BQ24171: Operation with TTS pin tied to AGND.

Maurizio Bonelli

Part Number: BQ24171
Other Parts Discussed in Thread: BQ28Z610

Hello,

in our application, the charger is used to charge a large battery whose state is managed by an on-board gauge: I mean BQ24171 and BQ28Z610 are both on the same board and embedded with the cell pack.

Due it is the gauge which ends the charge, I am wondering if I can tie the TTS pin to AGND because all safety is performed by the fuel gauge. The output of the charger is directly connected to the PACK of the fuel gauge.

I would like to do so, because if the powered apparatus is ON, when the charge is ended the charger can continue to power the PACK to supply the host apparatus also if I know this is not a proper use of the charger.

Could the operations of the BQ24171 be affected in some way if the TTS pin is tied down?

Thanks a lot!

Maurizio

over 6 years ago

0 Jeff F over 6 years ago

TI__Guru**** 165986 points

Hi Maurizio,

If the TTC pin is pulled low, both charger termination and safety timer are disabled. This means that the charger will continue to provide current to and regulate the voltage at the battery. The BQ28Z610 gauge/protector combo can report when the battery is full and/or how long charge has taken but it would be up to the gauge/protector to terminate charge current flow into the battery if that is desired.

Regards,
Jeff

0 Maurizio Bonelli over 6 years ago in reply to Jeff F

Expert 1400 points

Thanks a lot.

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BQ24171: Operation with TTS pin tied to AGND.