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BQ25703A: bq25703A

Ty Le Van1
Prodigy 200 points
Part Number: BQ25703A

Hi TI supports,

I am using bq25703A EVK and I observed weird behavior as below

- I used DC power supply to provide power input for EVK board. When I decrease 12V input gradually, at about 10 and 9.30V, bq25703A shutdown.

- I kept the these input voltages, turn off power supply and on again, bq25703A had output

- I increased input voltage, bq25703A had output

Could you please explain me these behaviors?

Thanks,

Ty

  • 0
    TI__Expert 3320 points

    Hi Ty,

         This is normal behavior because of VINDPM feature. You can read REG0x0B/0A(Input voltage register setting), it should be around 9.3V~10V.

          VINDPM is an input voltage limit routine, which monitors and controls the input voltage by using a resistor divider between R1 and R2 and comparing it with VREF_VINDPM, which is set by VINDPM_DAC. This is useful for third party adapter which we don't know current limit. Because of the output voltage droop effect based on load current , by limit input voltage we can establishing a max current level limit on the unknown adapter input. 

         BQ25703A  by default set VREF_VINDPM(Input voltage register setting)= Steady state VIN(12V)-1.28V.  If the input voltage drops more than the InputVoltage register allows, the device enters VINDPM and keep same input current by reducing the charge current to give load priority to system current. If you continuous reduce VIN then converter should shut down.  You can always reduce REG0x0B/0A(Input voltage register setting) below 9V then the converter should not shut down at 9.3V~10V input voltage.

    Regards

  • 0 in reply to Shishuo Zhao
    Prodigy 200 points

    Thank for information

    Regards,

    Ty