Allegro MicroSystems announced two new full-bridge gate drivers for automotive and industrial applications. Available with direct control (A89505) and pulse-width modulation (A89506) options, these devices up-integrate critical features to make system design easier, replacing mechanical relays with solid-state drivers to improve performance and reliability. With built-in capabilities including flexible interface logic, EMI mitigation with programmable gate drive, motor current feedback and multiple diagnostic features, these devices require very few external components and are available in a 4×4 mm QFN package, 36% smaller than comparable 5×5 mm devices.
According to the vendor, the A89505 and A89506 are ideal for vehicle applications such as window and door actuators, EV charger locks, electronic parking brakes, and folding mirrors. Their solid-state design also makes them suitable for battery-powered applications that incorporate brushed DC motors, improving reliability and battery life while facilitating smaller design footprints.
Both drivers include built-in current sensing capabilities, eliminating the need for external current sense resistors and reducing external component requirements to as few as seven. Integrated diagnostics further obviate the need for additional microprocessor programming and addition circuitry. Designers can fit the functionality they need into smaller system footprints, reducing bills of materials (BOMs) and printed circuit board (PCB) sizes while increasing performance and improving the consumer experience.
Both new chips are capable of 50V absolute maximum supply voltages and offer higher gate drive voltage at low VBB and better efficiency when running on battery power, allowing designers to specify lower-cost FETs. They even enable lower current draw in standby states to reduce total battery load.
The new gate drivers help provide better motor control than mechanical relays and reduce the need for external components. Programmable gate drive reduces EMI and transients caused by fast switching, and both drivers can adjust gate current to better control the slew rate of external MOSFETs.
Both devices include current limit detection flags, which are triggered when the programmable current limit is reached. This feature allows a vehicle electronic control unit (ECU) to detect pinches or stalls, with the ability to overdrive a motor in case of ice or freezing.