Automotive Three-Phase MOSFET Driver

The A4918 is an N-channel power MOSFET driver capable of controlling MOSFETs connected in a 3-phase bridge arrangement and is specifically designed for automotive applications with high-power inductive loads, such as BLDC motors. A unique charge pump regulator provides the supply for the MOSFET gate drive for battery voltages down to 7 V and allows the A4918 to operate with a reduced gate drive down to 4.5 V. Gate drive voltage and strength are programmable to help reduce EMC issues. A bootstrap capacitor is used to provide the above-battery supply voltage required for N-channel MOSFETs with an additional above-battery charge pump to ensure that the bootstrap capacitors remain charged when held in the on state. Full control is provided over all six power MOSFETs in the 3-phase bridge, allowing motors to be driven with block commutation or sinusoidal excitation.

The power MOSFETs are protected from shoot-through by integrated crossover control and optional programmable dead time. Integrated diagnostics provide indication of multiple internal faults, system faults, and power bridge faults, and can be configured to protect the power MOSFETs under most short circuit conditions. For safety-critical systems, the integrated diagnostic operation can be verified under control of the serial interface. The serial interface is provided to alter programmable settings and read back detailed diagnostic information.

Allegro recommended automotive-qualified Hall latches: APS122x5 and APS122x0. 

The A4918 is supplied in a 48-lead QFP package with exposed thermal pad as well as a in a new 7x7 48L QFN package with exposed thermal pad (reducing the PCB footprint by ~40%). These packages are lead (Pb) free with 100% matte tin leadframe plating.