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BQ25703A: MPPT charging

Aaron Lal
Prodigy 160 points
Part Number: BQ25703A
Other Parts Discussed in Thread: BQ24650, , BQ25798

Hello TI,

I'm trying to implement MPPT charging with this chip.

I have run into difficulty controlling the input voltage and measuring the input current in the MPPT sweep.

  1. To what register do I write to control the input voltage (i.e. from the solar panels)?
  2. Which register or ADC do I read to measure the input current?

I am already familiar with how to read ADC registers.

Kind regards,

Aaron

  • 0
    TI__Expert 4780 points

    Hello Aaron,

    BQ25703A is designed for USB PD applications and doesn't have features designed for solar charging. Have you considered BQ24650 (Buck only) or BQ25798 (Buck-Boost)? 

    For BQ25703A, the InputVoltage() register (0B/0A) sets the input voltage limit (IINDPM) below which the charger will reduce the output current to maintain that input voltage. It is defaulted to VBUS-1.28V upon powerup.

    Input current ADC can be read back in register 2B (ADCIINCMPIN). You need to set bit 4 of ADCOption() register 3Ah to enable IIN ADC sampling. The LSB is 50mA.

    Thanks,

    Khalid

  • 0 in reply to Khalid Bairuti
    Prodigy 160 points

    Hi Khalid,

    Thanks for your advice. We'll stick with the BQ25703a and use ICO instead of trying to implement MPPT.

    Best regards,

    Aaron