Automotive H-bridge motor driver makes 12V brushed motor control easy

When the power stage and protection are in one chip it saves board space, design work and fault management. The VNH9045AQ has two high-side drivers and two low-side switches in an integrated H-bridge. This is for motor control on 12V systems.

The VNH9045AQ works well in cars and other vehicles. The motor driver is good to go because it meets the AEC-Q100 standard and it is also ready for ISO 26262. The motor driver works with 3V complementary metal-oxide-semiconductor (CMOS) logic inputs. The motor driver operates from 4V to 28V, and can handle a transient supply voltage of 36V. Speed control is supported with pulse-width modulation up to 25kHz. When the motor driver is not being used the standby current is a really low at 1µA, at 25°C.

The VNH9045AQ offers protection which includes under-voltage shutdown, over-voltage clamp, thermal shutdown and cross-conduction protection. It also limits current and power and protects against loss of ground and loss of supply voltage. The outputs are protected against short-to-ground and short-to-supply voltage events. The side current limit is 23A to 46A and low-side shutdown current is 28A to 56A.

The chip also has built-in monitoring and diagnostics. The multisense pin gives analog motor feedback, chip temperature warning and fault reporting. A dedicated feedback pin reports the actual voltage state of one motor output terminal back to the microcontroller, allowing the system to verify correct H-bridge switching for safety monitoring. In the off state these pins also support load and short to supply voltage checks before the motor starts.

The quad flat no-lead (QFN) 6mm x 6mm triple pad 26+2L package helps with layout performance. The package uses three exposed islands for heat dissipation. ST also provides a six-layer printed circuit board (PCB) reference layout and thermal data.