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I am using the MC33887 driver to control a 24V brushed DC motor.

What can happen to the MC33887 driver if there is an incoming current at the motor pin output OUT1 and OUT2 (e.g. also if an electric shock were to arrive at the motor case for ESD test)? Should go into protection and stop working?

Is there a way (using some component) to prevent currents from entering the output pins?

I thought of inserting zener diodes between the output pins and the motor but this would obviously limit the direction of rotation of the motor.

enter image description here

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    \$\begingroup\$ Why would you want to prevent the normal function of this IC (sourcing and sinking currents through the two OUT pins)? \$\endgroup\$ Commented Aug 26, 2022 at 14:13
  • \$\begingroup\$ Because if an electric shock happens to hit the motor, there is a dangerous current entering the driver and the power supply circuit that shuts down the device and stops the motor. I would just like to find a way to avoid this problem. \$\endgroup\$
    – Alinik
    Commented Aug 26, 2022 at 14:21
  • \$\begingroup\$ You will find more information under "ESD protection" topics. \$\endgroup\$ Commented Aug 26, 2022 at 14:29
  • \$\begingroup\$ How can a "electric shock" hit the motor ? (except for ESD). What scenario do you envision? \$\endgroup\$ Commented Aug 26, 2022 at 14:35
  • \$\begingroup\$ For now, the electric shock scenario is only related to the ESD tests, but it happened to me that when the motors were switched on, I measured a surge of return current in the driver that caused the circuit to go into protection. \$\endgroup\$
    – Alinik
    Commented Aug 26, 2022 at 14:50

1 Answer 1

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A stalled or heavily loaded motor may draw an inrush current that exceeds the current limit threshold of this IC (about 8 A). This can (correctly) cause the IC to detect and protect an overload.

If you power an inductive load (including a motor) and then switch it off, the inductance (and possibly motor back emf) may cause negative currents in the outputs. ICs such as this are designed for this and -- provided the current is within the specifications -- won't cause malfunction.

ESD protection on ICs such as this is generally not intended to avoid malfunction of the system, but only to avoid damage. Thus if an ESD pulse is applied, it is reasonable that the IC (possibly falsely) detects and overcurrent and protects itself. The system will recover upon restarting.

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