[BCM20736S] Is it OK to apply voltage to GPIO pins while power is OFF?

[WaSu_1697556]

Hi,

Could someone answer to the following question?

Are there any issues to supplying voltage to GPIO pins while BCM20736S is powered off ( No power supply to VBAT)?

It's something that is not explicitly mentioned in the datasheet.

[BoonT_56]

Are you asking this question in the context of ESD? What is the value of the applied voltage?

ESD on module BCM20737S

[WaSu_1697556]

Hi btta,

Actually one of our end customers asking this question and according to them the context is not of ESD.

Applied voltage is 3.3V.

Best,

Wataru Sugimoto

[BoonT_56]

Is there a reason why a voltage is applied to the pins?

I don't think the 3.3V will damaged the chip, since it can survive those ESD voltages.

[WaSu_1697556]

Hi btta,

Sorry my question might have been a bit ambiguous.

Best,

Wataru

[Anonymous · Accepted solution]

Applying a static voltage to an unpowered chip is always critical and has little to do with the ESD ratings:

1. If the input current does not exceed the rating of the protection diode, it is viable. Eventually you have to add a serial resistor to limit this current.
2. Especially when applying this scheme to more than a single pin: be aware that this current goes to the supply rail - providing some ill-defined voltage to your chip even when the "normal" power supply is off.