A4957: Full Bridge MOSFET Driver


The A4957 is a full-bridge controller for use with external N-channel power MOSFETs and is specifically designed for applications with high-power inductive loads such as brush DC motors.

A unique charge pump regulator provides full ( >10 V ) gate drive for battery voltages down to 7 V and allows the A4957 to operate with a reduced gate drive, down to 4.5 V.

A bootstrap capacitor is used to provide the above battery supply voltage required for N-channel MOSFETs. A unique bootstrap charge management system ensures that the bootstrap capacitor is always sufficiently charged to supply the high-side gate drive circuit.

Each of the power MOSFETs is controlled independently but all are protected from shoot-through by dead time that is userconfigured by an external resistor.

Integrated diagnostics provide indication of undervoltage and overtemperature faults.

The A4957 is supplied in a 24-contact 4 mm × 4 mm × 0.75 mm QFN with an exposed pad for enhanced thermal dissipation. It is lead (Pb) free, with 100% matte tin leadframe plating (suffix –T).

Top Features

  • High current gate drive for N-channel MOSFET full bridge
  • Independent control of each MOSFET
  • Charge pump for low supply voltage operation
  • Cross-conduction protection with adjustable dead time
  • 4.5 to 50 V supply voltage range
  • Diagnostics output
  • Low current sleep mode

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check Stock
A4957SESTR-T 24-lead QFN -20°C to 85°C Yes View Data Contact your
local sales rep
Distributor Stock
APEK4957SES-01-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Distributor Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.