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BQ25618: VBHOT REGN off

Ambroise Suter
Expert 4110 points
Part Number: BQ25618
Other Parts Discussed in Thread: BQ25611

Section 8.3.2 of the BQ25618 state the following:

If only the battery is present and the voltage is above depletion threshold (VBAT _DPLZ), the BATFET turns on and
connects the battery to the system. The REGN stays off to minimize the quiescent current.

 

If REGN is going to be off when there is no USB power, then how can the system decide shut the Booster off at elevated temperatures:

Also there seems to be a typo on page 3: ", the battery starts to discharge the battery until the system power requirement is met. This supplement mode prevents overloading the input source". The same error (?) is in the BQ25611.

Thank you and best regards,

Ambroise

  • 0
    TI__Mastermind 31180 points

    Hi Ambroise, 

    Section 8.3.2 that you mention is in reference to when no input source is connected to the BQ25618. The battery discharges to power the system load and REGN is off to maximize battery life. 

    When the device is in boost mode REGN will be on, as mentioned in section 8.3.3.1, and the device will have the hot and cold temperature protections enabled. 

    Thank you for pointing out the typo, it should say "The battery starts to discharge until the system power requirement is met." I will work to have this adjusted on the datasheet. 

    Best Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    TI__Expert 4110 points

    Hello Garett,

    Do I understand correctly, that the UVLO comperator only detects UVLOZ for a VBUS rising edge. A falling edge on VBUS does not affect the REGN LDO?

    Best regards,

    Ambroise

  • 0 in reply to Ambroise Suter
    TI__Mastermind 31180 points

    Hi Ambroise, 

    Section 7.6 of the datasheet states that if VBUS falls too low (TYP 3.15 V) the REGN LDO will turn off. 

    Regards,

    Garrett 

  • 0 in reply to Garrett Kreger
    TI__Expert 4110 points

    Hello Garrett,

    Thank you for your response, that leads us to the original question:

    If REGN is going to be off when there is no USB power, then how can the system decide shut the Booster off at elevated temperatures?

    Best regards,

    Ambroise

  • +1 in reply to Ambroise Suter
    TI__Mastermind 31180 points

    Hi Ambroise, 

    When in boost mode the device, including REGN, is powered by the battery voltage. For example, when boost mode enable conditions are valid removing input power transitions the device between charge mode and boost mode. REGN will not shut off.

    My response above in regards to the REGN LDO turning off when VBUS falls too low is for the scenario when boost mode is disabled. 

    Regards,

    Garrett