Called A4964, it works with external n-channel mosfets and is designed to work in systems where a small microcontroller provides communication to a central electronic control unit (ECU), plus intelligent fault and status handling.
It provides the power supply and watchdog for the microcontroller, as well as the high-voltage interfaces between the microcontroller and the central ECU and ignition switch. It can also operate as an independent single chip remote motor controller (see diagrams).
Motor drive is through three-phase sinusoidal current, where phase commutation is determined, without the need for independent position sensors, by monitoring motor back-EMF.
“The sensor-less start-up scheme includes forward and reverse pre-rotation [windmill] detection and synchronisation, and allows the device to operate over a wide range of motor and load combinations,” said Allegro.
There are three control modes:
Control mode, operating mode, and bridge parameters are programmed through an SPI-compatible serial interface.
A single current sense amplifier provides peak current limiting and average current measurement through the serial interface.
Integrated diagnostics indicate: under-voltage, over-temperature, and power bridge faults, and can protect the power switches under “most” short-circuit conditions, said the firm.
It is available in 36pin QFN and 32-lead QFP – both with exposed thermal pad for heat sinking.