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DRV8886AT: TVS Diodes Required?

Matthew Watson18
Prodigy 70 points
Part Number: DRV8886AT

When using the DRV8886AT in fast decay mode I would expect power supply pins VM to have a lot of noise and voltage spikes.  With a power supply of 28V +/-5%, will voltage suppressors be needed next to the driver?

  • 0
    TI__Guru** 114905 points
    Hi Matthew,

    TVS diodes are typically not required next to the driver for operation. The DRV8886ATEVM does not have them.

    TVS or other protection circuits may be required for voltage spikes (ESD for example) at the motor terminals.
  • 0 in reply to Rick Duncan
    TI__Prodigy 70 points
    Hi Rick,

    Thanks for the response. Since during fast decay the phase motor winding is pumping current into the VM power bus (up to 2A), depending on components and design it will cause some voltage spike on VB.

    Since page 32 in www.ti.com/.../drv8886at.pdf states “The voltage rating for bulk capacitors should be higher than the operating voltage, to provide margin for cases when the motor transfers energy to the supply.”, I am wondering why one would worry only about failing bulk capacitors and ignore the fact that there or other components that will be exposed to the same voltage spike (including DRV8886AT, ceramic decoupling capacitors as well as possibly hundreds of other components sharing the same VM power bus).
  • 0 in reply to Matthew Watson18
    TI__Guru** 114905 points
    Hi Matthew,

    All components on the VM bus should be considered as you pointed out. A properly sized and voltage rated bulk cap can minimize the voltage spikes on the VM bus.
  • 0 in reply to Rick Duncan
    TI__Expert 3100 points
    Hi Rick,

    Thanks for the pointer. I'm currently working with Matt on this question. So will the bulk capacitors be enough to take care of discharge? Will adding a TVS diode on the input pins compromise the device performance in any way? If not then I guess we can add the diode to be on the safe side.

    Thanks,
    Sepeedah