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BQ24133EVM-715-15V: STAT Pin Function

David Bjorn
Prodigy 40 points
Part Number: BQ24133EVM-715-15V
Other Parts Discussed in Thread: BQ24133EVM-715-5V

We have been working with your BQ24133EVM-715-15V evaluation kit for a 2S Lithium Ion configuration.  We adjusted ISET to lower the charge current (~0.75A) but otherwise the configuration seems standard.  The powerpath and charging seems to be working perfectly.  But we are having an issue with the STAT line; for what ever reason the STAT pin is held open (never closing - during charging or toggling - with battery fault or removed).  Any ideas why the STAT line would be held open? 

We have JP2 installed and we have confirmed the proper direction of D1 (manually grounding the line does activate the LED).

  • 0
    TI__Guru*** 148655 points
    Hi David,

    That is strange. Our EVM vendor follows the user guide steps and is supposed to confirm LED operation. I am not aware of IC returns for STAT failures. When you grounded the LED, did you ground at the STAT test point, TP19?
  • 0 in reply to Jeff F
    Prodigy 40 points
    Hello Jeff, yes if I ground the STAT pin externally through the test point it does turn the LED on. My issue is around the STAT pin function, it seems like it is held open and I cannot get the chip to close or toggle STAT under any condition (charging, battery disconnected, battery fully charged, etc.).

    We are in the middle of our board design and I would like to verify this function. The only key difference I noted between the EVM and our design....our design follows the datasheet reference which pulls up the line to Vref (~3.3V)...where the EVM appears to pull it up to the main supply voltage which in our configuration is around 12VDC.
  • 0 in reply to David Bjorn
    TI__Guru*** 148655 points
    David,

    Do you have the capability to change the IC on the EVM? I will test an EVM in my lab as well.
  • 0 in reply to Jeff F
    Prodigy 40 points
    It is possible we could change the part but it would be "difficult" especially with the thermal pad. As long as you can confirm for me the STAT pin functions properly on your EVM, we should be good.
  • 0 in reply to David Bjorn
    Prodigy 40 points

    Hello Jeff, did you have a chance to test your EVM to verify the STAT pin function? 

    Secondary question, assume the STAT pin works well on your EVM.  Can you tell me more about the STAT pin state during a fault condition, it states in Table 3 that if the charge is suspended, input overvoltage, battery overvoltage, timer fault, battery absent that the STAT pin will "BLINK" do you have any definition for what "BLINK" is?  What frequency, dutycycle?  Our programming team needs details.

  • 0 in reply to David Bjorn
    TI__Guru*** 148655 points

    Hi David,

    I apologize for the delay.  Attached is a plot showing my testing of the BQ24133EVM-715-5V.STAT changes with charge termination to recharge and then starts blinking at 0.5Hz typical when TS fault occurs.

    regards,
    jeff