The A3932 is a three-phase MOSFET controller for use with bipolar brushless DC motors. Its high gate-current drive capability allows driving a wide range of N-channel power MOSFETs and can support motor supply voltages to 50 V. Bootstrapped high-side drive blocks provide the floating positive supplies for the gate drive and minimize the component count normally required. The high-side circuitry also employs a unique FET monitoring circuit that ensures the gate voltages are at the proper levels before turn-on and during the ON cycle.
Internal fixed off-time PWM current-control circuitry can be used to regulate the maximum load current to a desired value. The peak load-current limit is set by the user’s selection of an input reference voltage and external sensing resistor. The fixed off-time pulse duration is set by a user-selected external RC timing network. For added flexibility, the PWM input can be used to provide speed/torque control, allowing the internal current control circuit to set the maximum current limit.
Optional synchronous rectification is included. This feature will short out the current path through the power MOSFET reverse body diodes during the PWM off-cycle current decay. This can minimize power dissipation in the power MOSFET, eliminate the need for external power clamp diodes, and potentially allow more economical choices for the MOSFET application.
The A3932 includes the commutation logic for Hall sensor ICs configured for 120 degree spacing. Power MOSFET protection features include bootstrap capacitor charging current monitor, undervoltage monitor, motor-lead short-to-ground, and thermal shutdown.