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BQ24780S: Shipping Mode

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Prodigy 30 points
Part Number: BQ24780S

What is the Shipping Mode? When should SRN pin discharge current?

  • 0
    TI__Genius 16185 points
    Hi,
    The shipping mode's purpose is to avoid battery power dissipation during product shipment process. It will be helpful to keep battery energy for long while.
    You can proceed ship mode when you plan to ship your product out.

    Thanks
  • 0 in reply to Paul Yeh
    Prodigy 200 points

    In 8.2.2.3 of datasheet, we can see that:“ Some packs may wake up again if the voltage on SRN pin stays above pack UVLO too long.”

    In my opinion, battery will constantly deliver the current to system through body diode  when the system is totally shutdown,   so that Vsys will be pulled up, then some packs may wake up.

    For this reason, we should enable the shipping mode to discharge the current of SRN. And without the current from battery, Vsys will down to 0 to minimize the quiescent current.

    I don't know if I'm right.

    If so,  for there are only 140ms to discharge current in the shipping mode,  should we enable the shipping mode frequently? Or , when we enable the shipping mode, IC will automatically discharge current when needed? And what is the threshold to discharge current.

     

     

  • 0 in reply to user5779852
    TI__Genius 16185 points

    Hi,

    This charger's shipping mode function should work with battery pack's internal MOSFET. Before you enable shipping mode, you should send command to battery pack to turn off internal MOSFET to force Battery disconnect to charger. But because there still bias voltage existed in battery connector to re-force battery pack turn on again. So enable shipping mode can force BQ24780S to discharge residual voltage via SRN pin.

    You don't need to enable shipping mode frequently when customer use normally. Just for product ship from your factory.

    Thanks