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BQ25638: Charge with Solar Power Source Simulator

eajon chen
Prodigy 145 points
Part Number: BQ25638
Hello ti team，
     We found out when we were doing Charge with Solar Power Source Simulator testing。
At 4.1V, the Vbus input 10-30mA current, BQ25638 to charge the battery current is 0mA, this phenomenon also appears in EVM。
I would like to know why bq25638 cannot be charged at 10-30mA if the following conditions are met？Attached is our test report。
1 VBUS > VBAT + VSLEEPZ
2 VVBUS < VVBUS_OVP
3 EN_HIZ = 0
4 VSYS < VSYS_OVP
5 TJ < TSHUT
  • 0
    TI__Prodigy 170 points

    Hi Eajon,

    Does the test start with a battery at 4.1V or is the battery voltage gradually charged up to 4.1V?

    Best Regards,

    Katherine Huckabay 

  • 0 in reply to Katherine Huckabay
    Prodigy 145 points

    The test start with a battery at 4.1V.

    Thank you !

  • +1 in reply to eajon chen
    TI__Prodigy 170 points

    Hi Eajon,

    BQ25638 is a 100mA-5A charger and is not designed for reliable charging startup when the adapter voltage is close to the battery voltage with low input current.

    I recommend to either:

    1. Increase the adapter voltage.  The power in to power out ratio is too low to startup with low adapter current.  This is why the device can successfully startup into charge when the battery is at 3.6V with the same adapter current. 
    2. With the same adapter voltage, begin charging at a lower battery voltage (<= 3.8V) and slowly increase to 4.1V for your test.  The device will continue to charge after a successful startup at a lower battery voltage.

    Best Regards,

    Katherine Huckabay