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BQ24250: Start up system from missing battery

tiper liu
Prodigy 250 points
Part Number: BQ24250

Hi, All:

I am using BQ24250M with Stand alone mode. when I start up with external 5V power ( don't insert the battery ),

BQ24250M will in battery detection status, the Vsys output voltage will be instable like below waveform( the VPP is about 1V, and the frequency will be 15Hz), This voltage will be the source voltage of the system and  It will afftect system audio feature( have noise when recording audio), if we disable the charge function with /CE , the voltage is stable and the audio noise will disappear.  Do you have any suggestions?

Thanks

Tiper Liu

  • 0
    TI__Guru*** 148915 points

    Hi Tiper,

    The pulse waveform that you are seeing is expected and is part of the battery detection circuit.  When a battery is detected, this waveform is no longer present.  You can disable battery detection by disabling charge (/CE bit or pin) or disabling termination via I2C. 

  • 0 in reply to Jeff F
    Prodigy 250 points

    Hi, Jeff:

    Thanks, I understand we can disable the charge fucntion with /CE Pin or bit 1 of Reg1, if we pull /CE pin to high directly, when we insert battery, BQ24250M will not charge battery, So I want to know if BQ24250M can identify battery insert or absent, then we can set the bit1 to 1 or 0 according to the result.

    Thanks

    Tiper Liu

  • 0 in reply to tiper liu
    TI__Guru*** 148915 points

    Tiper,

    Yes, the pulse waveform on SYS indicates that the battery detection circuit has not identified a battery.  The fault registers (B0:B4) in register 1 (memory location 00) will indicate no battery detected, but only if no other fault (like TS fault) is not detected later.