BQ27421-G1: Soc% when battery is disconnected and SRX pin is connected to battery charger IC

Lahari Sankati

Part Number: BQ27421-G1

In BQ27421YZFR-G1A when SRX pin is connected to battery charger IC and the Battery is removed from fuel gauge BAT Pin and there is an input of USB charger current from battery Charger IC to fuel gauge through SRX pin.

If battery is disconnected, would the charger supply voltage drive BQ27421 LDO?
What would be the SoC reported from BQ27421, in this case? Note: battery is disconnected

over 4 years ago

0 Nick Brylski over 4 years ago

TI__Mastermind 19195 points

Hi Lahari,

If charger is providing enough voltage on the BAT pin the device and LDO will be on. (This will be very close in voltage to SRX.)
An SOC value can be reported, it will depend on the voltage the charger is providing.

Best,

0 Lahari Sankati over 4 years ago in reply to Nick Brylski

Prodigy 30 points

Thanks for confirmation.
Does it mean that fuel gauge chip is not able to differentiate if the it is powered from BATTERY or CHARGER supply?

Basically I want to indentify from Fuel Gauge that battery side voltage is not available. And then report to MCU on battery is disconnected/discharged.

0 Kang Kang over 4 years ago in reply to Lahari Sankati

TI__Mastermind 24870 points

The gauge will not be able to differentiate. To us it is just a power above our operating condition.

0 Lahari Sankati over 4 years ago in reply to Kang Kang

Prodigy 30 points

Thanks Kang Kang got the information

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BQ27421-G1: Soc% when battery is disconnected and SRX pin is connected to battery charger IC