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BQ76930: BQ76930 regout

Big Bill
Expert 1980 points
Part Number: BQ76930

Dear  All:

    I design the  17S BMS with BQ76930, In my  application, when the BQ76930 is wake up, the  regout can output voltage,  I  use the  REGOUT  to  enable  the system DC-DC IC EN pin, I find the Regout  would  be 

pull down  immediately  as shown in the following figure. can  , if  i  disconnect the Regout from the  DC-DC En pin , the regout  output  is normal. can you  help me to  solve the problem, Thanks

  

  • 0
    TI__Guru 54715 points

    Hi Bill,

    The REGOUT can only supply a little over 20 mA.  If the DC-DC has a higer load or causes the total load on REGOUT to approach the short circuit current of REGOUT the output will drop.

    Another thing to check is the resistance in the REGSRC path, if it was sized for a low current and the DC-DC enable is adding enough load that REGSRC drops, REGOUT will drop also. 

    A person would expect an enable to be high impedance, but check the specifications on the DC-DC and measure its load.

  • 0 in reply to WM5295
    Expert 1980 points

    Dear  ：

         as shown in the following figure,the regout_B pin is connect with the circuit, I think the load is small because of connect enable Pin. I think the Regout can  supply  enable pin source current . Do you have any questions about my understanding? Thank you for your suggestions.

         

  • 0 in reply to Big Bill
    TI__Guru 54715 points

    Hi Bill,

    I would guess there may be a short in the REGOUT net near U1, somewhere after you disconnect it.  The data sheet for the regulator does not show a load current for EN, seems it must be low.  You will likely need to measure it to find out what is wrong.