Automotive 3-phase sensorless brushless DC motor controller IC

December 07, 2011 // By Julien Happich
The A4960 from Allegro MicroSystems Europe is a 3-phase sensorless brushless DC motor controller IC that incorporates extensive diagnostic and protection features. Designed for use with external N-channel power MOSFETs, the new device is suited to the control of pumps, blowers and cooling fans in automotive applications.

The motor drive system uses a block commutation (trapezoidal drive) approach, 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. External bootstrap capacitors are used to provide the voltage (above the battery supply voltage) required to drive the 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 A4960 operates over a supply voltage operating range from 7 to 50V, and is compatible with 3.3 and 5V logic. 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 FETs under most short-circuit conditions. Detailed diagnostics are available as a serial data word output or through a programmable diagnostic output. The A4960 is supplied in a 32-lead eLQFP package. This package is available in lead (Pb) free versions, with 100% matt tin lead-frame plating.

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