Chapter 13. Pads; Internal Pull-Ups For Dual Voltage Block Pins Power At 1.8V; Schmitt Trigger Usage - Nvidia Jetson Xavier NX Design Manual

Chapter 13. PADS

Jetson Xavier NX signals that come from the SoC may glitch when the associated power rail is
enabled. This may affect pins that are used as GPIO outputs. Designers should take this into
account. GPIO outputs that must maintain a low state even while the power rail is being
ramped up may require special handling.
13.1 Internal Pull-ups for Dual Voltage
Block Pins Power at 1.8V
Several of the MPIO pads are on blocks designed to be powered at either 1.8V or 3.3V. These
blocks are powered at 1.8V on Jetson Xavier NX, and the internal pull-up at initial Power-ON is
not effective. The signal may only be pulled up a fraction of the 1.8V rail. Once the system
boots, software can configure the pins for 1.8V operation and the internal pull-ups will work
correctly. If these signals need the pull-ups during Power-ON, external pull-up resistors
should be added. The following pins listed are the affected pins. These are the Jetson Xavier
NX pins on the dual voltage blocks powered at 1.8V with Power-ON reset default of Internal
pull-up enabled.
SDMMC_DAT0

SDMMC_DAT1

SDMMC_DAT2

SDMMC_DAT3

SDMMC_CMD

SPI1_CS0*

SPI1_CS1*

13.2

Schmitt Trigger Usage

The MPIO pins have an option to enable or disable Schmitt-trigger mode on a per-pin basis.
This mode is recommended for pins used for edge-sensitive functions such as input clocks, or
other functions where each edge detected will affect the operation of a device. Schmitt-trigger
mode provides better noise immunity and can help avoid extra edges from being "seen" by the
Xavier inputs. Input clocks include the I2S and SPI clocks (
NVIDIA Jetson Xavier NX
and
I2Sx_SCLK SPIx_SCK
DG-09693-001_v1.7 | 78
) when Xavier