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DRV8873S-Q1EVM: Startup error when VM is 5V

Tomoaki Yoshida91
Genius 5255 points
Part Number: DRV8873S-Q1EVM
Other Parts Discussed in Thread: DRV8873

Hi team,

There is a case that the DRV8873 does not operate when VM turns on with low voltage setting.

We want to use that VM is 5V.

Although it does not operate when VM is started at 5V, it operates at 5.1V.

DRV8873 is active even if VM is started up at 6V and gradually lowered to 5V or less.

There seems to be a threshold in the vicinity of 5V and it seems that it will not begin to operate unless the VM once exceeds this threshold.

Are there restrictions on startup in this device or this EVM?

Best regards,

Tomoaki Yoshida

  • 0
    TI__Guru** 114905 points
    Hi Yoshida-san,

    We will investigate and reply soon. It may be that the reverse voltage protection is affecting this threshold.

    Did you measure VM at the testpoint labeled VM or at the pin of the DRV8873S-Q1? The testpoint is really VBAT and may be a diode above VM at low voltage. The VM label will be corrected.
  • 0 in reply to Rick Duncan
    TI__Guru** 114905 points
    Hi Yoshida-san,

    The reverse protection circuit reduces the DRV8873 VM voltage by ~600mV. When the input voltage is 5V, the DRV8873 VM voltage is 4.4V.

    After the input voltage increases above 5.1V and the device is not in sleep mode, the charge pump enables the protection FET. The DRV8873 VM voltage then matches the input voltage.