package is lead (Pb) free, with 100%matte tin leadframe plating.

Allegro MicroSystems, Inc. Announces a New Family of User-Programmable, Two-Wire, Unipolar, Hall-Effect Switches

Tue, 08 Feb 2011 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. introduces a new line of user-programmable, two-wire, unipolar, Hall-effect switches to complement its existing family of devices used in seat belt buckle, seat position, and shift selector (PRNDL) applications. These new devices are targeted to serve the automotive market, because they include improved high voltage transient protection; a critical feature for applications that do not allow for protection circuits to be located close to the sensor.

Allegro’s A1190/2/3 family consists of two-wire, unipolar, Hall-effect switches, which can be trimmed by the user at end-of-line to optimize magnetic switchpoint accuracy in the application. These devices are produced on the Allegro® advanced BiCMOS wafer fabrication process, which implements a patented high frequency, 4-phase, chopper-stabilization technique. This technique achieves magnetic stability over the full operating temperature range, and eliminates offsets inherent in devices with a single Hall element that are exposed to harsh application environments.

The A119x family has a number of automotive applications. These include: sensing seat track position, seat belt buckle presence, hood/trunk latching, and shift selector position. Two-wire unipolar switches are particularly advantageous in cost-sensitive applications because they require one less wire for operation versus the more traditional open-collector output switches. Additionally, the system designer inherently gains diagnostics, because there is always output current flowing, which should be in either of two narrow ranges. Any current level not within these ranges indicates a fault condition.

An important upgrade to this family of two-wire switches is the on-chip transient protection and a zener clamp to protect against over-voltage conditions on the supply line. This improved high voltage transient protection allows these devices to survive ISO 7637-2 and 40 V load dump for <0.5 seconds with minimal, and sometime no, protection from discrete components. The ESD protection has been enhanced, such that these devices are capable of handling transients up to 8 kV Human Body Model (HBM).

The A1190, A1192 and A1193 are offered in a SOT-23W style, miniature low profile package (LH) for surface-mount applications.

Allegro MicroSystems, Inc. Introduces a New Family of Two-Wire, Hall-Effect Unipolar Switches

Tue, 18 Jan 2011 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. introduces a new line of two-wire, unipolar, Hall-effect switches to complement its existing family of devices used in seat belt buckle, seat position, and steering lock applications. These new devices are targeted to serve the automotive market, because they include improved high voltage transient protection, which is a feature that is critical for applications, which do not allow protection circuits to be located close to the sensor.

Allegro’s A1152/3/5/6 devices are the next generation of two-wire, unipolar, Hall-effect switches; factory trimmed to optimize the accuracy of the magnetic switch points. These devices employ a patented, high frequency, four-phase, chopper-stabilization technique to achieve magnetic stability over temperature and to eliminate offset inherent in single-element devices, when exposed to harsh automotive environments. Additionally, this advanced chopping technique provides significantly reduced jitter and faster power-on time.

Commonly found in a number of automotive applications, the A1152/3/5/6 devices are utilized to sense: seat track position, seat belt buckle presence, hood/trunk latching, steering lock position, and in shift selectors. Two-wire, unipolar switches require one less wire for operation versus the more traditional open-collector output switches. Additionally, the user gains diagnostics, as there is always current at one of two specified levels. Any output current outside of these two narrow ranges is a fault condition.

An important upgrade to this family is the on-chip transient protection and a Zener clamp to protect against over-voltage conditions on the supply line. This improved high voltage transient protection allows these devices to survive ISO 7637-2 and 40 V load dump for <0.5 seconds with minimal, and sometime no, protection from discrete components. The ESD protection has been enhanced, such that these are capable of handling a transient of 8.0 kV Human Body Model (HBM).

All family members are offered in two package styles: the “LH” is a SOT-23W style, miniature low profile package for surface-mount applications, and, in the coming months, the “UA” is a TO-92 style, three-lead, ultra-mini, Single Inline Package (SIP) for through-hole mounting.

Allegro MicroSystems, Inc. Introduces a New User-Programmable Linear Hall-Effect Sensor IC

Tue, 14 Dec 2010 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. introduces a new user-programmable linear Hall-effect sensor IC with pulse width modulated output. The A1356 complements Allegro’s existing line of linear devices with PWM outputs by offering a device with significantly higher carrier frequency of 2 kHz. This new device targets gear detection, fork, clutch and neutral positions within the automotive market in addition to key applications within the industrial market.

