Developer Kit Feature Considerations
PRELIMINARY INFORMATION
NVIDIA Jetson Orin NX DG-10931-001_v0.1 | 10
4.2 USB SuperSpeed Hub
The USB SS 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.
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
the
Jetson Nano Developer Kit 40-Pin Expansion Header GPIO Usage Considerations
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 (P3509 - U17) is a feature that is used for
NVIDIA internal purposes, but not recommended on a custom design. If a similar functionality
is desired for a custom design, avoid using address 7’h57 on the I2C2 interface.
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