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BQ25798: device not charging, "poor source"

Nicholas Carley
Expert 8185 points
Part Number: BQ25798

Hello,

Customer is experiencing a "poor source" situation but this condition is not clearing once the poor source is resolved.

Its supposed to retry every 7 minutes, but its not getting itself out of this mode after the issue is resolved. 

Are there any register settings that would cause this?

Nick

  • 0
    TI__Mastermind 29935 points

    Hi Nick,

    What supply are you using and is it capable of delivering power to the BQ25798? Can you please give me a register dump (with the ADC enabled and included)?

    Sincerely,

    Mike Emanuel

  • 0 in reply to Michael Emanuel35
    TI__Expert 8185 points

    The input is solar, so the device is entering poor source on a highly cloudy day but it isn't able to get out of this mode once the clouds are gone and its back to being sunny. The solar panels can provide the correct voltage, is there a minimum current needed?

    I've attached a register dump when the device is in the stuck in the poor source state. I emailed you the schematic for reference as well.

    bad_charger_force_reset.log

    • The charger seems to work fine, but then after some time (maybe a few days) we see the charger shut off and not charge.
    • This state is 'sticky' in that if we apply/remove external power (to either the PV USBVBUS inputs) does not get the charger out of this state
    • Doing a register reset does not get the charger out of this state
    • Pulling the batteries and disconnecting the input charge voltage (full system power down) does seem to clear this condition most of the time.
    • The voltages on the charger seem to look good:
      • +BATTIN @ J8-1 = 3.04V
      • VBUS @ J9-1 = 5.28V (OK)
      • VAC2 @ J9-2 = 0V (OK)
      • VAC1 @ J10-2 = 5.28V (OK)
      • USBVBUS @ J52-2 = 5.28V
      • CPEN @R395 = 0 (OFF)
      • PV_EXT @ J51-2 = 0 (pulled down)
      •  J10-1 = J10=2 = 5.28V (FETs on)
      • CHGR_EN @ R146 = 0V (enabled)

    Nick

  • 0 in reply to Nicholas Carley
    TI__Mastermind 29935 points

    Hi Nick,

    I am having trouble understanding your input setup. According to your register dump and measurements above VAC1 is present which is the USB. However, the solar input VAC2 is not present in the registers nor the measurement. Do you have USB input connected while using the solar panel? Also, I did not see the ADC measurements when the solar panel is connected and the charge is not happening. Could you please record all the registers in the observed condition?

    Sincerely,

    Mike Emanuel