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UCD9248 FLT fault and SRE always down

Segura Marcelo
Prodigy 20 points
Other Parts Discussed in Thread: UCD9248, UCD7230

Hi I have been working with Xilinx FPGA kintex 705. This board has 3 ucd9248. One of them on rail 4 stop working and I cannot fixed. I hope with your support I can solve the problem.

If you want to take a look on the schematics here is the link: 

https://casper.berkeley.edu/wiki/images/1/10/Kc705_Schematic.pdf

I have problems with U55, address 52. The fault signal FTL happen and then there are no output on PTD08A010 because the SRE-4A signal on pin 33 is always down.

I try to follow the suggestion on this post: 

http://e2e.ti.com/support/power_management/digital_power/f/184/p/114400/415673.aspx#415673

by Mark Hagen : "Unfortunately, the FLT indication from the driver/power module does not have a corresponding fault response command.  So the recovery must be handled by the host by either sending an OPERATION command to turn off, then on, or by cycling the PMBus CTRL signal."

But still the problem continue.

I appreciate to much your help to solve this issue.

Best,

Marcelo

  • 0
    TI__Genius 13700 points

    The FLT signal from the PTD module originates from the UCD7230 driver on the board.  The UCD7230 raises the FLT line under two conditions, High Side Mosfet Over Current as set by the CS+ pin or when the Average Output Current exceeds the limit set by ILIM pin, both these pins are on the UCD7230 not the PTD module.

    Can you get a screen shot from an oscilliscope of the PTD module's output at start-up?

    Is the output shorted?

  • 0 in reply to Brad
    Prodigy 20 points

    Hi Brad, I remove the PTD form the board and when I measure between pin 1 and 4 it is Ok.

    The weird thing is that on the board is look like a short. I have another PTD on the same board that look like it was in short but when I power up is working fine.

    That is way I cannot understand where the problem came form, if there are a real short on the board or there is a problem on the PTD.

    If you have time please take a lock on schematics page 45 the one that works ok and page 39 the one that fail, both has exactly the same configuration.

    I appreciate to much your help.

    Best,