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TPS65217 USB and BAT question

Logan Lin
Intellectual 340 points

HI

Block diagram of the power path and battery charger as below, I can't find detail for BATDET, AC detect, USB detect, please help to clearify that how it works.

 

Another question about USB and VBAT,

The USB supply path switch ON/OFF which depend on VBAT(Battery) is present or absent  

VBAT present : USB supply ON

VBAT absent : USB supply OFF

Is this situation normal? 

  • 0
    TI__Mastermind 31580 points
    Hi

    I will move your post to the PMIC forum where one of my colleagues will answer it.

    Regards

    Peter
  • 0
    TI__Expert 3740 points

    The details of  input power detection is under "POWER PATH USB/AC DETECTION LIMITS" in the electrical characteristics table.  

    Logan,

    That's not exactly how it works. The way the power path chooses if a specific supply is valid or not( ac or usb) is dependent on the battery.  

    If the battery is present, meaning if the voltage on the battery pin is greater than UVLO,  then AC will be valid if the voltage on the AC pin minus the voltage on the battery pin is greater than 190mV minimum.

    If the battery is not  present, meaning if the voltage on the battery pin is less  than UVLO,  then AC will be valid if the voltage on the AC pin  is greater than 4.3V minimum.

    This is also true for the USB pin.

    To detect removal of the AC or USB has been removed when there is a battery present the voltage on the AC/USB pin minus the voltage on the battery must me less than 125mV maximum.

    without a battery the voltage on the USB/AC pin must be less than the UVLO+ 200mV (typically).

    Keep in mind also if AC is valid then the PMIC will take power from the AC pin as long as that pin can support the power consumption needed. If AC is not valid then it will try USB next, only when AC and USB are not valid will the power path choose the battery input as a source of power to the device.

    I hope this helps. 

    Janice

  • 0 in reply to Janice Escobar
    Intellectual 340 points
    HI Janice

    Thanks your clear explanation.

    If the datasheet can adding description that you described, that will be better.

    I geuss the USB is less than 4.3V when battery not present, and when battery present, VAC pin minus the VBATpin is less than 190mV

    so the supply is from battery now.

    but i need to double check from customer's board whether followed these conditions or not,

    Thank you again!