Sensorless BLDC Motor Driver

The A4960 is a three-phase, sensorless, brushless DC (BLDC) motor controller for use with external N-channel power MOSFETs. Allegro offers three versions of the A4960. The A4960KJPTR-T and the A4960KJPTR-A-T are automotive grade ICs that have been fully qualified to AEC-Q100 standards. The original A4960KJPTR-T design was enhanced to improve EMC performance. This device, A4960KJPTR-A-T, is a drop-in replacement. While Allegro continues to support existing designs using the A4960KJPTR-T, it will transition all new designs and customers to the “-A” version. Allegro supports designs that are in progress or designs for those who cannot switch to the “-A” version. In addition to this enhanced automotive version, Allegro offers a commercial grade, “S” temperature range version of the A4960, A4960SJPTR-T.

The A4960 drives a motor using block commutation (trapezoidal drive) where phase commutation is determined, without the need for independent position sensors, by monitoring the motor back-EMF. A programmable motor start-up scheme allows the A4960 to be adjusted for a wide range of motor and load combinations.

An external bootstrap capacitor is used to provide the above battery supply voltage required for N-channel MOSFETs. An automatic internal bootstrap charge management scheme ensures that the bootstrap capacitor is always sufficiently charged for safe operation of the power MOSFETs. The power MOSFETs are protected from shoot-through by integrated crossover control and adjustable dead time.

Integrated diagnostics provide indication of undervoltage, overtemperature, and power bridge faults and can be configured to protect the power MOSFETs under most short circuit conditions. Detailed diagnostics are available as a serial data word.