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BQ25070: Charging Pin indication

Abhishek singh
Expert 2000 points
Part Number: BQ25070

We are using LED  as in EVM Board for indicating charging and Not Charging. But LED is not glowing till we are not drawing  280 mA (with default configuration).   I have few  questions 

1) What will be minimum current for which IC will drive CHG pin Low.  

2) Does it depend on the setting of charging current?

3) Suppose I program charging current as (max current ) . How charging pin will  behave with  decreasing current ?

  • 0
    Expert 2000 points
    Hi Team ,

    Any update ?
  • 0 in reply to Abhishek singh
    TI__Mastermind 20170 points

    Can you use the same test condition on our EVM to see if you can duplicate on the EVM?

    /CHG is an open drain output. When charging a battery in precharge or fastcharge mode, the CHG output is pulled to GND. Once the BAT output reaches the overcharge voltage threshold, CHG goes high impedance to signal the battery is fully charged. The CHG output goes low during battery recharge cycles to signal the host.

    Note that ICHG must be below 5mA.

  • 0 in reply to Jing Zou
    Expert 2000 points

    Hi  Jing ,

    I don't have EVM. Please find the attached schematic. During my  tetsing battery was not connected . I  am draawing current only through load . Does testing without batterry will create problem . I am assumng that IC will consider load current as charging current . sch_501-1-00529-a24.pdf

  • 0 in reply to Abhishek singh
    TI__Intellectual 1980 points

    Hello

    You should use battery or electronic load(CV mode) to test, load cannot be only a resistor. Because charger will detect the voltage of VBAT to decide how to charge. Please refer to p10(charge process chart) in the datasheet.

  • 0 in reply to Kerry Song
    Expert 2000 points
    Hi Song and Jing ,

    We today i inserted batterry , batterry is getting charged and LED is glowing as per expectation . But suppose i removed batterry while battery is charging . CHG # pin goes high , but on again re insertaion LED is not glowing .
  • 0 in reply to Abhishek singh
    TI__Intellectual 1980 points

    Hello,

    Do you mean when you plug in the battery again, the LED is not glowing? 

    If so, it's a normal phenomenon for the part.

  • 0 in reply to Kerry Song
    Expert 2000 points
    Hi Song,

    Thanks for update . I have understanding that whenever batterry is getting charged , i will be refleted by the CHG pin. When I am doing above mentioned procedure (reinsertion thing ) battery is getting charged by same current +current cunsumed by charging LED.

    On probing i find out the voltage at CHG pin is Vpull up- Vf(led). Why this thing is happening ?

    Does mosfet of CHG pin is not behaving as it supposed to?
  • 0 in reply to Abhishek singh
    TI__Expert 3186 points
    Hello team ,

    TO put this in brief ,
    The LED charging indication LED glows once the Battery starts charging .
    However during this time if lets say i remove and reinsert the battery the charging LED doesn't glow back again on reinsertion of battery.

    We connected a ammeter and saw that after reinserting the Charging current is flowing properly into the battery

    The CHG pin is sitting at 1.9V , which is very strange for a open drain connection .
    Has the internal mosfet gone in a active region rather than being either in cut off/Resistve mode ?
  • 0 in reply to Shreenidhi Patil
    TI__Intellectual 1980 points

    Hello

    Your issue is a normal phenomenon for this part.

    Could use blow solution to solve it. 1.pull the TS terminal low to let CHG pin go reset, after you plug in battery as above condition. Then, recover TS pin to normal connection. And the IC will work normally. MCU in end-equipment could help to realize it. 2. Also cycle input power(plug out VIN, then plug in VIN) could let CHG pin go reset.

    Regards