The A1356 device is a high precision, user programmable, Hall-effect linear sensor with a pulse width modulated (PWM), open collector output. The duty cycle (DC) of the PWM output signal (freq: 2 kHz) is proportional to an applied magnetic field. The A1356 device converts an analog signal from its internal Hall sensor element to a digitally encoded PWM output signal. The coupled noise immunity of the digitally encoded PWM output is far superior to the noise immunity of an analog output signal, particularly when the signal needs to travel over long wires within the system.

The BiCMOS, monolithic circuit inside of the A1356 integrates a Hall element, precision temperature-compensating circuitry to reduce the intrinsic sensitivity and offset drift of the Hall element, a small-signal high-gain amplifier, proprietary dynamic offset cancellation circuits, and PWM conversion circuitry. The dynamic offset cancellation circuits reduce the residual offset voltage of the Hall element, which is normally caused by device over molding, temperature dependencies, and thermal stress. The high-frequency offset cancellation (chopping) clock allows for a greater sampling rate, which increases the accuracy of the output signal and results in faster signal processing capability.

The design and manufacturing flexibility of the A1356 is realized through user programmable: gain, quiescent duty cycle, and carrier frequency. The device can be set up in a magnetic circuit and programmed with a train of serial pulses. Once the appropriate parameters have been selected, the codes can be locked for one-time programming. In this manner, manufacturing tolerances can be reduced and the assembly process can be simplified.

The A1356 sensor is provided in a lead (Pb) free, 3-pin, single inline package (KB suffix), with 100% matte tin leadframe plating.

Allegro MicroSystems, Inc. Announces a New Hall-Effect Linear Current Sensor IC

Tue, 30 Nov 2010 00:00:00 -0600

Worcester, MA – Allegro MicroSytems, Inc. introduces a new Hall-effect linear current sensor IC that provides economical and precise solutions for AC or DC current sensing in low-voltage audio, communications systems, white goods, and automotive applications. Typical applications include circuit protection, current monitoring, and motor and inverter control.

Allegro’s device consists of a linear Hall sensor circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which is sensed by the integrated Hall IC and converted into a proportional voltage. Device accuracy is optimized through the close proximity of the magnetic signal to the Hall transducer. The output of the device has a positive slope proportional to the current flow from IP+ to IP– (pins 1 and 2, to pins 3 and 4). The internal resistance of this conductive path is 1.2 mΩ typical, providing a non-intrusive measurement interface that saves power in applications that require energy efficiency.

The ACS711 is optimized for low-side current sensing applications, although the terminals of the conductive path are electrically isolated from the sensor leads (pins 5 through 8), providing sufficient internal creepage and clearance dimensions for a low AC or DC working voltage applications. The thicknessof the copper conductor allows survival of the device at up to 5× overcurrent conditions.

The ACS711 is provided in a small, surface mount SOIC8 package. The leadframe is plated with 100% matte tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. Internally, the device is Pb-free, except for flip-chip high-temperature Pb-based solder balls, currently exempt from RoHS. The device is fully calibrated prior to shipment from the factory.

Allegro MicroSystems, Inc. Announces New High Voltage Three-Phase Motor Driver Family

Tue, 16 Nov 2010 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. announces a new high voltage three-phase motor driver family in a small package that minimizes board space and expands the use of inverter technology (variable speed control) in low power motor drivers. Allegro’s new SX68000M series is targeted at the white good appliance and industrial markets.

Allegro’s SX68000M series of IPM devices has an 85 to 230 VAC input voltage, and a 1.5 to 2.5 A output current. These ICs can withstand voltages of up to 500 V (MOSFET breakdown voltage), providing a robust IPM solution for optimally control-ling motor inverters used to drive small-size motors in residential and commercial appliances. The SX68000M series employs a new, small-footprint proprietary SOP package. The IC itself consists of the necessary power elements (six MOSFETs) and pre-drive ICs (two), needed to configure the main circuit of an inverter. This enables the main circuit of the inverter to be configured with fewer external components.

Allegro MicroSystems, Inc. Introduces a New High Performance Fault Tolerant LED Driver

Tue, 09 Nov 2010 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. introduces a new multi-output white LED driver for LCD backlighting in consumer and industrial displays. Allegro’s new A8515 device has advanced protection features to provide optimized viewing. It integrates a current-mode boost converter with internal power switch and two current sinks.

