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BQ25150: Load Connection on PMID vs Directly battery

Chirag Panchal1
Prodigy 70 points
Part Number: BQ25150
Other Parts Discussed in Thread: BQ24075, TPL5111

Hi, 

I am planning to use BQ25150 battery charger IC. My new design includes RF module (GSM 2G) and Microcontroller with other digital circuitry.

I am planning to attach MCU and all other digital load on PMID Pin  as it has 1.5 A sufficient current capable. but as my GSM 2G fall back will consume >2A pick current so I can not connect that on PMID pin. Can I connect GSM RF module directly to Battery, instead of PMID pin ?  so my load will be divided  - one(MCU and other digital) from PMID output and one (GSM) from BAT pin (directly from battery).

Can I configure my circuitry connection like this above mentioned manner?

Regards,

Chirag Panchal

  • 0
    TI__Mastermind 21590 points

    Hello,

    It is not recommended that you connect your load directly to BAT because this could prevent the charger from properly terminating charge and the device will not enter true shipmode. 

    Are you able to use a charger like the BQ24075 in your design?

  • 0 in reply to Raheem
    Prodigy 70 points

    Well I can use suggested charger like BQ24075 as suggested by you, but my main pain point is I am designing the lowest power consume device. where I can not afford more quiescent current to consume.

    Can I put TPL5111 nano power timer between battery and BAT pin of charger ? so that battery will be disconnected for the time my application will not require to run ? this way I can save quiescent current to not allowing to waste from battery ? I have one doubt if I will put MOSFET in between battery and BAT pin of charger IC - that mosfet will be gated by TPL5111 timer, while application will be operated from battery (discharging) all is fine. BUT what about in charging power path ? will my battery charge in that case ? or I need to put bi directional mosfet or two separate mosfet on for discharging circuit and one for charging path ? any idea? 

    what about using latest charger IC  BQ25616 ?

  • 0 in reply to Chirag Panchal1
    TI__Mastermind 21590 points

    Chriag,

    What is your load profile? Is the 2A DC or periodical?

  • 0 in reply to Raheem
    Prodigy 70 points

    mostly load profile will be - 20 to 30 mAs constant from MCU and other peripherals, when packet will be transmitting its NB IoT module - so 200mA on top of 20 to 30mAs, but when NB IoT network will not present (in India) it will be 2.5A pick for some milli seconds (have not practically verified up to how much time 2.5A pick will present) then after successful transmission - done signal from MCU to TPL5111 timer so MOSFET will cut off battery path from load again.

  • 0 in reply to Chirag Panchal1
    TI__Mastermind 21590 points

    If the duration of the NB IoT is in the milliseconds, this should not have any effect on the battery charging. You should be able to connect that load to the battery directly. However, the design will need to ensure the NB IoT is not enabled when the battery is below UVLO setting. 

  • 0 in reply to Raheem
    Prodigy 70 points

    thanks raheem,

    well BQ25611DRTWR resolve all my queries and issue. I need to bare some cost on money wise due to 2G fall back and maximum power saving is my key points. Lets see, once in all over country NB IoT implemented, 2.5A current peak will not be there, then I will change part number. Thanks.