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UCD9248: UCD9248

Nishitha Ravichandran
Prodigy 80 points
Part Number: UCD9248
Other Parts Discussed in Thread: PTD08D210W

Good day!

In the power section of the ZC702 eval board from Xilinx, power section uses UCD9248. The datasheet of the evaluation kit has been attached to this thread.

1) What are the fault B lines for (Refer pages 39, 42 and 45)? The netlabels (eg. PWRCTL_VCC2B_FLT) are connected to other UCD9248s. We understood what the A channel fault lines do (fault detection from PTD08D210W), but couldn't understand B channel's fault line functionality.

2) What is the SEQ IOs for?

Our basic idea is that these are for sequencing. But from UCD's datasheet http://www.ti.com/lit/ds/symlink/ucd9248.pdf (page 26- Sequencing), there are three methods of sequencing. In that case,

a) Does the ZC702 board have the option of sequencing in all three methods?

b) Which sequencing is better? Can we connect only those lines and leave the remaining floating?

3) We found that on page 42, the CS lines are short to AGND2 which is not connected system ground (GND or AGND2_9248). Is this correct? If yes, could you please justify?

4) On page 45, the CS lines are again connected to AGND2 which is again confusing. Is this also correct?

We request you to clarify these doubts as soon as possible.

Thanks and regards,

Nishitha and teamxtp185-zc702-schematic-rev1-1.pdf

  • 0
    TI__Intellectual 925 points
    Hi Nishitha,
    Here are some thoughts:
    1) Looks like it’s the power good (PGOOD) signal from U22 (see pg.37). I suspect that the UCD9248 devices are programmed to turn off if there is a fault from U22.
    2) I’m not sure if I understand this question: The power sequencing is application specific. In this case it is dictated by the start-up requirements of the Zynq-7000 SoC. The UCD9248's in your system will have the SEQ pins' functions set in various ways so as to meet those requirements. You will have to refer to Xilinx’s documentation.
    3) That does seem strange. I would expect it to be tied to AGND2_9248. We separate the grounds to minimize noise, but all these should ultimately be connected to the system ground.
    4) I would expect this to be connected to AGND3_9248. Looks like a simple oversight. Note how the grounds are connected on the UCD9248 on pg.39.
    All the best!