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bq25504 sporadic turning off of VSTOR

Martin Schmidt93
Intellectual 320 points
Other Parts Discussed in Thread: BQ25504

We're buying from a supplier a thermogenerator-powered  product that contains the bq25504.

Out of the units produced in 2014, our customers returned a small percentage. These units had died for no apparent reason.

We analyzed these failures and found VSTOR turned off though there is more than enough charge on VBAT and the cell there is low-impedance and healthy.

The failures immediately returned to normal operation when harvesting energy, so I assume they have not been harvesting any energy from the time when they broke down to the time when customers returned them to us.

So far, I don't see this effect in products built in 2015.

Is there a known issue with older bq25504-chips ?


Any help would be welcome.

Martin

  • 0
    TI__Guru**** 166996 points
    The only issue we found was a noise sensitivity on the VSTOR pin that caused the IC to stop the main charger and reenter cold start. The fix was to lower the size of the filter capacitor on VSTOR from 0.1uF to 0.01uF and also improve its placement so that it is as close as possible between the VSTOR and VSS pins, even if that meant using vias to connect to the VBAT pin.