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BQ24115 - Status Pin (STAT1)

Florent BERT
Prodigy 70 points
Other Parts Discussed in Thread: BQ24115

Hello everybody,

I currently use BQ24115 product on my design. 

I have validate almost 95% of functionalities ... but one functionality is not working.

When Charge is not enable, STAT1 is OFF

When Charge is enable (Precharge Or Slow Charge Or Fast Charge), STAT1 is ON.

But, when charge is enable and battery voltage is above threshold (fixed by FB pin 13), charging stops (good things) but STAT1 stay to ON. 

Due to the BQ24115 datasheet, STAT1 must change to OFF because of "Charge Complete", is it right ?

Is there something wrong on my comprehension ?

Thanks in advance for any reply,

B.R,

Florent

  • 0
    TI__Genius 13700 points

    Hello Florent,

    When you say charging stops what is the state of STAT2? Table 1 contained in the datasheet on Pg. 17 show the two STAT pins to both toggle when a charge is complete.

  • 0 in reply to Ryan May
    Prodigy 70 points

    Hello Ryan,

    Thanks for your reply.

    Due to BQ24115 version, STAT2 is not availaible for this chip.

    But you are right, my configuration is that i have to toggle from ON to OFF. But when charge is complete, this pin stay to OFF...

    For me, "charge complete" means this use case :

    - 1) Battery Voltage level below 8.2V due to my configuration & Charge Enable => Charging in progress => STAT1 ON.

    => Works well because STAT1 is ON and current is present to charge battery (Precharge or Slow Charge ...)

    - 2) Battery level rise over 8.2V => Charging complete => STAT1 OFF. 

    => Current to charge battery stops so battery level is well understood but STAT1 stay to ON.

    I hope i did not confuse you ...

    B.R,

    Florent

  • 0 in reply to Florent BERT
    Prodigy 70 points

    Any idea to help me ? :)

    B.R,

    Florent

  • 0 in reply to Florent BERT
    TI__Genius 13700 points

    Hello Florent,

    I apologize for missing the fact that the STAT2 is not present on the BQ24115.

    So the charge current is zero at the battery regulation voltage and STAT1 is still on? Are you testing with an actual battery or are you simulating a battery to expedite your testing.

    Does the STAT1 pin turn off for other cases from Table 1 such as over voltage on the BAT pin?

    I will touch base with some of my colleagues for their ideas on what might be happening here.

  • 0 in reply to Ryan May
    Prodigy 70 points

    Hello Ryan,

    You are apologized ;)

    Yes the current is zero and STAT1 still on.

    I am testing with a personnal board (push-pull to dissipate current + voltage follower to force the image of battery voltage).

    My battery regulation is 8.2V due to feedback resistor divider. 

    When CE_N is OFF, STAT1 is OFF => OK

    When CE_N is ON  and i apply lower than 8.2V (8V), current is 200mA (because of slow charge conf) and STAT1 is ON => OK

    When CE_N is ON  and i apply 8.2V, current is zero and STAT1 is ON => KO ...

    When CE_N is ON  and i apply 9.6V, current is still zero and STAT1 is OFF => OK ... according to overvoltage ?

    It's maybe due to my personnal board and because it's not a real battery but i don't think that ...

    B.R,

    Florent

  • 0 in reply to Florent BERT
    Prodigy 70 points

    Hello,

    In addition, when there is no battery connected and when i enable charge, STAT1 must be OFF (Table 1).

    But STAT1 is ON in my case ...

    Below screen of BAT level when charge enable and battery not connected :

  • 0 in reply to Florent BERT
    TI__Genius 13700 points

    Hello Florent,

    Sorry for the delay.

    That is strange that you are seeing a waveform that is similar to the battery detection waveform when you using the BQ24115 which does not have the integrated detection algorithm as discusses on Pgs. 19-20

    Since there is no battery detect on the BQ24115 it makes sense that when charging is enabled it will attempt to charge and it will indicate that it is trying to charge.

    Is there anything else present on the battery rail when your simulated battery is disconnected?