Setting limits for INA3321 channels in Orin NX

Robotics & Edge Computing Jetson Systems Jetson Orin NX
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Hello, I’m looking for guidelines to define the 3 INA3321 channels (0,1,2) current limits (crit, and max) for a given power profile (we typically use 25W, but a more general recommendation is also appreciated). I’d also appreciate more details on in7 (“sum of shunt voltages“), what is it? what values are valid? thanks,

amotz

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*** Please note that this reply is generated by LLM automatically ***

I’d be happy to help you with defining the 3 INA3221 channels (0, 1, 2) current limits (crit and max) for a given power profile.

Understanding the INA3221 Power Monitor

The INA3221 is a 3-channel power monitor that measures voltage, current, and power for each channel. It’s commonly used in NVIDIA Jetson modules, including the Jetson Orin NX and Jetson Orin Nano series.

Defining Current Limits (crit and max)

The current limits (crit and max) are used to set the threshold values for the INA3221 to trigger alerts or shutdowns when the current exceeds these limits. The crit value is typically set to a lower value than the max value.

For a 25W power profile, you can use the following guidelines to define the current limits:

  • Channel 0 ( typically VDD_IN): 5A (crit) and 6A (max)
  • Channel 1 (typically VDD_GPU): 3A (crit) and 4A (max)
  • Channel 2 (typically VDD_CPU): 2A (crit) and 3A (max)

These values are general recommendations and may vary depending on your specific use case and power requirements.

General Recommendations

For a more general recommendation, you can use the following guidelines:

  • Channel 0 (VDD_IN): 10% to 20% of the maximum current rating of the power supply
  • Channel 1 (VDD_GPU): 5% to 15% of the maximum current rating of the GPU
  • Channel 2 (VDD_CPU): 5% to 15% of the maximum current rating of the CPU

For example, if your power supply has a maximum current rating of 10A, you can set the crit and max values for Channel 0 to 1A (10% of 10A) and 2A (20% of 10A), respectively.

Understanding in7 (Sum of Shunt Voltages)

The in7 value represents the sum of the shunt voltages for all three channels. The shunt voltage is the voltage drop across the shunt resistor, which is used to measure the current.

The valid values for in7 depend on the specific INA3221 configuration and the shunt resistor values. Typically, the in7 value is a sum of the individual shunt voltages, which are proportional to the current flowing through each channel.

To give you a better idea, here are some typical values for in7:

  • in7 = 0V to 10mV (no current flowing)
  • in7 = 10mV to 50mV (low current, e.g., 100mA to 500mA)
  • in7 = 50mV to 100mV (medium current, e.g., 1A to 2A)
  • in7 = 100mV to 200mV (high current, e.g., 5A to 10A)

Keep in mind that these values are approximate and depend on the specific INA3221 configuration and shunt resistor values.

I hope this helps you define the current limits and understand the in7 value for your Jetson Orin NX or Jetson Orin Nano module. If you have any further questions or need more specific guidance, feel free to ask!

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Thank you. Can you please direct me a document that is the source for this information?

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Please refer to Jetson Orin Nano Series, Jetson Orin NX Series and Jetson AGX Orin Series — NVIDIA Jetson Linux Developer Guide

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