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BQ24167 shuts off charging when the mounted board is exposed slightly to sunlight

Muthukumar S
Prodigy 100 points
Other Parts Discussed in Thread: BQ24167

hi,

i am using BQ24167 in a solar charger. I disabled the TS input by connecting the DRV out of Bq24167 to TS input. So i didn't use thermal protection for battery charging.  

When i am testing my board for solar charging covering the board in a transparent plastic case in sunlight, the Bq24167 stops charging the battery, there is no way that the junction temperature reaches above to 120C  for thermal shutdown.  i don't know why its stop charging the battery?

Even though my board is covered in a plastic case, is there a possibility that the junction temperature shoots up?

note the setup was kept in sunlight for 10 min only.

  • 0
    TI__Genius 13700 points

    Hello Muthukumar,

    There are a number of factors that will influence the operation of the device.

    What is your input voltage, battery voltage, and charge current?

    Also a schematic of your system would be convenient to review for some of the other device settings.

  • 0 in reply to Ryan May
    TI__Guru**** 166996 points

    What is the VINDPM setting?  It needs to be set to 75-80% of the solar panel open circuit voltage in order to extra the maximum power from the panel without collapsing the panel.

  • 0 in reply to Ryan May
    Prodigy 100 points

    Dear Ryan,

    Thank u for ur reply,  Answers for ur Question and Schematic are mentioned below. 

    Solar Input Voltage is 5V, Battery Nominal voltage is 3.7V ( Li-ion) and configured solar current setting is 1.5A, At that time of my testing, charging current from solar panel is 450mA. USB1-3 configured as 010 by uC. 

    Also the battery is only charged to 25 to 30% at that time.

    FYI: When i test the board with AC adaptor/Bench Supply as input to solar port, the Charger IC never shutoff charging in the middle. It shut off after battery is fully charged.

    Only in the external environment(solar), it shutoff charging in the middle.

  • 0 in reply to Jeff F
    Prodigy 100 points

    Dear Jeff,

    Solar Input Voltage is 5V, Battery Nominal voltage is 3.7V ( Li-ion) and configured solar current setting is 1.5A, At that time of my testing, charging current from solar panel is 450mA.

    Vin_DPM = 4.44V,  a resistor divider network of 26.7k and 10k whose center tapped to VDPM input. Note: Rtop is 26.7K

     

  • 0 in reply to Muthukumar S
    TI__Guru**** 166996 points

    What are the voltages at the IC's USB, IN, TS and BAT pins when charging stops?  Does charging stop abruptly or does the charge current slowly decrease to 0?