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DRV8871: Input Transient Voltage Protection

Part Number: DRV8871

Hello TI,

From DRV8871 data sheet '7.3.5 Protection Circuits', its clear that DRV8871 has got Undervoltage, Overcurrent and Thermal Shutdown protection.

Has DRV8871 also got inbuilt Surge & Input Transient Voltage Protection? Or is it recommended to connect an external TVS diode on Vm Power Supply Pin?

(We understand DRV8871 has internal body diodes on Motor Driving OUT1 & OUT2 pins, eliminating the need for external flyback diodes. We would like to know if similar inbuilt Transient Voltage Protection is also available on Vm Power Supply pin)

Thanks,

Ashok D

  • Hi Ashok,

    The DRv8871 does not have built in Surge and Input Transient Voltage protection.

    It is recommended to connect surge protection externally. The TVS can be connected to the VM power supply, but also can be connected to the OUTx pins in the case the voltage surge is initiated at the motor.

  • Thank you  for the clarification.

    We request more clarification on the second option you suggested please. We see DRV8871 has got integrated flyback diodes on OUTx pins. Do they not provide the required Surge Protection on the Motor Side? Do you still recommend adding a Bi-Directional TVS diode on OUTx pins?

    (In our case, the 12V Power Supply Source connected to DRV8871 VM pin is almost at 100 meters distance. So we are considering a TVS Diode on VM pin to provide Overshoot Protection in-addition to Surge protection.)

  • Hi Ashok,

    The body diodes provide the a path for the current recirculation.

    But please consider an ESD event when designing a system. The DRV8871 includes ESD protection for HBM and CDM, but not an ESD event when operating.

    A TVS or some other type of ESD suppression on the outputs may help there.

  • Thank you again  for the detailed explanation. We are now considering installing a TVS Diode on OUTx pins as-well.

    So, do you recommend installing TVS diodes on either sides of DRV8871 (Unidirectional TVS on Input Side and Bidirectional TVS on OUTx pins) or would it be sufficient to install a Bidirectional TVS on OUTx pins alone?


    Regards,

    Ashok

  • Hi Ashok,

    We typically deal with the connections from the DRV8871 to the motor, but not the system protection. Most customers add system protection on their own.

    Please refer to http://www.ti.com/lit/an/slyt492/slyt492.pdf and http://www.ti.com/lit/an/slva680/slva680.pdf for an example of TVS connections.

    The link discusses ESD events, which should be considered at the system level when the system is operational.

    There are also many other articles available on line to assist. A search for 'iec tvs diodes "motors"' should produce many articles and links to TVS manufacturers.

  • Thank you  for sharing the links. We will go through and select the appropriate protection.

    Regards,

    Ashok