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Original question:

BQ25172: BQ25172 + LM66200 Design

BQ25172: No battery status issues

Allen yang
Expert 1025 points
Part Number: BQ25172
Other Parts Discussed in Thread: LM66200

Tool/software:

Hi Team,

In the absence of battery, the BQ25172 output voltage will rise to the input voltage.

When the LM66200 output load increases, the VUSB voltage will drop.

Become powered by BQ25172, Causes system shutdown.

Is there any way to improve this problem?

  • 0
    TI__Guru* 76486 points

    Hi Allen

    The BQ25172 in a no battery condition will increase output voltage to VOUT_OVP (1.7V/cell) then turn off.  OR it could be triggering SLEEP (Vin-VOUT) which is 0.135V.

    In both cases charge will stop.

    BUT the device does not have a battery detect feature.

    Can you send a schematic for review?

  • 0 in reply to Bill Johns
    Expert 1025 points

    嗨，比爾，

    VCHG load transition will cause VCHG voltage drop

    Switch the LM66200 power supply from VIN1 to VIN2

    Causes system shutdown

    Is there any way to improve this problem?

  • 0 in reply to Allen yang
    TI__Guru* 76486 points

    Hi Allen

    Thanks for the schematic, they look OK.

    Allen yang said:

    Is there any way to improve this problem?

    We would need to disable the BQ25172 when the battery pack is removed.  Pulling the TS pin low will disable the device.  

    When is the battery pack removed from unit?  Is this a configuration for some models of devices?