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BQ51051B - How to know charging has been started ?

Hariprasad C R
Intellectual 485 points
Other Parts Discussed in Thread: BQ51051B, BQ51050B, BQ51021

I'm planning to use BQ51051B for my Li-ion battery by wireless charging.But I need some clarification on two items.

1.Does the BQ51051B provides some kind of pin/some mechanism to indicate battery charging has been started ? (I need to do some process in my MCU once charging has started, so I need to know whether it has started or not)

2. Is there any way in BQ51051B to know the current battery voltage level?

  • 0
    TI__Genius 14890 points

    Hi,

    1. The bq51051B CHG pin is used as an indicator for charging.  It is an open drain output.  Pull it high and when the BAT pin is enabled, it will pull low.

    2. The bq51051B measures the battery voltage, which is how it determines which charge mode to be in.  If the battery is below V(LOWV) it will be in pre-charge mode.  If between V(LOWV) and V(OREG) it will be in fast charge.  At V(OREG) it will enter taper mode.  There is not a method for reading that voltage by the MCU.

    Regards,

    Dick

  • 0 in reply to Dick Stacey
    Prodigy 30 points

    Hi! 

    I have additional question. Is it possible to determinate by some pin that device is placed on a power transmitter? I want to determinate moment that device will be removed from charging pad after charge complete (CHG pin is open in this state).

    Thanks! 

  • 0 in reply to Aleksandr Shumakov
    TI__Genius 14890 points

    Aleksandr,

    The bq51050B does not have a feature to note that it is on the pad.

    The bq51021 does have a feature "pad detect" that does give that indication.  See the PD_DET pin in the datasheet for more information.  The bq51021 is a wireless power receiver and does not have the charge feature that the bq51050B does.

    Depending on the transmitter, the system will attempt to reestablish power transfer periodically.  When it does, the RECT powers up and determines if the OUT/BAT pin should be powered or not.  Using that may enable you to find a method to implement your function.

    Regards,

    Dick