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Original question:

BQ25703A: Shipping mode

BQ25703A: Shipping mode

David Edwards15
Prodigy 130 points
Part Number: BQ25703A


In some previous threads, I saw some comment about shipping mode on the bq25703a.

(1) "bq2589x has integrated BATFET. It can cut the charge and discharge path on both direction. But, bq25703A uses external BATFET which has body diode can pass discharge current from BAT to system load. So, bq25703A's shipping mode is different than bq2589x's. bq25703A shipping mode turns off charging BATFET for certain time. At same time, the battery pack or host turns off its discharger FET."

(2) Another thread mentions that the EN_SHIP_DCHG  bit in ChargeOption1 which pulls SRN below 3.8V for 140ms. The thread describes this as a special customer request. However, I can find no information in the datasheet about a current sinking function on SRN - I would guess that there would be an open drain FET on this pin to be able to pull SRN low. At the moment, I also can't think how this would be helpful for implementing a shipping mode.


Do you have any reference material discussing established solutions to implement shipping mode with the bq25703a. I can see from comment (1) that this could be implemented independently from the charger IC - but I would prefer to avoid additional IO requirements from the host controller if possible.

Thanks,

Dave

  • 0
    TI__Prodigy 420 points
    Hi Dave,

    In BQ2589X, the battery FET is bi-directional blocking. When the shipping mode is enable, there is no leakage current coming out of the battery. At the same time, a mA level discharging current (implemented by a current source) is applied on SYS to pull down the voltage quickly, in case no system load current.

    BQ25703A follows the similar implementation, only difference is the battery FET is only single directional blocking, so before enable BQ25703A ship mode, the host needs to turn off the pack internal blocking FETs first to make sure no leakage current coming out from the battery.
  • 0 in reply to Yipeng Su
    Prodigy 130 points
    Thanks, this is clear now. I'll think about how to implement this in my application.
    Best Regards,
    Dave