bq24630: Precharge timer also disabled when TTC is low?

John M

Other Parts Discussed in Thread: BQ24640, BQ24630

Hello,

The safety timer is disabled when the TTC pin is taken low or pulled to VREF. Is the precharge timer also disabled when TTC is low or pulled to VREF? We weren't sure after reading the datasheet.

We have an application where an ultracapacitor module or LiFePO4 battery pack might be connected and the caps could take longer than 30 minutes to reach V-lowv threshold.

If there was a way to lower the V-lowv threshold of 0.35V, that would also help a lot. Down to zero volts would be great.

Thank you!

JohnM

over 10 years ago

0 Smriti B over 10 years ago

TI__Expert 5565 points

John,

I would recommend the bq24640 if you plan on charging a super capacitor. The bq24640 allows charging from 0V whereas the bq24630 does not (no way to change this in the bq24630).

I will get back to you about the precharge timer being disabled when TTC is pulled low.

0 John M over 10 years ago in reply to Smriti B

Expert 2135 points

Good point about using the bq24640 instead, thank you.
Looking forward to your response regarding TTC disabling!

JihnM

0 Smriti B over 10 years ago in reply to John M

TI__Expert 5565 points

John,

Precharge timer is NOT disabled when TTC is low. It's always a fixed 30-minute timer that's there to make sure a faulty battery isn't plugged in.

0 John M over 10 years ago in reply to Smriti B

Expert 2135 points

Hello Smriti,
That's what we were thinking. Thank you very much for checking into this!

JohnM

Power management

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bq24630: Precharge timer also disabled when TTC is low?