BQ27421-G1: GPOUT Pin

Mitchell

Part Number: BQ27421-G1

Hi Team,

My customer has a question regarding the GPOUT pin on the BQ27421-Q1.

In the datasheet it says that GPOUT should be pulled to VDD even if it is not used. Right now in their system they have this pin pulled high to the BQ27421-G1 1.8V rail and going to a GPIO on their host MCU. When the system is in shutdown (MCU off) the fuel-gauge stays ON and this 1.8V rail from the fuel-gauge remains high. Unfortunately this voltage leaks back into their system via the GPIO on the MCU. What happens if they do not keep GPOUT pulled high with the fuel gauge on? Will it cause unexpected chip behavior, or just increased current draw?

Thanks,
Mitchell

over 6 years ago

0 Onyx Ahiakwo over 6 years ago

TI__Guru* 76230 points

Hi Mitchell

Connecting the GPOUT to the gpio pin of an mcu is to allow the mcu toggle that pin in the event of a shut down. I wouldn't recommend having an application without that.

thanks

Onyx

0 Mitchell over 6 years ago in reply to Onyx Ahiakwo

TI__Expert 4915 points

Hi Onyx,

Thanks. The question wasn’t if we can disconnect the gauge GPIO from the MCU, but rather is it OK to have this IO pin left floating or pulled down when the MCU is powered down.

I see in the datasheet the 10k pull-up recommendation, I was just curious why this this is required? Operation, leakage, etc?

Thanks,
Mitchell

0 Onyx Ahiakwo over 6 years ago in reply to Mitchell

TI__Guru* 76230 points

It is the operation of the chip. The pin is open drain, and leaving it in a tristate condition could cause as unwanted outcome to the operation of the chip. Same for pulling it low.

thanks

Onyx

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BQ27421-G1: GPOUT Pin