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BQ25606: VBUS to charge and power

Carlo
Expert 7715 points
Part Number: BQ25606

Hi team,

Good day.

The BQ25606  can supply 5V over the VBUS when an OTG device is connected, does it mean that the VBUS can work for charging and powering devices? For example, if the BQ25606 charges the battery, and the USB port is connected to a keyboard, can it power the same VBUS that was charging the battery? Additionally, can the D+ D- pins be shared directly with the data pins and also if VBUS can power a device from that bus?

Thanks in advance for the help.

Regards,
Carlo

  • 0
    TI__Guru**** 166916 points

    Hi Carlo,

    The charger works either to charge a battery at BAT and provide voltage to system at SYS or to provide a regulate voltage at VBUS, not both at the same time.  That said, any voltage at VBUS, when in charge mode, will appear at PMID less a voltage drop of IBUS*RDSON(Q1).  Also, when in OTG mode, the SYS is the BAT voltage less IBATFET*RDSON(Q4).

    Regards,

    Jeff

  • 0 in reply to Jeff F
    TI__Expert 7715 points

    Hello Jeff,


    Thank you for your reply. Can the BQ25606 provide a voltage at VSYS and VBUS at the same time during OTG mode? Is the VSYS is still connected when OTG mode is activated? Our customer connected the VSYS to an SoC, and that SoC has an OTG USB bus, but when they plug a peripheral in the USB port as a host, they want the same USB port to provide power to the connected peripheral without cutting the power on VSYS as it powers the SoC continuously.

    Your continuous assistance is appreciated.

    Regards,
    Carlo

  • 0 in reply to Carlo
    TI__Guru**** 166916 points

    Hi Carlo,

    In OTG mode, SYS is connected to BAT by the BATFET so V(SYS) = V(BAT) - IBAT*RDSonQ4, i.e. SYS is not regulated.  Any power set to SYS will not be available for the OTG output at VBUS.  OTG can only activate if power is first removed from VBUS.

    Regards,

    Jeff

  • 0 in reply to Jeff F
    TI__Expert 7715 points

    Hello Jeff,


    Good day.

    Can the data pins that make the handshake for detecting charging sources be shared with another host? For example, Raspberry Pi OTG USB port. The idea is to be able to do the charging handshake and then use the same data ports for using the OTG capabilities of an SoC.



    Regards,
    Carlo

  • 0 in reply to Carlo
    TI__Guru**** 166916 points

    Hi Carlo, 

    Yes, but not until after the first 2 seconds after power is applied to the BQ25606 when the charger makes those pins HiZ.

    Regards,

    Jeff