MC33926 Motor Driver Carrier

MC33926 Motor Driver Carrier - The MC33926 motor driver carrier will offer up to nearly 3 a continuous current to one brushed DC motor at 5 V to 28 V, and it will tolerate peak currents up to 5 A for some seconds, making this a good all-purpose motor driver for medium-sized DC motors. The MC33926 supports ultrasonic (up to twenty kHz) pulse width modulation (PWM) of the motor output voltage, that eliminates the audible switching sounds caused by the speed controller of the PWM, and the feedback circuit outputs an analog voltage on the FB pin that's proportional to the output current.

Basic Application Connections

Each motor driver channel is connected to a microcontroller via five I/O lines in a typical application: the two input lines, IN1 and IN2, for direction control; one of the disable lines, D1 or D2, for PWM speed control; the current sense output, FB, for monitoring motor current draw (connected to an analog-to-digital converter input); and the status flag, SF, for monitoring motor driver errors.

If PWM signals are applied directly to the two input pins while keeping both the disable pins idle, the number of control lines per channel can be decreased to two pins. To ensure correct functionality in any of these scenarios, the other unused lines must be set. Without adding additional wires to the module, it is simple to override the motor driver defaults using the jumper points on the circuit board.

Although monitoring the status flags can help identify latching fault conditions, the connections for the current sense and status flags are optional. Since the status flags are open-drain outputs, they can be connected in situations where there aren't many I/O pins and it's not important to identify which motor driver is having a problem.

Keep in mind that both motor driver chips are kept in a low-current sleep mode when the enable pin, EN, is in its default condition of LOW. To enable the board to function, you must maintain this pin high (either via an external connection or the default-overriding jumper next to the pin).

Protection

The MC33926 is protected from under voltage, overcurrent, and over temperature. The status flag pins indicate some protection-related occurrences (SF). Which can be attached to a single input and are active-low pins. The chip latches LOW and sets OUT1 and OUT2 to high impedance if it senses an over-current or over-temperature incident. Toggle the D1, D2, EN, or VIN lines to release the status flag pin's latch. The motor driver chips are further protected on the carrier board by a reverse-protection MOSFET.