BQ24070: Battery Absent

Amber Tom

Part Number: BQ24070

I am using the BQ24070 to charge a Li-Ion 3.7V battery. The Stat1 output will normally blink an LED (~1.5Hz) when I apply external power with the battery absent. I have a handful of units that the Stat1 output stays low all the time and never turns off the LED. Any ideas on what could cause this?

over 3 years ago

0 Anthony P Pham over 3 years ago

TI__Mastermind 23220 points

Hi Amber,

Are you using a resistor in series with the LED? Do you have the LED pulled up here? For reference, I've snipped the EVM schematic for the BQ24070.

0 Amber Tom over 3 years ago in reply to Anthony P Pham

Prodigy 200 points

Hello Anthony,

Yes, the LED is in series with a resistor. That stat1 connection is also pulled up by a 10k resistor.

+5V is generated by a boost converter from Vout on the BQ24070.

0 Anthony P Pham over 3 years ago in reply to Amber Tom

TI__Mastermind 23220 points

Hi Amber,

It looks like you have to voltages on either side of the LED. What are the reasons for these?

For the ones that are not working, can you provide a waveform of the BAT pin, STAT1 pin, STAT2 pin, and the two voltages there when a battery isn't present?

Best Regards,

Anthony Pham

0 Amber Tom over 3 years ago in reply to Anthony P Pham

Prodigy 200 points

Hello Anthony,

The Stat1 connection is open collector, so it requires a pullup resistor. The STAT1 pin is always low. The STAT2 pin is always low. BAT pin reads 4.2V. All readings are steady state.

-Thomas

0 Anthony P Pham over 3 years ago in reply to Amber Tom

TI__Mastermind 23220 points

Hi,

Would you be able to provide the voltage waveform on the BAT pin?

Would it be possible to try without the voltage +5V present to put it in a similar setup as the EVM schematic I've attached?

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

Power management

Power management forum

BQ24070: Battery Absent