Full-bridge gate drivers for automotive and industrial applications

Allegro MicroSystems, Inc. provides two new full-bridge gate drivers for automotive and industrial applications. Offered with direct control (A89505) and pulse-width modulation (A89506) options, these devices up-integrate crucial elements to make system design simpler, replacing mechanical relays with solid-state drivers to enhance performance and reliability. With built-in capabilities incorporating flexible interface logic, EMI mitigation with programmable gate drive, motor current feedback and multiple diagnostic features, these devices need very few external components and are provided in a 4mm x 4mm QFN package, 36% smaller than comparable 5mm x 5mm devices.

The A89505 and A89506 are excellent for vehicle applications including window and door actuators, EV charger locks, electronic parking brakes, and folding mirrors. Their solid-state design also makes them excellent for battery-powered applications that include brushed DC motors such as building automation and robotics, enhancing reliability and battery life while enabling smaller design footprints.

Both drivers contain built-in current sensing capabilities, eradicating the necessity for external current sense resistors and declining external component requirements to as few as seven. Integrated diagnostics further prevent the necessity for additional microprocessor programming and additional circuitry. Designers can fit the functionality they need into smaller system footprints, reducing BOM and PCB sizes while increasing performance and enhancing the consumer experience.

Both devices are capable of 50V absolute maximum supply voltages and provide higher gate drive voltage at low VBB and better efficiency when running on battery power, enabling designers to specify lower-cost FETs. They even help lower current draw in standby states to reduce total battery load.

“As cars continue down a path toward full electrification, designers are looking for motor drivers that increase performance and battery life without adding size to system designs. The same goes for people designing for Internet of Things and industrial applications,” says Steve Lutz, business line director for Motor Drivers at Allegro. “In addition to being 36% smaller than other drivers on the market, the A89505 and A89506 include advanced features and capabilities that help designers shrink overall PCB sizes and fit everything into more compact modules. Both drivers are easier to use and implement than relays or discrete systems, and increase overall reliability while reducing power consumption.”

The gate drivers assist to provide better motor control than mechanical relays and lessen the requirement for external components. Programmable gate drive decreases EMI and transients induced by fast switching, and the drivers can adjust gate current to better control the slew rate of external MOSFETs.

Both devices possess current limit detection flags, which are triggered when the programmable current limit is reached. This feature allows a vehicle ECU to detect pinches or stalls, with the ability to overdrive a motor in case of ice or freezing.