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BQ51010B: How to restart charge cycle if device left on charger for long time?

Part Number: BQ51010B

On Page 16 of the data sheet, there is the following diagram of start-up flow:

Specifically there is the first bubble I find interesting which states "TX Powered without RX Active." However, according to WPC spec and contrary to my interpretation of this flow diagram, there is nothing the RX can do to evade the TX from extending a ping... What I'm investigating is the case when RX battery has already been completely charged and issued an EPT Charge Complete packet to TX, and then left for some time on the charger while the battery is depleted. Is it possible that:

(A) The TX does extend additional pings, which RX cannot stop it from doing, but the RX continue sending an EPT response to the ping until the next cycle of removing RX from TX, and re-placing RX onto TX


(B) The TX is controlling this, and does not extend additional pings to the RX until it's detected the next cycle of removing RX from TX, and re-placing RX onto TX

Kind thanks,


  • Hello Billy
    The TX will extend the ping in response to a reply from the RX. Digital ping will start at 80ms and transition into power transfer. The RX can stop this by sending EPT or not replying. Digital ping will repeat at a 500mS to 5 sec rate.
    BQ51010B is a 7V power supply and can power a battery charger. To support charge complete EPT and turn off the TX it will need input from the battery charger. Also to restart charge and enable the TX it will need input from the the charger again.

    Many TX will detect that the RX has been removed and replaced, then try to restart communications and power transfer. This can be done with a low power analog ping or digital ping that will power the RX.