The boost converter can drive up to 24 LEDs at 120 mA. The two LED current sinks can also be paralleled together to achieve LED currents up to 240 mA. This new device can operate from a single power supply from 5 V to 40 V. The low 720 mV regulation voltage on LED current sources reduces power loss and improves efficiency. A comprehensive fault table is included in the datasheet to describe the leading-edge performance and protection features of the A8515. It also integrates a driver for an (optional) external input disconnect switch.

The A8515GLPTR-T is available in an eTSSOP-16 (LP) exposed pad package for advanced thermal performance.

Allegro MicroSystems, Inc. Announces A New Three-Phase Sensorless Fan Driver

Tue, 26 Oct 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. announces a new three-phase, sensorless, brushless DC motor driver IC to complement their existing family of brushless DC devices. Allegro’s new A4941 offers sensorless commutation, a wide supply voltage range, 1.25 A peak output current, -40°C to 105°C operating temperature range, lock detection with auto restart, and a small eTSSOP package with soft switching for reduced audible noise. This new device is targeted at the consumer white goods and office automation markets with key fan applications used in refrigerators and air purifiers.

The three half-bridge outputs are controlled by a state machine with six possible states. Motor BEMF is sensed at the tri-stated output for each state. BEMF sensing motor commutation relies on the accurate comparison of the voltage on the tri-stated output to the voltage at the center tap of the motor. The BEMF zero crossing, the point where the tri-stated motor winding voltage crosses the center tap voltage, is used as a positional reference. The zero crossing occurs roughly halfway through one commutation cycle.

Protection features include thermal shutdown with hysteresis, under voltage lockout (UVLO), crossover current and locked rotor protection with auto restart. The A4941GLP-T is supplied in a 16 lead TSSOP package with exposed power tab. The package is lead (Pb) free, with 100% matte tin leadframe plating.

Allegro MicroSystems, Inc. Announces Four-Channel Constant Current LED Driver Family

Thu, 14 Oct 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, inc. announces a new family of constant current LED drivers designed to address the emerging requirements of the internal and external illumination applications within the automotive market. Allegro’s A6261/A6262/A6264 four-channel led driver devices have been fully qualified to the highest levels of automotive quality standards and robustness.

The devices each offer four channels of up to 100 mA LED current each, and can be paralleled for higher currents. They operate with a low dropout voltage to minimize power dissipation, and do not require any ballast resistors.

The user selected current is provided to four outputs with each output equally sharing the load. The A6261/62/64 family also features short to ground protection which disables the shorted channel allowing the others to continue to operate. Open LED on any channel is also detected. Similar to the Allegro A6260, the A6261/2/4 family also features a unique current foldback circuit, which uses the chip junction temperature in order to foldback the LED current and to protect the IC and LEDs (if mounted in proximity and on the same substrate).

Key automotive applications include (exterior) brake, turn, tail, and rear combination lighting (RCL) as well as (interior) dome, map, and puddle lighting. There is also a commercial grade version of the 6261 (suffix E) for consumer lighting applications. The A6261/62/64 devices are offered in the eMSOP-10 (LY) and eTSSOP-16 (LP) packages.

Allegro MicroSystems, Inc. Introduces New Dual-Phase DCM Interleaved PFC Controller IC

Mon, 13 Sep 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. announces a new dual-phase DCM interleaved PFC controller IC targeted at the telecom, server, home appliance and industrial markets. Allegro’s SSC2101S is designed specifically for active power factor correction (PFC) converters. When compared to other solutions on the market today Allegro’s new device provides higher efficiency and less EMI noise than comparable devices.

Two boost regulators operating 180° out of phase in Discontinuous Conduction Mode (DCM) enables all switching to be done at zero current. Zero current switching improves efficiency and reduces switching noise and stress on components over a wide range of input voltage and output loadings. The pin count has been minimized (8-pin package) without sacrificing important features such as feedback open loop detection, overvoltage protection, overcurrent protection, and fast load response. Allegro’s SSC2101S enables users to realize high reliability power supply systems with fewer external components.

Allegro MicroSystems, Inc. Introduces New Standard 3 V Smoke Detector

Tue, 13 Jul 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. introduces a new low-current BiCMOS photoelectric smoke detector circuit with ultra-low standby current allowing an average 10-year battery life. Allegro’s A5303 device can be used with an infrared optical chamber to sense light scattered from smoke particles. A networking capability allows units to be interconnected so that if any unit senses smoke all units will sound an alarm. Special features are incorporated in the design to facilitate calibration and testing of the finished detector. This new device is targeted at the consumer smoke alarm market.

