Radxa X4 Power Input and Consumption Measurements

I recently conducted a series of power-related measurements on the Radxa X4, aiming to understand its input requirements and consumption characteristics. The board was tested without an operating system and with no peripherals connected, except for antennas, booting directly into the BIOS.

Power Input Observations:

The Radxa X4 supports power input through USB Type-C PD Version 2.0 at 12V/2.5A. Additionally, it can be powered via a PoE HAT. It’s important to note that powering the board through the 2x20 GPIO header is not recommended. The schematic indicates that these pins have a series diode, making them suitable only for output. Furthermore, the 5V, 3.3V, and 1.8V regulators derive their input from the 12V main supply.

Voltage Behavior:

During testing, the board did not power on with a 5V input. However, it successfully powered on with both 9V and 12V inputs.

Current Consumption Measurements:

Using an Analog Discovery 2, I measured the voltage across a 150mΩ shunt resistor in a 12V configuration (PC power supply → X4 → Shunt → GND). The measurements were as follows:

  • Booting, pre-BIOS: Peak of 200mV across the shunt, corresponding to approximately 1.33A at 11V, resulting in a power consumption of about 14.67W.
  • While in BIOS: Peak of 300mV across the shunt, corresponding to approximately 2A at 11V, resulting in a power consumption of about 22W.
  • Average during booting and in BIOS: 175mV across the shunt, corresponding to approximately 1.167A at 11V, resulting in a power consumption of about 12.84W.

Attached are the waveform images and corresponding files compatible with WaveForms software for detailed analysis (link to gDrive)

Additional Observations:

The BIOS appears to consume more power compared to running an operating system. For instance, running Ubuntu from a USB drive showed more efficient power consumption, indicating that the BIOS may have higher power demands.

I hope these insights are helpful to the community. If anyone has further observations or recommendations regarding the Radxa X4’s power consumption, please share them.


Edit:

The X4 used in this test is an SBC with 4GB of RAM and no eMMC.

A monitor was connected via HDMI during the measurement.

Timing details:

  • Initially, everything is off.
  • The power supply is turned on.
  • At -0.700 min , the BIOS starts loading (an HDMI image is displayed).
  • From -0.600 min , the BIOS screen remains active.
  • At -0.170 min , the SBC is shut down using its power button.
  • The final voltage drop corresponds to turning off the power supply.
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Nice but without any info about the power-related UEFI settings (power limits, C-states) these numbers don’t mean much.

Thank you for your observation. During the tests, all BIOS settings were left at their default configurations. Specifically, C-states were disabled, as were PL1, PL2, and the overrides for PL3 and PL4. If there are other relevant settings to these measurements, please let me know.

C states should be always enabled. Disabling them makes the board less efficient and less speedy.

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Thank you for your feedback. I will re-enable the C-states and repeat the measurements to obtain more accurate data.

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