Automotive DC Motor Drive Summary: More and more motors are being used in automobiles, and choosing a brushed DC motor drive that meets automotive-grade requirements simplifies design and improves safety performance. This article introduces the HCV7535, a function-enhanced H-bridge pre-driver chip that meets automotive-grade requirements.

1. Application of brushed DC motors in automobiles

The application of electric motors in automobiles enables automobiles to realize automation and enhance driving safety and comfort. Different types of motors are applied to different functional modules in automobiles due to their own characteristics. Brushed DC motors are also used in multiple functional modules of automobiles, as shown in the figure below.

Brushed DC Motor Applications

The automatic window lifter is basically available in every car now, so there is no need to use the traditional hand-crank type; the electric seat adjustment also replaces the traditional manual mechanical type; the electric trunk and electric sunroof are even more important for luxury cars. configuration, these are achieved by brushed DC motors.

2. Driven by brushed DC motor

To drive a brushed DC motor, high-side drive or low-side drive can be used, and the control power supply can be connected to the input end of the motor, which is simple and practical. When it is necessary to control the motor to realize forward and reverse rotation, an H bridge can be built to realize it, as shown in the following figure.

Motor H-bridge driver

A simple H-bridge circuit can be implemented using two relays, and the external circuit can drive the relay to be closed. Although such a relay H-bridge drive is simple and practical, it also has relatively large limitations, such as large size and slow switching speed, and it is also powerless in speed regulation. Under the current trend of high power density requirements, higher switching speeds and smaller devices are required to replace relays. The MOS tube has fast switching speed, small on-resistance, strong overcurrent capability, and non-contact electronic switch. It is very suitable for replacing relays to drive brushed DC motors, and it is easier to reduce the circuit footprint. Since the switching speed of the MOS tube is very high compared to the relay, the speed can be adjusted by PWM.

The requirements of automotive electronic design are getting higher and higher, and functional safety and fault checking mechanisms are an indispensable part. When designing a driver for a DC brush motor that meets the automotive standard, it is of course preferred to choose a driver chip that meets the automotive standard.

3. H-bridge pre-drive NCV7535

The NCV7535 launched by ON Semiconductor is a function-enhanced H-bridge driver chip, which can be configured through the SPI interface. It can provide an N-MOS anti-reverse circuit design charge pump and support a variety of protection mechanisms. It is a highly integrated device. Automotive grade chip, the chip frame is shown in the figure below.

NCV7535 frame

Main features of NCV7535:

Wide input voltage range;

Provide charge pump for N-MOSFET anti-reverse connection protection circuit;

The microcontroller can be configured through the SPI interface;

Control the H bridge to realize the forward and reverse rotation of the motor;

PWM input to adjust torque and speed;

Enhanced H-bridge pre-drive, stable and reliable;

Support active freewheeling and passive freewheeling;

Programmable slew rate and dead time;

Integrated overvoltage, short circuit, over temperature detection and protection.

NCV7535 Application

NCV7535 is designed with automotive electronic standards, highly integrated with multiple functions, very suitable for car window control, door control, etc. (as shown in the example above). The stable and reliable circuit solution is the preferred choice for brushed DC motor drive.