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BQ25713B: Input current sense resistor

Di Ma
Intellectual 420 points
Part Number: BQ25713B
Other Parts Discussed in Thread: BQ25713,

Hello team,

I have changed the input current sense resistor from 10 mohm to 20 mohm to increase the resolution of input current reading from 50mA to 25 mA (ADCIINCMPIN() (2B/2Ah) register).

What other changes I have to do for other registers related to input current (IIN_HOST(0F/0Eh) and IIN_DPM(25/24h)) ? Do I also have to halve their LSB?

Regards,

Dmitriy

  • 0
    TI__Expert 4285 points

    Hi Dmitriy,

    Datasheet spec is based on 10mohm. Other values are not recommended.

    Best Regards,

    Linhong

  • 0 in reply to Linhong Qin
    Intellectual 420 points

    Dear Linhong, please read section 9.6.6.1 of datasheet of BQ25713 (provided below) that says that 20mohm input sense resistor can be used for higher regulation accuracy, which is my case since I'm treying to find the Maximum Power Point of a PV solar panel based on the input current and BUS voltage information.

    Also please read the ChargeOption1 register which has a configuration bit RSNS_RAC which supports 20mohm configuration. However I'm not sure what is the purpose of this configuration bit?

  • 0 in reply to Di Ma
    TI__Expert 4285 points

    Hi Di,

    Sorry about the confusion. You are correct! BQ25713B supports 20 mohm sensing. Yes, you need to set Register bit RSNS_RAC=1, and half all your calculations when you set up current settings(you don't have to change voltage settings).

    Best Regards,

    Linhong

  • 0 in reply to Linhong Qin
    Intellectual 420 points

    Dear Linhong,

    To sum up, for an input current sense resistor (RAC) of 20 mohm:

    1. The LSB of IIN_DPM(25/24h) is 25mA? What about register ofset (value for 0x00), is it 50mA or 25mA?

    2. The LSB of IIN_HOST(0F/0Eh) is 25mA? What about register ofset (value for 0x00), is it 50mA or 25mA?

    3. The LSB of ADCIINCMPIN(2B/2Ah) is 25mA and full range is 6.375 mA?

    Regards,

    Dmitriy

  • 0 in reply to Di Ma
    TI__Expert 4285 points

    Hi Dmitriy,

    All current values will be half'ed. 

    Best Regards,

    Linhong