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BQ25890H: Inquiry about using OTG function in other system than USB

Charles Jeon
Expert 2975 points
Part Number: BQ25890H
Other Parts Discussed in Thread: BQ25895

Hi Team.

My client wants to design a system such as:

1) Normally, 12V voltage is input from the external(using adapter), and the battery is charged to 3.8V at this time.

2) When the external power is cut off, the voltage of the charged battery is stepped up and output at 5V / 1.5A for use in the internal system.

3) I would like to use the OTG function of BQ25890H to perform the above.

Can the BQ25890H perform these functions without any external control?

Please refer to the picture below

  • 0
    TI__Guru*** 143910 points

    Hi Charles,

    bq25890H requires host software to enter OTG.  The only IC in the family that automatically enters OTG when VBUS is removed (after a short delay) is bq25895 but its 5V output comes from PMID not VBUS as it was designed for power bank applications.  Would that IC work for you application?

  • 0 in reply to Jeff F
    Expert 2975 points
    Hi Jeff
    Thank you for quickly response.

    1. Is bq25895 capable of OTG without I2C or Host Control?
    2. In the block diagram, PMID is connected to VBUS through the internal FET.
    If 12V is applied to VBUS, will PMID output 12V?

    Thank you.
  • 0 in reply to Charles Jeon
    TI__Guru*** 143910 points

    Regarding 1, yes, bq25895 automatically enters OTG mode after VBUS voltage drops below UVLO threshold.

    Regarding 2, yes, if 12V is applied to VBUS, PMID will see 12V.