Not allowed to limit reverse current on carrier board?

Issue Overview

Users have raised concerns regarding the design guidelines for the Nvidia Jetson Orin Nano and Orin NX, specifically about the note in the design guide stating that any eFUSE or current limiting device on the input power rail should not limit reverse current. The main symptoms reported include confusion over the implications of this guideline and potential issues that may arise if reverse current protection is implemented.

This issue typically occurs during the design phase of projects involving the Jetson Orin Nano, particularly when users are integrating power supply circuits. Users have expressed uncertainty about how to handle sudden current fluctuations that may occur during operation, especially under heavy load conditions.

The context of these discussions highlights concerns about hardware specifications, particularly the power supply circuit’s ability to manage dynamic load variations without triggering reverse voltage protection mechanisms. This issue appears to be consistently raised by multiple users, indicating a broader concern among developers working with this platform. The impact of misunderstanding this guideline could lead to improper circuit designs, potentially resulting in system instability or failure.

Possible Causes

• Hardware Incompatibilities or Defects: If a current limiting device is incorrectly selected, it may not accommodate the rapid fluctuations in current demand, leading to system errors.

• Software Bugs or Conflicts: While less likely, software configurations that interact with hardware power management could potentially exacerbate issues related to current handling.

• Configuration Errors: Users may misinterpret the design guidelines or fail to account for specific load conditions, leading to improper circuit designs.

• Driver Issues: Although primarily a hardware issue, outdated or incompatible drivers could potentially affect power management features.

• Environmental Factors: Variations in temperature or power supply quality could influence how well the system handles current fluctuations.

• User Errors or Misconfigurations: Misunderstanding the guidelines could lead users to implement unnecessary reverse current protection, which could interfere with normal operations.

Troubleshooting Steps, Solutions & Fixes

1. Review Design Guidelines:

   • Carefully read through the Nvidia Jetson Orin Nano design guide, focusing on the sections related to power management and current limitations.
   • Pay special attention to page 18 (or 29 in PDF format) where the note regarding reverse current is specified.

2. Analyze Current Load Requirements:

   • Assess your application’s load requirements to understand how dynamic changes in CPU and GPU loads might affect current consumption.
   • Use a multimeter or oscilloscope to monitor real-time current fluctuations during operation.

3. Select Appropriate Power Supply Components:

   • Choose eFUSE or current limiting devices that are rated for high transient currents and do not limit reverse current.
   • Consult with suppliers for components specifically designed for applications with high dynamic load variations.

4. Test Different Configurations:

   • If possible, prototype different power supply configurations without reverse current limiting to observe system behavior under load.
   • Compare results from configurations with and without reverse current protection.

5. Monitor System Behavior:

   • Implement logging for power consumption metrics during application execution to identify patterns or anomalies associated with load changes.
   • Document any failures or unexpected behaviors for further analysis.

6. Consult Community and Documentation:

   • Engage with community forums for additional insights from other developers who may have faced similar issues.
   • Refer to Nvidia’s official documentation for updates on best practices regarding power management in Jetson modules.

7. Future Prevention Best Practices:

   • Keep abreast of updates from Nvidia regarding design guidelines and best practices.
   • Regularly review your design against updated documentation before finalizing hardware configurations.

8. Unresolved Aspects:

   • Further investigation may be needed into specific failure modes that could arise from ignoring the reverse current limitation guideline.
   • It may also be beneficial for Nvidia to clarify this note in future revisions of their design guide based on user feedback.

By following these steps and recommendations, users can better navigate the challenges associated with implementing power supply circuits for the Nvidia Jetson Orin Nano and ensure robust system performance.