A variable-gain photo-amplifier can be directly interfaced to an infrared emitter-detector pair. The amplifier gain levels are determined by two external capacitors and are internally selected depending on the operating mode. Low gain is selected during standby and timer modes. During a local alarm, this low gain is increased (internally) by approximately 45% to provide hysteresis. High gain is used during pushbutton test and to periodically monitor the chamber sensitivity during standby. The internal oscillator and timing circuitry minimize standby power by sensing for smoke for only 100 µs once every 10 s. A special three-stage-speedup sensing scheme is incorporated to minimize the time to an audible alarm and also to reduce false triggering. Chamber sensitivity is periodically monitored and two consecutive cycles of degraded sensitivity are required for a warning signal to occur.

The A5303 is supplied in a thin profile (<1.2 mm overall height) 20-pin TSSOP package (0.65 mm nominal lead pitch). The package is lead (Pb) free with 100% matte tin leadframe plating.

Allegro MicroSystems, Inc. Introduces New Dual Full-Bridge Motor Driver ICs With Overcurrent Protection

Tue, 29 Jun 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. introduces two new motor driver ICs to complement their existing motor driver family. Allegro’s A4986/A4987 devices are dual DMOS full-bridge stepper motor drivers with parallel input communication and overcurrent protection. Each full-bridge output is rated up to 35 V and ±2 A. These devices include a fixed off-time pulse width modulation (PWM) current regulator, along with a 2-bit nonlinear DAC (digital-to-analog converter) that allows stepper motors to be controlled in full, half, and quarter step modes.

The PWM current regulator uses the Allegro® patented mixed decay mode for reduced audible motor noise, increased step accuracy, and reduced power dissipation. Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. Industry standard PHASE, I0, I1 logic inputs are used to control each full-bridge so these motor drivers can easily replace most existing drivers. The outputs are protected from shorts between motor leads and short-to-ground events, which protect the driver and associated circuitry from thermal damage or flare-ups. Other protection features include thermal shutdown with hysteresis, undervoltage lockout (UVLO), crossover current and over-current protection. Special power-up sequencing is not required.

Allegro’s A4986 and A4987 are offered in several different package options: a 24 contact 4.0 mm × 4.0 mm × 0.75 mm QFN (ES) package, and a 24 lead 7.8 mm × 4.4 mm × 1.2 mm eTSSOP (LP) package. Both packages have exposed thermal pads for enhanced thermal dissipation, and are lead (PB) free with 100% matte tin plated lead frames.

Allegro MicroSystems, Inc. Introduces New Three-Phase Brushless DC Motor Pre-Driver IC

Tue, 15 Jun 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. has introduced a new three-phase brushless DC motor pre-driver with outputs for direct high current gate drive of an all N-channel power MOSFET three phase bridge with a maximum supply voltage of 38 V. Allegro’s A4936 device has three Hall-element inputs, a sequencer for commutation control, fixed off-time pulse width modulation (PWM) current control, and locked-rotor detection. The key applications for this new device are laser printer and copier drum drives within the office automation market.

Output current is scaled by the capability of the external MOSFETs. Locked rotor detection delay is set by an external capacitor on the CLD terminal. The PWM, DIR, BRAKE and STOP inputs can be used to control motor speed, position, and torque. Motor speed can be determined using motor FG coil signal that is amplified and shaped with the internal differential amplifier and comparator to produce a digital FGS output. The external MOSFETS can be Pulse-Width-Modulated (PWM’d) using an external signal on the PWM input, or using the internal PWM current regulator. In either case, Allegro’s A4936 synchronous rectification feature reduces power dissipation by turning on the appropriate MOSFETs during current decay.

The Hall elements can be inexpensive types when used with internal noise filtering to prevent false commutation signals. The A4936 provides a regulated 7.5 V supply to power the three Hall elements. Internal circuit protection includes thermal shutdown with hysteresis, under voltage lockout, and dead time protection. Special power-up sequencing is not required. The operating temperature range is -20°C to 105°C.

The A4936 is supplied in a 5 mm × 5 mm, 32-terminal QFN package with exposed thermal pad. This small footprint package is lead (Pb) free with 100% matte tin lead frame plating.

