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Original question:

BQ25756: Please review the schematic

BQ25756: Design a charging circuit

William Eyvaz
Prodigy 10 points
Part Number: BQ25756
Other Parts Discussed in Thread: TPS25730

Tool/software:

Hello,

I am working on a charging system using the BQ25756ERRVT and have completed the schematic. I want your help with a quick review. Mainly referred to the reference schematic and altered it to the battery pack that I need to charge. Here is the battery pack specification:

Cell chemistry: "SiCoreTm Rechargeable Lithium-Ion Cell"   by Amprius  the  SA10 cell.

Cell structure:  4S4P

Input voltage:  16.2V -16.8V (requested by battery integrator) 

To minimize the firmware involvement, the setting is done by resistor setting. Additionally, I will have the I2C connected to local micro.

I am using TPS25730 PD and set it to get 20V, 3A from the AC/DC USB adaptor and feed it on the PPHV. 

Your support is appreciated!

Best Regards,

William 

6710.TI_review.pdf

  • 0
    TI__Expert 5985 points

    Hi William,

    I do not see any obvious issues with this schematic. I only have 2 concerns:

    • The TS pin is referenced as a percentage of REGN. Using REGN instead of an external LDO supply here is recommended.
    • The capacitor voltage ratings are very close to the nominal voltage. Make sure you check the voltage derating of the capacitors and place enough capacitance that the derating does not put you below our minimum capacitance for Vin and Vbat.

    Best regards,
    Michael Bradbourne

  • 0 in reply to Michael Bradbourne
    Prodigy 10 points

    Hi Michael,

    Thank you for taking the time to review the schematic and your helpful feedback. I was using the TPS25730 PD chip LDO output for the TS pin, it makes sense to use the REGN LDO output. I will check the caps and will try to add more caps if possible, the PCB size is very small and there is a space constraint that I have to deal with. 

    Best Regards,

    William