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BQ25713: Schematic sanity check

Jeffrey Blum1
Prodigy 90 points
Part Number: BQ25713
Other Parts Discussed in Thread: BQ77915, BQ34Z100-G1,

Hello,

I'm designing a LiPo charger for the first time and I'm using a BQ25713 charger along with a BQ77915 battery protection IC and a BQ34Z100-G1 gas gauge. My system uses a 3S2P battery (the Cx pins are the LiPoi cell pads) charging from USB-C PD; is there anything I'm missing in this schematic?

Battery.pdf

  • 0
    TI__Expert 3320 points

    Hi There,

        Below is my suggestions for BQ25713 schematic. We do have a TI EVM reference design attached. Please follow our reference design in case there is  any missing.

        1, REGN output capacitance is suggested 2.2uF and VDDA input filter cap should be  1uF.

        2, C36 should be populated with 1uF cap.

        3, SDA and SDL need to be pulled up to 3.3V through 10kohm pull up resistor.

        4, If C37-C44 are the only Output capacitors for this system(No poscap connected to VOUT anymore), you need to add 2*33uF POSCAP at output for stability  consideration.

    Regardssluubt8b.pdf

  • 0 in reply to Shishuo Zhao
    Prodigy 90 points

    Hi Shishuo,

    Sorry, I forgot to mention that there are 3.3k pull-up resistors on the I2C lines but they're on a different board next to the processor that controls the overall system. Where did the POSCAP thing come from? I don't remember anything like that in the example schematics?

    Also, does the rest of the schematic (the TI parts anyways) look good? The charger is the core component but everything else is important too.

    Thanks,

    Jeffrey

  • 0 in reply to Jeffrey Blum1
    TI__Expert 3320 points

    Hi Jeffrey,

       The POSCAP is included in our TI EVM reference schematic attached above and marked below. If there is any down stream converter after our charger, then the input capacitor for second stage converter can also be counted here for our charger output capactance. All we need to make sure there is 2*33uF effective POSCAP capacitance along the charger output distribution line.

       For the  BQ77915 battery protection IC and a BQ34Z100-G1 gas gauge device related schematic, I would like to invite expert at TI battery gauge team to help review. Thanks.