Allegro MicroSystems, Inc. Announces New Ultra-Sensitive Dual-Channel Quadrature Hall-Effect Bipolar Switch

Tue, 01 Jun 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. announces a new dual-channel, bipolar switch with two Hall-effect sensing elements, each providing a separate digital output for speed and direction signal processing capability. The Hall elements are photolithographically aligned to better than 1 µm. Maintaining accurate mechanical location between the two active Hall elements eliminates the major manufacturing hurdle encountered in fine-pitch detection applications. The A1230 is a highly sensitive, temperature stable magnetic sensing device ideal for use in ring magnet based, speed and direction systems located in harsh automotive and industrial environments.

Allegro’s A1230 monolithic integrated circuit (IC) contains two independent Hall-effect bipolar switches located 1 mm apart. The digital outputs are out of phase so that the outputs are in quadrature when interfaced with the proper ring magnet design. This allows easy processing of speed and direction signals. Extremely low-drift amplifiers guarantee symmetry between the switches to maintain signal quadrature. The Allegro® patented, high-frequency chopper-stabilization technique cancels offsets in each channel providing stable operation over the full specified temperature and voltage ranges.

Additionally, the high-frequency chopping circuits allow an increased analog signal-to-noise ratio at the input of the digital comparators internal to the IC. As a result, the A1230 achieves industry-leading digital output jitter performance that is critical in high performance motor commutation applications. An on-chip low dropout (LDO) regulator allows the use of this device over a wide operating voltage range. Post-assembly factory programming at Allegro provides sensitive switchpoints that are symmetrical between the two switches.

The A1230 is available in a plastic 8-pin SOIC surface mount package (L) and a plastic 4-pin SIP (K). Both are available in a temperature range of –40°C to 150°C. Each package is lead (Pb) free, with 100% matte tin plated leadframe.

Allegro MicroSystems, Inc. Announces a New LED Backlight Driver for Medium/Large Displays

Tue, 25 May 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. announces a new multi-output WLED/RGB driver for LED backlighting of LCD Monitors and Televisions. This new device integrates a boost controller that operates in constant frequency (programmable) current mode control, driving an external MOSFET. It integrates six internal current-sinks capable of up to 80 mA each, and they can be combined together to achieve even higher currents. PWM dimming allows LED currents to be precisely controlled as a percentage of the maximum setpoint determined by the user.

Furthermore, multiple A8512s can be connected in parallel, with one master controller controlling the boost stage, and up to five slave controllers, which act as LED sinks. This allows up to 36 LED strings to be powered by just one boost converter significantly reduce the number of external components required.

The A8512 operates from a single supply of 8 to 24 V. It provides protection against overvoltage, open or shorted LED string, and overtemperature. A dual level cycle-by-cycle current limit function provides soft start and protects against overloads.

The A8512 is provided in a 28-contact 5 mm × 5 mm QFN package (ET), with an exposed thermal pad for enhanced thermal dissipation. For single-sided PCB manufacturing capability, the device is also available in a 24-pin SOICW package (LB), with internally fused pins for enhanced thermal dissipation. Both packages are lead (Pb) free, with 100% matte tin leadframe plating.

Allegro MicroSystems, Inc. Announces New DMOS Microstepping Motor Drivers With Overcurrent Protection

Thu, 29 Apr 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. announces the expansion of their microstepping motor driver line to include four new devices that require fewer external components and utilize a simple STEP and Direction interface. Allegro’s A4982/A4984/A4985 and A4988 devices are complete microstepping motor drivers with a built-in translator for easy operation and overcurrent protection to reduce the rework cost in both manufacturing and normal operations. They are targeted at the office automation market.

These latest devices are designed to operate bipolar stepper motors in full-, half-, quarter-, eighth and sixteenth step modes, with an output drive capacity of up to 35 V and ±2 A. They include a fixed off-time current regulator which has the ability to operate in Slow or Mixed decay modes. The translator is the key to the easy implementation of the devices. Simply inputting one pulse on the STEP input drives the motor one microstep. There are no phase sequence tables, high frequency control lines, or complex interfaces to program. The interface is an ideal fit for applications where a complex microprocessor is unavailable or is overburdened.

