Jetson Carrier Design

flux

Parts are selected: FE1.1s hub, CP2108 for UART1-4, CP2105 for UART5-6, 12 MHz crystal, 12 V input protection, 5 V/3.3 V bucks, USB-B upstream, Jetson power, and six UART headers. I’m adding the schematic blocks now.

flux

Started the schematic and renamed the project to “Jetson CP2108 UART Carrier.” I added the CP2108 + CP2105 six-UART architecture, USB-B upstream connector, FE1.1s USB hub, 12 V input, 5 V/3.3 V regulators, Jetson power connector, six UART headers, key decoupling/support passives, USB nets, and updated the Project Specification.
Open items:
  • I was blocked before running the final ERC/connectivity review because the account has no available ACUs.
  • MP2329 5 V buck feedback values and final high-current inductor/fuse MPN still need confirmation.
  • Some schematic wire/label collision warnings likely remain and need cleanup.
  • Sensor headers are currently assumed 3.3 V UART logic.
Suggested next steps:
  1. Add ACUs, then ask me to “run ERC and clean up the schematic.”
  2. Confirm whether all six sensor headers should be 3.3 V, 5 V, or mixed.
  3. Finalize the MP2329 power-stage values and protection parts.
  4. Then proceed to 4-layer layout setup for USB 2.0 controlled-impedance routing.
Run ERC cleanup
Use 3.3 V UART
Finalize power stage
Finalize and clean

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Project Specification
Project Overview
Status: Draft schematic started.
This project is a Jetson Orin NX/J4012 companion carrier/interface board. It accepts a nominal 12 V DC input, generates 5 V and 3.3 V rails, and exposes multiple UART sensor ports to the Jetson over USB.
The USB-UART architecture is being simplified from six individual CP2102N bridges to a multi-UART architecture. Because CP2108 is a quad-channel USB-UART, the six-port target requires either CP2108 + a dual USB-UART bridge, or two CP2108 devices with two spare UARTs.
Intended Use
Prototype carrier/interface board for connecting UART-based sensors such as lidar/rangefinder, GPS, compass, and additional serial sensors to a Jetson host.
What the Device Should Do
  • Accept a 12 V DC input.
  • Generate a high-current 5 V rail for Jetson-side power and 5 V peripherals.
  • Generate a 3.3 V rail for USB-UART logic and 3.3 V sensors.
  • Connect up to six UART sensor ports to the Jetson through one USB upstream cable.
  • Provide ESD/protection on exposed power and USB interfaces.
Main Features
  • 12 V input power protection.
  • 5 V buck regulator sized around the Jetson + sensor load.
  • 3.3 V regulator for logic/sensor rail.
  • CP2108 quad USB-UART bridge for UART channels 1-4.
  • Additional dual USB-UART bridge or second multi-UART bridge for UART channels 5-6.
  • USB 2.0 upstream connector to Jetson.
  • Sensor headers with VCC, GND, TX, RX.
System Architecture
Diagram



  
    
  
  
    
  





























12 V DC Input
Fuse + TVS + reverse protection
5 V Buck Regulator
5 V Rail
Jetson 5 V / VDD_IN connection
3.3 V Regulator
3.3 V Rail
USB upstream to Jetson
USB 2.0 Hub
CP2108 Quad USB-UART
Dual USB-UART for UART5-6
UART Sensor Headers 1-4
UART Sensor Headers 5-6
5 V sensor supply where needed
3.3 V sensor supply where needed
Hardware Subsystems
Power
  • Nominal 12 V input.
  • Protected by input fuse and TVS diode.
  • 5 V synchronous buck regulator sized for Jetson and downstream loads.
  • 3.3 V regulator sized for USB-UART ICs and 3.3 V sensors.
USB/UART
  • USB 2.0 upstream connection to Jetson.
  • Small self-powered USB hub if more than one USB-UART bridge is used.
  • CP2108 handles four UART channels.
  • Remaining two UART channels require a dual USB-UART bridge or second multi-UART bridge.
Sensor Connectors
  • Six 4-pin UART headers: VCC, GND, sensor TX, sensor RX.
  • UART logic is assumed 3.3 V unless a specific sensor requires level shifting.
Interfaces and Connections
  • 12 V DC input connector.
  • Jetson 5 V power output/connection.
  • USB 2.0 upstream data connection to Jetson.
  • Six UART sensor headers.
  • Optional test points for VIN, 5V, 3V3, GND, USB D+/D-, and UART TX/RX.
Power and Runtime Expectations
  • Externally powered from 12 V adapter or system power bus.
  • No battery/runtime target in this revision.
  • 5 V rail must tolerate Jetson high-performance load plus USB/sensor load.
Power Tree and Power Budget
Initial sizing budget:

Table

RailLoadEstimated Current
5 VJetson Orin NX/J4012 load allowance5.0 A peak
5 VUSB hub + USB-UART bridge inputs~0.2-0.5 A
5 V5 V sensors~0.1-0.3 A
3.3 VUSB-UART logic and 3.3 V sensors~0.1-0.3 A
Initial 5 V regulator target: at least 6 A output, with thermal review required during layout.
Manufacturing and Assembly Expectations
  • 4-layer PCB recommended for USB 2.0 differential routing and power integrity.
  • SMD assembly expected due to QFN USB-UART and regulator parts.
  • Use real, sourced library parts with datasheets for all active ICs.
Firmware-Relevant Hardware Requirements
  • Jetson should enumerate the USB-UART bridges as serial devices.
  • Stable USB device identity/port mapping should be documented later.
  • Sensor UART voltage levels must match the bridge-side I/O voltage or be level shifted.
Physical Design Expectations
  • Board size and connector locations are not yet specified.
  • USB differential pairs should be short, length-matched, and referenced to solid ground.
  • High-current 5 V path needs wide copper and thermal consideration.
Important Design Decisions
  • Use CP2108 for four UART channels instead of four separate CP2102N devices.
  • Preserve the six-UART requirement by adding either a dual USB-UART device or another multi-UART device.
  • Prefer 4-layer stackup for USB 2.0 and current-carrying power rails.
Assumptions
  • 12 V nominal input.
  • Six UART sensors are still required.
  • UART logic levels are 3.3 V unless a sensor datasheet says otherwise.
  • The Jetson connection method is USB upstream plus 5 V power connection, not a full custom SO-DIMM carrier yet.
Change Notes
  • Initial specification created from the uploaded architecture.
  • Architecture updated from six CP2102N bridges to CP2108-based multi-UART approach.

  • Project Overview

  • Intended Use

  • What the Device Should Do

  • Main Features

  • System Architecture

  • Hardware Subsystems

  • Power

  • USB/UART

  • Sensor Connectors

  • Interfaces and Connections

  • Power and Runtime Expectations

  • Power Tree and Power Budget

  • Manufacturing and Assembly Expectations

  • Firmware-Relevant Hardware Requirements

  • Physical Design Expectations

  • Important Design Decisions

  • Assumptions

  • Change Notes

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Jetson CP2108 UART Carrier 7272

Jetson CP2108 UART Carrier 7272 thumbnail
Jetson Orin NX/J4012 carrier concept with 12 V input power, 5 V and 3.3 V rails, USB 2.0 upstream connection, and a CP2108 multi-UART USB bridge for up to six UART sensor headers.

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