UVLO on BBAT Pin?

Issue Overview

The discussion revolves around concerns regarding the BBAT pin on the Nvidia Jetson Orin Nano Dev board, specifically related to the voltage levels at which the Power Management Integrated Circuit (PMIC) operates. Users are experiencing uncertainty about:

• Symptoms: Users are questioning how deeply a rechargeable cell can be discharged when connected to the BBAT pin and the minimum voltage at which the PMIC will cease to draw power.

• Context: The issue arises during the evaluation of battery life and performance of designs using rechargeable cells. Users are particularly interested in understanding the implications of discharging cells to 1.85V, as this is identified as the minimum operational voltage for the PMIC.

• Hardware/Software Specifications: The relevant hardware is the Jetson Orin Nano Dev board, and discussions reference specifications from the module data sheet regarding voltage levels.

• Frequency: The issue appears to be a common concern among users, indicating a need for clarity on battery management.

• Impact: Misunderstanding these voltage levels can lead to premature battery failure or inadequate performance in applications relying on rechargeable cells.

Possible Causes

Several potential causes for this issue have been identified:

• Hardware Incompatibilities or Defects: If the PMIC does not function as specified at low voltages, it could lead to unexpected power management issues.

• Software Bugs or Conflicts: Firmware managing battery operations may not properly account for low voltage scenarios, leading to incorrect behavior.

• Configuration Errors: Incorrect setup or wiring of the battery management system could result in improper voltage readings or management.

• Driver Issues: Outdated or incompatible drivers could affect how the system interacts with power management features.

• Environmental Factors: Variations in temperature or power supply quality could influence battery performance and PMIC operation.

• User Errors or Misconfigurations: Users may not fully understand how to configure their systems for optimal battery performance, leading to unexpected discharges.

Troubleshooting Steps, Solutions & Fixes

To address concerns regarding the BBAT pin and its operational limits, follow these troubleshooting steps:

1. Verify Voltage Levels:

   • Use a multimeter to measure the voltage at the BBAT pin while connected to a rechargeable cell.
   • Ensure that it remains within the specified range of 1.85V to 5.5V as per the module data sheet.

2. Check PMIC Operation:

   • Confirm that below 1.85V, no current is drawn from VBAT by observing power consumption with an ammeter.
   • Note that once voltage dips below 1.85V, PMIC RTC will not operate, halting current draw.

3. Monitor Leakage Current:

   • While there is no precise estimate provided in the discussion, typical leakage current at low voltages is reported to be around 12µA.
   • Measure this current if possible to assess battery drain during low-voltage conditions.

4. Test Different Battery Types:

   • Experiment with different rechargeable cells to determine if performance varies significantly below 1.85V.
   • Ensure that any cell used can maintain output at this minimum voltage level.

5. Update Firmware and Drivers:

   • Check for any available firmware updates for the Jetson Orin Nano that may address power management issues.
   • Install any recommended driver updates that could improve compatibility with battery management systems.

6. Consult Documentation:

   • Refer to the Jetson Orin Nano Series Module Data Sheet for detailed specifications about BBAT pin operations and PMIC behavior.
   • Look for any application notes or technical documents that provide additional guidance on managing battery health and performance.

7. Best Practices for Battery Management:

   • Avoid discharging batteries below recommended levels (ideally above 3.0V) to prolong lifespan.
   • Implement monitoring systems that alert users when voltage approaches critical thresholds (e.g., below 3.0V).

8. Future Investigations:

   • Users should continue discussions in forums or contact Nvidia support for further clarification on leakage current and PMIC behavior below specified thresholds.
   • Engage with other users who have successfully navigated similar issues for shared insights and solutions.

By following these steps, users can better understand and manage their experiences with the Nvidia Jetson Orin Nano Dev board’s BBAT pin functionality and ensure optimal operation of their devices.