The chopping control automatically selects the current decay mode (Slow or Mixed). When a signal occurs at the STEP input pin, the device determines if that step results in a higher or lower current in each of the motor phases. If the change is to a higher current, then the decay mode is set to Slow decay. If the change is to a lower current, then the current decay is set to Mixed (set initially to a fast decay for a period amounting to 31.25% of the fixed offtime, then to a slow decay for the remainder of the off-time). This current decay control scheme results in reduced audible motor noise, increased step accuracy, and reduced power dissipation.

Internal synchronous rectification control circuitry is provided to improve power dissipation during PWM operation. Internal circuit protection includes: thermal shutdown with hysteresis, undervoltage lockout (UVLO), crossovercurrent, and over-current protection. Special power-on sequencing is not required.

Allegro’s A4982/A4984/A4985 and A4988 are offered in several different package options: a 28 and 32 contact 5 mm × 5 mm × 0.90 mm QFN (ET) package, a 24 contact 4.0 mm × 4.0 mm × 0.75 mm QFN (ES) package, and a 24 lead 7.8 mm × 4.4 mm × 1.2 mm eTSSOP (LP) package. All packages have exposed thermal pads for enhanced thermal dissipation, and are lead (PB) free with 100% matte tin plated lead frames.

For additional product pictures please click here: A4984, A4985 and A4988

Allegro MicroSystems, Inc. Recognized for Environmental Leadership

Tue, 20 Apr 2010 00:00:00 -0500

Worcester, MA – At a ceremony today, representatives of the Toxics Use Reduction Act (TURA) Program and state legislators presented Allegro MicroSystems, Inc. with an award to acknowledge the company’s environmental leadership.

Allegro MicroSystems, an employer of 500 people in Worcester, Massachusetts, is one of 17 companies across the Commonwealth being recognized by the Toxics Use Reduction Act (TURA) Program as a “TURA 20th Anniversary Leader.” The awards and facility tours are intended to showcase environmental accomplishments—use of safer materials, waste reductions and energy savings—since the Toxics Use Reduction Act was enacted in 1989.

“By continuously working since 1990 to identify and replace toxic chemical use, Allegro has achieved impressive results, both from an environmental and financial perspective,” said Scott Fortier, team leader and trainer at the State’s Office of Technical Assistance (OTA). “On the forefront of environmental innovation for many years, the company has continuously shared its extensive knowledge with other companies through TURA trainings and workshops, which has helped make Massachusetts safer for everyone.”

Allegro’s usage of targeted chemicals has been reduced by 61 percent annually. With its Toxic Use Reduction Program in place, the company has reduced byproduct generated for reported chemicals by 64 percent and has reduced emissions by 88 percent. “These achievements are even more significant when one considers that the very nature of Allegro’s business, a wafer fabrication operation, is very chemical intensive,” said Fortier.

“This is a special recognition for us because our Toxics Use Reduction team works hard to achieve these results,” said Don Alger, Senior Environmental Engineer of Allegro MicroSystems. “Our active Toxics Use Reduction and resource conservation program at our headquarters facility in Worcester has been a contributing factor of our competitiveness in the industry.”

The Toxics Use Reduction Act was expanded in 2006 to include water conservation, energy conservation and waste reduction — and Allegro has achieved significant improvements in these areas as well. As part of its ongoing resource conservation efforts, Allegro has reduced water use by 65 percent, or 94 million gallons a year between 1996 and 2009. During this same period it has reduced oil/natural gas consumption by 14 percent and electricity by 21 percent. Also during this period Allegro has reduced waste generation of items such as chemical containers, cardboard, scrap metal, and regular trash by 398 tons or 82 percent, with the reduction of 25 tons occurring in 2009 alone.

The Toxics Use Reduction Act does not ban chemical use but requires companies to evaluate toxic chemical use, submit usage reports and plans to the state that assess the financial implications of switching to safer alternatives or making changes in production. Since 1989, Massachusetts companies voluntarily reduced toxic chemical use by 41 percent, waste by 71 percent and on-site releases by 91 percent.

For a full schedule of company tours, visit www.turi.org.

For more informtation on Allegro's Environmental Policy, please visit our Quality and Environment section.

