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Original question:

BQ25703A: CELL_BATPREZ dual functionality issue

BQ25703A: BQ25703A Battery detect

Jonas
Intellectual 540 points
Part Number: BQ25703A

Dear Wang:

I search and see your reply about battery detect.

1st: title is"BQ25703A battery detection question":e2e.ti.com/.../654386

in this part: you descripte that: "bq25703A CELL_BATPRES pin: LOW indicates battery present, HIGH indicates battery absent. "  I think it's wrong as this pin define in datasheet. It should be low indicates battery absent, and high indicates present. Right ? 

2nd: title is" cell_batprez dual functionality issue:https://e2e.ti.com/support/power_management/battery_management/f/179/t/635339?tisearch=e2e-sitesearch&keymatch=BQ25703A%20BATTERY%20DETECT

in this part, you said: "CELL_BATPRESZ pin is pulled below VCELL_BATPRESZ_FALL to indicate battery removal." This talks about an external circuit needs to pull down CELL_BATPRESZ pin to let bq25703A to know the battery removal.

So I want ask：does BQ25703A have any pin can tell MCU battery is unpluged ?  how BQ25703A detect battery remove or unpluged.

Above is my confuse about you discussed before. and above is myself question found on my customer board.  my question is also about battery detect. below picture is our register setting.

My customer want BQ25703A inform MCU that when battery is removed. we found 0x22 bit 1 can indicate BAT removal acitve. but when we plug and unplug battery, this register value have no change, the status not change. as your description, whether we need pull low cell_batterypresz pin by external circuit , then we can see the change  at the 0x22 bit1 ? if yes, BQ25703A cannot detect battery remove or plug by itself. need external device control. If it's right, when BAT removal acitve register can use ? If it's wrong, please help check whick register is setted wrong in below picture and how we can see the 0x22 bit 1 change to inform MCU battery status. 

 


 

BQ25703A Battery Detection question

  • 0
    TI__Guru 56650 points
    1. I fixed the original post. For BQ25703A's CELL_BATPRESZ pin, it is battery cell selection pin for 1–4 cell battery setting. CELL_BATPRESZ pin is biased from VDDA. CELL_BATPRESZ pin also sets SYSOVP threshold to 5 V for 1-cell, 12 V for 2-cell, and 19.5 V for 3-cell/4-cell. When CELL_BATPRESZ pin is pulled below VCELL_BATPRESZ_FALL by host controller or other circuit, that indicates battery removal. The device exits LEARN mode, and disables charge. REG0x05/04() goes back to default.
    Yes. Pulling low by host indicates battery absent. Please be ware, pulling low by host. BQ25703A doesn't do the battery detection. The host controller or other circuit do the battery detection.
    2. BQ25703A doesn't have any pin to tell MCU battery is unplugged. BQ25703A doesn't detect battery remove or unplugged. BQ25703A also needs this info from the host or other circuit to tell the battery removal.
    3. When you want to use 0x22 bit 1 to indicate BAT removal, we need to pull low cell_batterypresz pin by external circuit. And then, we can see the change at the 0x22 bit1. Yes, BQ25703A cannot detect battery remove or plug by itself. cell_batterypresz is an input pin, not output pin. We need external device control. To check "PROCHOT status register" bit, I think we need to enable that PROCHOT function in "PROCHOT option 1" register.
  • 0 in reply to Wang5577
    Intellectual 540 points
    Wang:

    Thanks a lot.
    3. we had enabled Prochot option 1 register when we test.

    Jonas zhang