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Related Links:

Datasheets:
A6278 and A6279: Serial-Input, Constant-Current Latched LED Drivers with Open LED Detection (PDF)

Selection Guides:
Power Integrated Circuits,

LED Display Drivers,

Relay/Solenoid Drivers

when this product is updated

Technical Publications:
Constant-Current LED Drivers (PDF),

A6279 Timing Requirement (PDF)

Press Releases:
A6278: Allegro Announces a New Eight Channel Constant-Current Latched LED Driver with Open LED Detection,

A6279: Allegro Announces a New 16-Bit Serial-Input, Constant-Current Latched LED Driver with Open LED Detection

A6278 and A6279
Serial-Input, Constant-Current Latched LED Drivers with Open LED Detection

Features

• 3.0 to 5.5 V logic supply range
• Schmitt trigger inputs for improved noise immunity
• Power-On Reset (POR)
• Up to 90 mA constant-current sinking outputs
• LED open circuit detection
• Low-power CMOS logic and latches
• High data input rate
• 20 ns typical staggering delay on the outputs
• Internal UVLO and thermal shut down (TSD) circuitry

Description

The A6278 and A6279 devices are specifically designed for LED display applications. Each of these BiCMOS devices includes a CMOS shift register, accompanying data latches, and NPN constant-current sink drivers. The A6278 contains 8 sink drivers, while there are 16 in the A6279.

The CMOS shift register and latches allow direct interfacing with microprocessor-based systems. With a 3.3 or 5 V logic supply, typical serial data-input rates can reach up to 25 MHz. The LED drive current is determined by the user’s selection of a single resistor. A CMOS serial data output permits cascading between multiple devices in applications requiring additional drive lines. Open LED connections can be detected and signaled back to the host microprocessor through the SERIAL DATA OUT pin.

Four package styles are provided: an MLP/QFN surface mount, 0.90 mm overall height nominal (A6279 only); a DIP (type A) for through-hole applications; and for leaded surface-mount, an SOIC (type LW) and a TSSOP with exposed thermal pad (type LP). All package styles for the A6278 are electrically identical to each other, as are the A6279 package styles. All packages are lead (Pb) free, with 100% matte tin plated leadframes.

Functional Block Diagram

Complete Part Numbers

Part Number	Package Type	RoHS Compliant	Part Composition/ RoHS Data	Temperature	Comments	Samples	Distributor Stock
A6278EA-T	16-pin DIP	Yes	view data	-40 °C to  85 °C
A6278ELP-T	16-lead TSSOP	Yes	view data	-40 °C to  85 °C
A6278ELPTR-T	16-lead TSSOP	Yes	view data	-40 °C to  85 °C		samples not available
A6278ELW-T	16-lead SOIC	Yes	view data	-40 °C to  85 °C
A6278ELWTR-T	16-lead SOIC	Yes	view data	-40 °C to  85 °C		samples not available
A6279EA-T	24-pin DIP	Yes	view data	-40 °C to  85 °C
A6279EET-T	28-lead QFN	Yes	view data	-40 °C to  85 °C
A6279ELP-T	24-lead TSSOP	Yes	view data	-40 °C to  85 °C
A6279ELPTR-T	24-lead TSSOP	Yes	view data	-40 °C to  85 °C		samples not available
A6279ELW-T	24-lead SOIC	Yes	view data	-40 °C to  85 °C
A6279ELWTR-T	24-lead SOIC	Yes	view data	-40 °C to  85 °C		samples not available

Allegro's products are not to be used in life support devices or systems, if a failure of an Allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system.