Usb Superspeed Hub; Power Over Ethernet; Ti Txb0108 Level Shifters; Features Not To Be Implemented - Nvidia Jetson Orin NX Series Product Manual

4.2

USB SuperSpeed Hub

The USB 3.2 hub design uses a Realtek RTS5420 device. The hub circuit includes a SPI FLASH
device which holds configuration information. A design intending to duplicate the reference
design hub implementation should include the same SPI FLASH programmed to match, or the
hub should be customized with fuses with the same settings. The configuration in the SPI
FLASH includes the following:
Power enables (DPS1/2/3/4_PWR) set to be active high

Charging feature disabled

SSC valid

4.3

Power over Ethernet

The reference design includes a 4-pin Power over Ethernet (PoE) header (J19) which brings
out the VC power pins of the Ethernet connector. To use this alternate PoE power mechanism
to power a custom carrier board, the design would require a PoE PD controller or converter to
take the high voltage PoE supply (38V-60V) and convert it to the correct voltage for the custom
carrier board. The output of the PoE converter would be supplied where the DC Jack power
comes in on the NVIDIA Orin Nano DevKit. The DevKit has an optional PoE Backpower jumper
(J18) for this purpose.
4.4

TI TXB0108 Level Shifters

The reference design uses these level shifters to shift many of the signals going to the 40-pin
header from 1.8V to 3.3V. The design of these level shifters supports bidirectional signaling
without the use of a direction signal but has some side effects that should be considered. See
Jetson Nano Developer Kit 40-Pin Expansion Header GPIO Usage Considerations
the
Applications Note
for details.
4.5

Features Not to Be Implemented

The reference design features that should not be copied as they are not required or useful for
a custom carrier board design. The ID EEPROM (U17) is a feature that is used for NVIDIA
internal purposes, but not recommended on a custom design. If a similar functionality is
PRELIMINARY INFORMATION
Jetson Orin NX Series and Jetson Orin Nano Series
Developer Kit Feature Considerations
terface.
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