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).
