Power Considerations for XEM3010

Spartan-3 USB 2.0 Modules
1

I am currently designing a characterization board using the XEM3010 and have some questions about the actual connector and power settings.

  • Just confirming that Option 2 seems to suggest I could use my on-board 5v supply to power the board, which is what I intend to do.
  • If I use my own on-board power to drive the OpalKelly, my assumption would be that I would NOT need to supply voltages to the 3.3VDD and 1.2VDD connector unless I removed the switching regulators (Option 4). In fact, it seems that doing so could potentially damage the board by attaching my own 3.3V or 1.2V supplies, is this correct?
  • Additionally, it seems connecting my PCB DGND to the OpalKelly’s DGND could potentially create ground current loops (My instruments’ GND path vs. Laptop’s USB). Are there some special design considerations on my PCB, or Alterations to the Opal Kelly (0-ohms) that i would need to make to ensure a clean ground path?
  • Lastly, If i were to use 3.3V and 1.2V on the OpalKelly for my devices, what kind of load current can be supplied? Or are these voltages meant to be used as references for a buffer?
2

  1. Yes, you may.

  2. (a) Yes, regulators are on the XEM3010. (b) Of course, it’s generally a bad idea to have two power supplies contend.

  3. This has generally not been a problem for customers as far as we know.

  4. This is mostly dependent on your FPGA design and it’s power requirements. The XEM3010 consumes around 100 - 150mA on the 3.3v supply during normal operation. FPGA and SDRAM power requirements are not included in that number and need to be determined by the end-user.