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  • DC Motor Driver with SPI Monitoring and Control Features

  • Created: Jan 10, 2016

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The MC33899VWR2 device is a DC motor driver that is based on an H-bridge configuration, which enables the motor to rotate in forward or reverse direction. It offers analog control and protection by integrating an internal voltage regulator, current sensor, and temperature sensor. The device has an SPI port, which allows control of slew rate and current compensation limits with the help of a microcontroller. Its SPI port also includes reading of diagnostic status or faults such as open circuit, short-circuit to VIGNP, short-circuit to ground, die temperature range, or under-voltage on VIGNP.

This reference design shows a typical application diagram for the MC33899VWR2 device. Its internal analog circuitry is powered by a 5V power supply through terminal block ST3, while the H-bridge is powered by another power source (0-26.5V) through terminal block ST2. The power input for the H-bridge is not protected against reverse voltage, so an external diode D1 is placed inverted at the H-bridge power input side. The H-bridge output S0 and S1 for the DC motor is connected to terminal block ST1. The male pin header J1 is connected to the SPI port, while J2 is connected to the direction and speed control of the motor driver defice. A capacitor (C1) is placed at VCCL pin to insure proper startup sequencing. The resistor RCSNS sets the current to voltage gain from the load current feedback coming from the CSNS pin, while capacitor C2 provides the filtering. The voltage drop across the RCSNS represents the amount of current drawn by the load or the DC motor. The capacitor CRES acts as an external reservoir, while capacitor CREDIS determines the time interval for the low side MOSFET to automatically re-enable. The resistor RS determines the slew rate of the high side and low side MOSFETS.

The direction of the DC motor rotation is dependent on the FWD and REV inputs. These pins can be controlled by a microcontroller. The speed and torque of the motor will depend on the duty cycle of the PWM signal provided by the microcontroller to the MC33899VWR2 device. The enable inputs (EN1, EN2) must be also set to HIGH so that the output drivers are enabled. When connecting the device SPI port to the microcontroller, make sure that the logic out bias (VDDQ) is connected to the same power supply used by the microcontroller.