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XIO2001: VDD_15_COMB to high

Yossy Goldenberg
Prodigy 240 points
Part Number: XIO2001

Hello,

I have about 10 PCI cards, (based on xio2001),some working properly and some not working. From the measurements I made, I see that in those who do not work, the voltage VDD_15_COMB starts at 1.5 V, rises to 2.0 V and sometimes drops to 1.8 V. All other input voltages, and the voltages the component produces are normal.

my device setup is as follows:

VDD_33_AUX not used and pulled down using a 10K resistor.

GRST floating.

We tried to improve the soldering, but it did not help.

Please Advise,

Regards,

Yossy Goldenberg

  • 0
    TI__Guru* 93670 points

    Hi Yossy,

    1). I am assuming you have checked PCIe 100MHs reference clock and and compared with working board?

    2). If you are using BGA pkg, any potential GBA balls that could be shorted under the part?

    3). On the other hand, if we are using QFN pkg it might be worthwhile to swap part between working and non-working board - if possible.

    Regards,, nasser

  • 0
    Prodigy 240 points

    Hi Nasser,

    Thank you for your help.

    1- Yes, there is a reference clock and it's the same as for working card.  More then that, the non working one, generates the 33Mhz PCI clock as well, but the clock amplitude is about 4V PCIR=3.3V).

    2 &3: we are using a TQFP package. I will try to replace one, but It will take some time since we have a holiday this week.

    The high voltage appears after #PERST rises. The computer then tries to perform a number of additional PERST cycles, then stops, and loads the computer without the card. 

    I have about 6 working cards and 4 non working ones.

    Thank you!

    Regards,

    Yossy Goldenberg

  • 0 in reply to Yossy Goldenberg
    Prodigy 240 points

    Hi Hi Nasser,

    Another update is that the high voltage accrues only when the  PCIe clock is applied to the card. when the power up cycle, which i have described above, is in process (VDD_15_COMB=2.0V). when the PC fails to configure the card, and no clock is applied to the card, then the VDD_15=1.5V again. 

  • 0 in reply to Yossy Goldenberg
    TI__Guru* 93670 points

    Hi Yossy,

    PCIe clock is the reference for internal PLLs and thus power up all the logics. When you get a chance to swap the part then we would know if the problem moves with the device or board. It owuld be good to monitor current consumption in working versus non working boards as well.

    Regards,, Nasser