DRV8800 / Capacitor on VREG

Hi Satoshi-san,

We are currently investigating this and will reply soon.

Hi Rick-san,

Thank you for your response. I'm looking forward to your update.

Best Regards,

Sonoki

Hi Rick-san,

I'm waiting for your response. Your support will be appreciated.

Best Regards,

Sonoki

Hi Satoshi-san,

Thank you for reminding me.

The VREG can be left floating. If used, VREF should only be used as a voltage reference. VREG cannot have an external load on it.

Sorry for the delay.

Hi Rick-san,

Thank you for your response. You mean that the VREF can be used for reference voltage (For example ADC's Vref) and then the additional decoupling capacitor on VREG may be needed. Is my understanding correct?

Best Regards,

Sonoki

Hi Satoshi-san,

It is not recommend. VREG is a resistor divider from the internal regulator. The VREG voltage will change based on current pulled from the pin.

From page 11 of  the DRV8800/8801 datasheet:

"This output represents a measurement of the internal regulator voltage. This pin should be left disconnected. A
voltage of approximately 7.5 V can be measured at this pin."

Leaving the pin floating is recommended.

Rick-san,

I understand that VREG pin should be left open. But I'm not sure the reason why you also show the decoupling capacitor on VREG as optional and when it should be added.

Best Regards,

Sonoki

Hi Satoshi-san,

There is no condition where you should add the capacitor. If you desire, adding the optional capacitor creates a low pass filter on the VREG pin.

Adding the capacitor has no effect on device operation.

Hi Rick-san,

I guess the additional capacitor may be needed to reject high frequency spike noise on VREG because VREG is used for Low-Side Gate Supply. So in case of drive high load current, high frequency spike noise will be occurred and then additional capacitor can help to reject it.

Best Regards,

Sonoki