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BQ25898: TS Pin set up

Hailiang Zhang
Expert 6645 points
Part Number: BQ25898
Other Parts Discussed in Thread: BQ27Z561

Hi Team,

Could you pls help with below questions?

1,  Is it necessary to collect the temperature through TS Pin and NTC, if the temperature  is read through the host, and is it feasible to control the charger IC?
2  1S2P battery pack usually has several temperature probes (NTC)?
3，Both the fuel gauge and the charger IC need to get the cell temperature. If the battery pack only provides one TS Pin, how to deal with the TS Pin of the fuel gauge and the charging IC?

Thanks,

Hailiang

  • +1
    TI__Mastermind 25805 points

    Hi Hailiang, 

    1) It is not necessary to use TS pin and NTC for BQ25898. You can use 2 10kohm for TS resistor network to have TS voltage always be in normal operation range. It is feasible to have the host adjust charging parameters based on temperature it reads, but be aware if customer wants to follow JEITA guidelines using an NTC with TS pin is easiest way. 

    2) If your battery pack has several temperature probes you should only connect 1 to TS pin on BQ25898.

    3) This will depend on the fuel gauge being used. As mentioned in 1) the BQ25898 does not need battery NTC connection to function. If temperature monitoring is required by fuel gauge then connect the temperature probe on pack to gauge product. 

    Best Regards,

    Garrett

  • 0 in reply to Garrett Kreger
    TI__Expert 6645 points

    Hi Garrett,

    Thanks for your answer. 

    Is it ok to use the TS pin to monitor the voltage at the TS Pin of the gauge? 

    Regards,

    Hailiang

  • +1 in reply to Hailiang Zhang
    TI__Mastermind 25805 points

    Hi Hailiang, 

    I am not an expert on TS pin biasing on the BQ27Z561, but from taking a quick look at the datasheet I do not recommend connecting the battery pack NTC to both BQ25898 and gauge device in parallel.

    The BQ25898 compares V_ts against internal thresholds referenced to internal REGN supply to control the charge cycle based on battery temperature. Having the NTC also connected to power rail in BQ27Z561 could cause problems. 

    Best Regards,

    Garrett