Allegro MicroSystems, Inc. Introduces Hall-Effect Latches with Increased Protection for High Voltage Transients

Tue, 20 Apr 2010 00:00:00 -0500

Worcester, MA – Allegro MicroSystems, Inc. adds several new devices to their existing line of Hall-effect latches. The A1225/A1227 and A1229 devices are extremely temperature-stable and stress resistant sensor ICs especially suited for operation over extended temperature ranges to 150°C. The intent of these latches is to provide a more robust product offering for those applications that require high voltage transient protection close to the sensors inside the system. Enhanced ESD structures provide ESD protection up to 8 kV HBM without external protection components and internal protection circuits enable these device to survive 40 V load dump compliance without external protection components. These new devices are targeted at motor commutation applications in sunroofs and power windows within the automotive market.

Superior high temperature performance is made possible through a novel Schmitt trigger circuit that maintains operate and release point symmetry by compensating for temperature changes in the Hall element. Additionally, internal compensation provides magnetic switchpoints that become more sensitive with temperature, hence offsetting the usual degradation of the magnetic field with temperature. The symmetry capability makes these devices ideal for use in pulse-counting applications where duty cycle is an important parameter.

The three basic devices (A1225, A1227, and A1229) are identical except for magnetic switchpoints. Each device includes on a single silicon chip a voltage regulator, Hall-voltage generator, temperature compensation circuit, signal amplifier, Schmitt trigger, and a buffered open-drain output to sink up to 25 mA. The on-board regulator permits operation with supply voltages of 3.8 to 24 V.

The first character of the part number suffix determines the device operating temperature range. Suffix L is for –40°C to 150°C. Two package styles provide a magnetically optimized package for most applications. Suffix LT is a miniature SOT89/ TO-243AA transistor package for surface-mount applications, suffix UA is a three-lead ultra-mini-SIP. Both packages are lead (Pb) free with 100% matte tin leadframe plating.

Allegro MicroSystems, Inc. Announces New Ultra Small Xenon Photoflash Drivers

Tue, 30 Mar 2010 00:00:00 -0500

Worcester, MA - Allegro MicroSystems, Inc. announces two new Xenon photoflash charger ICs with robust features in an extremely small footprint. The new A8732 and A8735 represent the latest generation of drivers that are designed to meet the needs of ultra low power, small form factor cameras, including camera phones.

Size and cost are minimized through the high level of integration and minimal components required, while using a tiny 2 × 2 mm DFN package. Battery life is extended by utilizing primary-side voltage sensing to remove the need for a secondary-side voltage divider and associated leakage current. Furthermore, these devices feature very low supply current in both shutdown and standby mode.

The switch current limit in the A8732 can be programmed from 0.45 to 1.5 in 16 steps with single wire interface, while the current limit for the A8735 is fixed at the popular setting of 1 A. The IGBT driver also has internal gate resistors for minimum external component count. The charge and trigger voltage logic thresholds are set at 1 V_HI(min) to support applications implementing low-voltage control logic such as mobile phones.

The devices are available in an 8-contact 2 mm × 2 mm DFN package with a 0.60 maximum overall package height.

Allegro MicroSystems Announces New High Power LED Driver For Medium LCD Display Backlighting

Tue, 26 Jan 2010 00:00:00 -0600

Worcester, MA – Allegro MicroSystems, Inc. introduces a new high power LED driver with output disconnect for backlighting medium LCD displays. This new driver is a robust solution targeting numerous applications within the automotive market. Typical applications include in-dash navigation systems, automotive infotainment, and back-up camera displays. A commercial version is also available for industrial and consumer applications.

Allegro’s A8501 integrates a boost converter and four 100 mA current sinks. LED channels can be tied together for up to 400 mA sink capability. It can work from a single power supply of 8 to 21 V and withstand up to 40 V. The boost converter is a constant frequency, current-mode converter.

Operating frequency can be set up to 2 MHz in order to avoid interference with the AM radio band in automotive applications. The integrated boost DMOS switch is rated for 40 V at 3.6 A. PWM dimming allows LED currents to be controlled at up to a 1000:1 ratio. Additional 4:1 dimming can be achieved by using the DIM pin. As part of an extensive list of protection features, the A8501 provides protection against output connector shorts through an integrated output disconnect switch. It also includes adjustable overvoltage protection (OVP) and protects against open or shorted LEDs and an open OVP resistor or boost diode.

The device is supplied in a surface mount, 28-pin TSSOP package (suffix LP), with exposed thermal pad for enhanced thermal dissipation. It is available with an ambient operating temperature of either 125°C or 85°C maximum, for automotive or industrial/consumer applications. The device is lead (Pb) free, with a leadframe plating choice of 100% matte-tin (suffix T) or tin-bismuth (suffix B).