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no power output for UCD9222+2*UCD7242 when in < 0 deg C

stonenut lin
Prodigy 160 points
Other Parts Discussed in Thread: UCD9222, UCD7242, UCD9240, UCD9222A
Hi Ti;
we are using the UCD9222+2*UCD7242 to power the TI DSP 6670 for CVDD and 1.0V.
Now we met an issue that there are no power output from the UCD9222+2*UCD7242 when in < 0 deg C. However, when the temperature go to about 3C, it work ok.
It seem that there is no powergood signal output from the UCD9222 when in < 0 deg C.
The UCD9222 and 7242 's spec show they can work in -40C to 125C range.but why we can not work ok under the 0 deg C. Could you help to give some comment for this issue?
BTW. on the fusion GUI monitor page, I found the voltage on aux ADC(1-4) is not the same as I use the DMM measure on the board. Is that mean I need to do calibrate for this part to correct it?
Thank you!
  • 0
    Prodigy 10 points

    Hi,

    I had the same problem whit UCD9240 + UCD7242, this is due to the current monitor of the driver that it isn't constant at temperature variation.

    I solved

    • Using a 10K on IMON;
    • Decreasing the working frequency from 1.3MHz to 750KHz.
  • 0
    TI__Genius 13700 points

    Does the controller throw any fault codes when it stops operating below 0C?

    If there is no output there will be no PowerGood signal.

    There is nothing in the FW/HW which would limit the operation at or below 0C.  I would check to ensure the parts are mounted down correctly without any voids.

    The values at AUXADC1 and AUXADC2 should be correct, the problem would be with AUXADC3 and AUXADC4 which are not properly initialized in the UCD9222 FW and will not return the correct values.

    There is a newer FW version part which is in production but not released on the TI web yet, it is the UCD9222A controller which is compatible with the existing UCD9222.  The UCD9222A returns the correct values for AUXADC3 and AUXADC4.  New FW version controller's are released with a new P/N rather than as a rolling change to the existing device.  Both the UCD9222 and the UCD9222A will be available moving forward. 

  • 0 in reply to Brad
    Prodigy 160 points

    The powerup issue is fixed by lengthen the reset time to 200ms now. but base on the spec, this original reset time we used should be ok, but it can not work under the 0 deg C really. why?