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Original question:

BQ25703A: Application issues

BQ25703A: Application issues

lan xin
Prodigy 200 points

Part Number: BQ25703A
Other Parts Discussed in Thread: TIGER

Tool/software:

Hi，There is a problem: if IIC communication is performed before the VBUS pin of BQ25703A is fully powered on, it will result in communication failure. However, even when the VBUS of BQ25703A is fully powered on, IIC communication still fails. It is necessary to wait until the BQ25703A is fully powered on before performing IIC communication to ensure normal interaction (for example: when supplying 5V to VBUS, it takes 50ms for the VBUS pin to change from 0V to 5V. If IIC communication is performed within these 50ms, it will fail. Then, even after waiting for the full 5V supply, communication still fails. It is necessary to delay for 50ms until the VBUS is properly powered before performing communication). What is the situation? If this is the design, is there a suitable way to determine whether the BQ25703A module is suitable for communication at this time

  • 0
    TI__Mastermind 38225 points

    Hi, Lan,

    Yes, during startup, the part needs 200ms to finish the setup. It is suggested to wait 200ms when the adapter is first applied, before communication is established with the charger. 

    Alternatively, you can attach a battery, then the part is powered from the battery, you may communicate with the charger anytime. 

    Regards,

    Tiger

  • 0 in reply to Tiger Zhou
    Prodigy 200 points

    Hi，Can we determine whether the BQ25703A can communicate based on the voltage level of the CHRG_OK pin? According to the specification, a high voltage level indicates that VBUS is at the operating voltage. So, if we detect a high voltage level before communicating, it should be normal. Is my operation correct? Or do we need to wait for a delay of 200ms after VBUS is powered on before communicating? Additionally, could you please explain the functional application scenarios and circuit connection design of the CHRG_OK pin? Thank you!

  • +1 in reply to lan xin
    TI__Mastermind 38225 points

    Hi, Lan,

    CHRG_OK is ON in 50ms after adapter plugin, so you still need to wait for 150ms. The CHRG_OK means the input voltage presents, Okay to charge. 

    Regards,

    Tiger