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BQ24171: Adapter Voltage Headroom Needed for Charging

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?

  • 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

  • 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