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BQ24171: Adapter Voltage Headroom Needed for Charging

Intellectual 470 points

Replies: 2

Views: 78

Part Number: BQ24171

What's the voltage headroom required from the adapter voltage to the battery charge voltage (8.4V in my 2 x Li Ion case)?  I didn't see it in the datasheet.  I'll be using wireless power source for charging, so it's important to know the minimum "adapter" voltage needed.  Thanks.  

Side note - it looks like TI does not make a 15W Qi power receiver that outputs 9V or more.  Is this correct, or did my search miss something?

  • Guru 81295 points

    Hi Steve,

    This charger's minimum input voltage  (PVCCmin) for fast charging can be derived from its max duty cycle=97% before pulse skipping, which would be 8.4V/0.97 = 8.7V.  Even if below 8.7V, the charging will attempt to charge, just much more slowly, as long as PVCCmin > VBAT+VSLEEPmax=8.4V+150mV = 8.55V. 

    TI does not have a 15W Qi receiver that outputs 9V.  The highest output voltage for our Qi receiver is 7V.

    Regards,

    Jeff

    Please click "This resolved my issue" button if this post answers your question.

     

  • In reply to Jeff F:

    Thanks for the quick and complete answer, Jeff.  That means I can use a Qi receiver that outputs 9V (or more) for my application (although I would prefer 12V to give margin).  Also thanks for verifying TI's Qi receiver options.

    - SteveP

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