Full bridge gate drivers have direct control and PWM options
Full bridge gate drivers are available from Allegro MicroSystems with direct control or pulse width modulation (PWM) options.
The A89505 (direct control) and the A89506 (PWM) are 4.0 x 4.0mm 50V full bridge drivers for automotive and industrial applications. The drivers integrate critical features to make system design easier, replacing mechanical relays with solid state drivers to improve performance and reliability. Built-in capabilities include flexible interface logic, EMI mitigation with programmable gate drive, motor current feedback and multiple diagnostic features. They are supplied in a 4.0 x 4.0mm QFN package which is 36 per cent smaller than comparable 5.0 x 5.0mm devices.
The A89505 and A89506 are suitable for vehicle applications such as window and door actuators, EV charger locks, electronic parking brakes and folding mirrors. The solid state design also makes them suitable for battery-powered applications that incorporate brushed DC motors such as building automation and robotics. Allegro said in these application they are able to improve 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, Allegro claimed. Integrated diagnostics remove the need for additional microprocessor programming and addition circuitry.
The A89505 and A89506 are both capable of 50V absolute maximum supply voltages and offer high gate drive voltage at low VBB and are efficient when running on battery power, allowing designers to specify lower-cost FETs, said the company. They also enable lower current draw in standby states to reduce total battery load.
Steve Lutz, business line director for motor drivers at Allegro, said there were other benefits besides being smaller that alternative drivers to shrink overall PCB sizes and accommodate more compact modules in space-conscious designs. “Both drivers are easier to use and implement than relays or discrete systems, and increase overall reliability while reducing power consumption,” he said.
The A89505 and A89506 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 ECU to detect pinches or stalls, with the ability to overdrive a motor in case of ice or freezing.
The two drivers are available in a low profile 4.0 x 4.0mm, 20-contact QFN package (suffix “ES”) and a 20-lead eTSSOP (suffix “LP”), both with exposed thermal pad.
