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BQ25101: BQ25101 Charging error

BJ Han
Expert 2035 points
Part Number: BQ25101

Dear TI,

Application is a tag band.
1. Symptom
> When charging wirelessly, the power is supplied to the charger IC BQ25101 A2 input voltage with the secondary coil voltage between 6V and 4.3V.
   However, sometimes CHIP is not ENABLE and charging is not possible.

-. Battery Spec : 3.7V / 60mA (cut off Voltage : 2.75V)

> Battery status: Over discharged battery 1.5V ~ 1.6V
  → The product that has not been used for 4 months has the battery cut off voltage 2.75V, but it is mostly separated to 1.5V.

-. Schematic


When I charge it with such a product, it may not be charged.
Please analyze the cause. Is there a problem?

  • 0
    TI__Guru* 75656 points

    Hello BJ Han

    The schematic for BQ25101 looks OK.

    Input voltage configuration is unique but if voltage is between 4.3V and 6V device should start charge.

    Note that UVLO is 3.3V, below this point device is off.  Charge will not start until voltage is above UVLO and greater than V-Battery + 60mV (Vout + VDT).  If the input voltage is above 6.67V then OVP is active and device it turned off. 

    Things to check:

    1.) Input voltage with no load before device starts, could a light load condition put the unit in OVP shutdown preventing charging.

    2.) Input voltage may be low, below Vout + VDT and not starting charge.

    3.) Check voltage at ISET pin this can be used to monitor charge current to battery.

  • 0 in reply to Bill Johns
    TI__Guru* 75656 points

    Hi BJ Han

    Any update, are you still seeing problems with the circuit?

  • 0 in reply to Bill Johns
    Expert 2035 points

    Dear Bill Johns,
    Thank you for your attention and support.
    I solved this problem with your help.
    There was no problem on the circuit and there was a problem with the charging current due to an error in the ISET resistance value.
    Thank you again for your help.