Ultra Low Iq, Wide Input, 2.4MHz, 1 Amp Synchronous Buck Regulator


Allegro 20-Pin 4mmx4mm QFN ES with wettable flank package


Top Features


The ARG81800 includes all the control and protection circuitry to produce a PWM regulator with ±1.5% output voltage accuracy, with ultralow quiescent current to enable “keepalive” supply operation with minimal current draw from the supply during very light load regulation. There are two versions of the ARG81800 available, 500 mA and 1 A, so the physical size of the power components can be optimized for lower current systems, thus reducing PCB area and saving cost. PWM switching frequency can be programmed over a wide range to balance efficiency, component sizing, and EMC performance. If VIN decays and the duty cycle reaches its maximum, the ARG81800 will automatically fold back its PWM frequency to extend the duty cycle and maintain VOUT.

The ARG81800 employs Low-Power (LP) mode to maintain the output voltage at no load or very light load conditions while drawing only micro-amps from VIN. The ARG81800 includes a PWM/AUTO control pin so the system can dynamically force either PWM or AUTO mode by setting this pin high or low, respectively.

If the SYNCIN pin is driven by an external clock, the ARG81800 will be forced into PWM mode and synchronize to the incoming clock. The ARG81800 adds frequency dithering to the SYNCIN clock to reduce EMI/EMC. The ARG81800 provides a CLKOUT pin so “downstream” regulators can be easily interleaved and dithered via their synchronization inputs.

The ARG81800 has external compensation, so it can be tuned to satisfy a wide range of system goals with many different external components over a wide range of PWM frequencies. The ARG81800 includes adjustable soft start to minimize inrush current. The ARG81800 monitors the feedback voltage to provide an open-drain power good signal. The Enable input can command an ultra-low current shutdown mode with VOUT = 0 V.

Extensive protection features of the ARG81800 include pulse-by-pulse current limit, hiccup mode short circuit protection, BOOT open/short voltage protection, VIN undervoltage lockout, VOUT overvoltage protection, and thermal shutdown. The ARG81800 is supplied in a low profile 20-pin wettable flank QFN package (suffix “ES”) with exposed power pad.

  • Automotive AEC-Q100 qualified
  • Input operating voltage range: 3.5 to 36 V
    • Withstands surge voltages to 40 V for load dump
  • Low-Power (LP) mode—draws just 8 μA from VIN while maintaining 3.3 or 5.0 VOUT
  • AUTO mode allows automatic transition between PWM and LP mode based on load current
  • Programmable PWM frequency (fSW): 250 kHz to 2.4 MHz
  • PWM frequency dithering and controlled switch node slew rate reduce EMI/EMC signature
  • CLKOUT allows interleaving and dithering of “downstream" regulators using their synchronization inputs
  • Interleaving minimizes input filter capacitor requirement and improves EMI/EMC performance
  • Synchronization of PWM frequency to external clock on SYNCIN pin
  • Adjustable output voltage: ±1.5% accuracy over operating temperature range (‒40°C to 150°C)
  • Maximized duty cycle at low VIN improves dropout
  • Soft recovery from dropout condition
  • Adjustable soft-start time controls inrush current to accommodate a wide range of output capacitances
  • External compensation provides flexibility to tune the system for maximum stability or fast transient response
  • Enable input can command ultralow 1 μA shutdown current
  • Open-drain PGOOD output with rising delay
  • Pre-bias startup allows quick restart and avoids reset
  • Overvoltage, pulse-by-pulse current limit, hiccup mode short circuit, and thermal protections
  • Robust FMEA: pin open/short and component faults

The ARG81800 is supplied in a low profile 20-pin wettable flank QFN package (suffix “ES”) with exposed power pad.

ES Package Documentation

Part Number Specifications and Availability

Documentation and Resources


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