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BQ27750: BQ27750 TPS61072 schematic

Part Number: BQ27750

Hello TI team,


I plan to use the BQ27750 for a battery monitoring of the 18650, and now I have some puzzles about the schematic.

[ Question ] 
1. I integrated the TPS61072 5V boost chip and BQ27750 on a single board. Is the BAT_PWR (PACK+ in BQ27750 IC ) of the schematicas the input of the TPS61072 IC or the VCC_BAT(Cell BAT+) as the input of the TPS61072 IC? The schematic is as follows, which design is more reasonable, or you have better suggestions.
2. If VCC_BAT is the input to the TPS61072 IC, what should I do with PACK+PACK- in the BQ27750 schematic?

3.  If it is convenient, please help check if the schematic has any deficiencies.

Thank you in advance.

Ting

  • A TI expert will assist you
  • Ting,

    1) If you connect it to VCC_BAT Then the 5V power output would always be active, but the current would not flow through the senseR and it would be an unaccounted for load. This would lead to problems for the gauge since the battery will have current being drained which will lead to an incorrct DOD. It is recommended it is connected to BAT_PWR.

    2) Pack+/Pack- is the input to your system load and where you connect the charger. in your diagram BAT_PWR is the Pack+. Your pack- is the left side of R12 (which should not be grounded)

    Thanks,
    Eric Vos
  • Hi Eric Vos,

    Thank you very much for your answers, the first question I have already understood, will take your advice.

    For the second question, forget to explain, I don't need to charge the battery. So I think if the TPS61072 IC is connected as a load to both sides of the PACK + - (load + - ), the PACK- (load) should be grounded. Does my understanding have any errors?

    Thanks,
    Ting
  • No it should not be the same ground as the IC. You are shorting out the current sense resistor if they are the same ground. The pack- should be connected to the ground of you load and should not be the same ground as the IC. pls see the EVM reference schematic.
    thanks
    Onyx