High Power Consumption of RTC in Jetson Orin Nano

Issue Overview

The Jetson Orin Nano module exhibits a relatively high power consumption for its Real-Time Clock (RTC) during battery backup operation. According to the Jetson Orin Nano Series Modules Data Sheet (DS-11105-001_v1.2.pdf), the power consumption on the PMIC_BBAT pin ranges from 12 to 50µA. This high power draw significantly impacts the battery life of devices using the Jetson Orin Nano, particularly those relying on small batteries like the CR2450 for RTC backup.

In the worst-case scenario of 50µA consumption, calculations suggest that a standard CR2450 battery (500mAh capacity) would last only slightly over a year. This power consumption is notably higher than typical standalone RTC chips, which usually consume around 1µA.

Possible Causes

1. Design Choice: The high power consumption may be a deliberate design decision by NVIDIA to support additional features or maintain system stability.

2. Additional Components: The PMIC_BBAT pin might be powering more than just the RTC, leading to increased power draw.

3. Hardware Limitations: The specific RTC hardware used in the Jetson Orin Nano module may have inherently higher power requirements compared to standalone RTC chips.

4. Power Management Inefficiencies: There could be inefficiencies in the power management system of the Jetson Orin Nano module, resulting in higher than necessary power consumption for the RTC function.

Troubleshooting Steps, Solutions & Fixes

1. Confirm Power Consumption:

   • Measure the actual power consumption of your specific Jetson Orin Nano module to verify if it matches the datasheet specifications.
   • Use a high-precision multimeter to measure the current draw on the PMIC_BBAT pin during battery backup operation.

2. Consider External RTC:

   • Implement an external RTC with lower power consumption as an alternative to the built-in RTC.
   • Select a low-power RTC chip that consumes around 1µA or less.
   • Integrate the external RTC into your design, ensuring proper communication with the Jetson Orin Nano module.

3. Disable Internal RTC Battery Backup:

   • If using an external RTC, consider not connecting a battery to the PMIC_BBAT pin of the Jetson Orin Nano module.
   • Verify that this doesn’t affect any other functions of the module. (Note: The Developer Kit doesn’t use a battery, suggesting this approach may be viable).

4. Optimize Power Management:

   • Investigate if there are any software-level optimizations that can reduce power consumption during battery backup mode.
   • Check for any available firmware updates from NVIDIA that might address power consumption issues.

5. Use Larger Capacity Battery:

   • If the internal RTC must be used, consider using a larger capacity battery to extend the backup time.
   • Calculate the required battery capacity based on your specific use case and desired backup duration.

6. Consult NVIDIA Support:

   • Reach out to NVIDIA developer support for any potential workarounds or upcoming solutions to reduce RTC power consumption.
   • Inquire about the possibility of future hardware revisions that might address this issue.

7. Design Considerations:

   • If developing a product, consider implementing a user-replaceable battery design to facilitate easy battery changes.
   • Implement a low-battery warning system to alert users when the RTC backup battery needs replacement.

It’s worth highlighting that according to an NVIDIA representative, the power consumption of the RTC cannot be adjusted and remains at 50µA in the worst case. Therefore, for applications requiring lower power consumption, implementing an external RTC appears to be the most viable solution at present.