BQ27441-G1: LDO not turning on/I2C not responding

Trailblazer

Part Number: BQ27441-G1

I've integrated the BQ27441-G1 into my design, which I believe to be correct and following the recommended application. However, it does not turn the LDO on when the battery is plugged in. I'm confused as to why as I have seen other designs very similar to mine that are working perfectly.

over 2 years ago

0 Dominik Hartl11 over 2 years ago

TI__Guru 61766 points

The schematics look correct. Please check that the PCB footprint was designed correctly (pin numbers match the TI datasheet info).

0 Trailblazer over 2 years ago in reply to Dominik Hartl11

Prodigy 30 points

I have checked the footprint against the datasheet and everything is laid out correctly. I'm at a loss as to the next step here.. Thanks for your response.

0 Trailblazer over 2 years ago in reply to Dominik Hartl11

Prodigy 30 points

What is the criteria for the LDO to come on? Perhaps I'm doing something else that is causing it to stay off? Additionally, is the BQ27441 able to respond to I2C commands without the LDO on?

0 Dominik Hartl11 over 2 years ago in reply to Trailblazer

TI__Guru 61766 points

The LDO will come on when the voltage on BAT exceeds 2.45V (see datasheet, table 8.7). The gauge will not respond on the I2C bus unless the LDO is on (VDD approx. 1.8V). Please disconnect everything from VDD (including the capacitor) to debug your system.

0 Trailblazer over 2 years ago in reply to Dominik Hartl11

Prodigy 30 points

I appreciate the response. I found that removing the PU on GPOUT caused the LDO to turn on. I then tied GPOUT to 3.3V in my system instead of pulling it up to the battery voltage and everything remained working. The battery voltage was around 4.01 which is outside of the acceptable range according to the datasheet, which likely was causing issues.

0 Dominik Hartl11 over 2 years ago in reply to Trailblazer

TI__Guru 61766 points

Thanks for the update. Was VLIPO turned on before VBATT?

0 Trailblazer over 2 years ago in reply to Dominik Hartl11

Prodigy 30 points

Yes VLIPO is directly from the battery, VBATT is VLIPO after passing through the fuel gauge.

0 Dominik Hartl11 over 2 years ago in reply to Trailblazer

TI__Guru 61766 points

GPOUT is an open drain output and can be pulled up to VBAT. I don't think that this is the true reason why the LDO didn't start up.

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BQ27441-G1: LDO not turning on/I2C not responding