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BQ21040: #CHG pin doesn't work well

chentsu chung
Mastermind 6180 points
Part Number: BQ21040

Hi,

Here are two question about #CHG:

1.  While plug in DC source, the #CHG doesn't goes low, but the charging current is correct.

what is the condition that #CHG goes low I can check,  only the charging current?

2. For the 600mAh battery, and  fast charging current set to 570mA---the CC stage is very fast, but even through 2Hrs passed, the CV doesn't go to termination, charging current is still 90mA, how to improve the charging time?

Thank you.

  • 0
    TI__Guru* 75656 points
    Hello
    Can you send a schematic of the circuit?

    1.) CHG pin will only go low for the first charge cycle, later recharges will not show on the CHG pin.
    2.) Short CC phase and long CV phase does not sound right. What is voltage on the battery and could it be in thermal regulation?
  • 0 in reply to Bill Johns
    Mastermind 6180 points

    Hi Bill,

    Thanks for you response

    1.) CHG pin will only go low for the first charge cycle, later recharges will not show on the CHG pin. 

     A: This is not in recharging. it's at the first time plug in AC

    2.) Short CC phase and long CV phase does not sound right. What is voltage on the battery and could it be in thermal regulation?

     A: I attach the log date for battery voltage for your reference.

    Charging Data 180601.xls

  • 0 in reply to chentsu chung
    TI__Guru* 75656 points
    I double checked this in the lab with bq21040 EVM and everything works as expected. Took a closer look at the /CHG pin behavior with TS pin pulled high and in a TTDM but could not trigger the condition you are describing.

    Somethings to check on:
    1.) How is the TS pin configured, is it under the control of a micro? Can you test with it grounded with 10k?
    2.) Is a system load connected to OUT in addition with to the battery?