PCIe RESET_N, CLKREQ, WAKE_N voltage level at M.2 M and E key

Autonomous Machines Jetson & Embedded Systems Jetson AGX Xavier
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1

Hi,

Xavier OEM says PCIe RESET_N, CLKREQ, and WAKE_N signals are “CMOS – 1.8V”.
I also read through Xavier devkit schematic. I can see that they are directly connected to M.2 M key and M.2 E key connectors WITHOUT going through any voltage level shifter.

  1. Should these signals converted from 1.8V to 3.3V using level shifter, and then connected to M.2 M/E key?
  2. What’s the PCIe standard requirement on voltage level of these pins?
  3. Is the expected voltage level dependent on the device connected on M.2 M/E key? (e.g. NVMe SSD, or wifi chip) I highly doubt that it is device dependent, because it should follow a “universal” standard.

Regards.

3

Please check the OEM DG. There are 3.3V pull-up in module for these pins.

4

Hi,

I don’t see OEM says they are 3.3V pull-up in module. Can you check my attached screenshot?

PCIe_pins
PCIe_pins1853×1053 224 KB

5

In figure 7-4 PCIe Root Port Connection Example

6

I see. Thanks so much.

I highly recommend NVIDIA document it in the pin descriptions in proper words, other than put it in figure.

Regards.