Power consumption (SBC Lynx)

Info Box Applies to SBC Lynx

Introduction

Providing theoretical power consumption values would be useless for the majority of system designers building their application upon SBC Lynx board. Practically speaking, these figures would be of no help when it comes to size power supply unit or to perform thermal design of real systems. Instead, several configurations have been tested in order to provide figures that are measured on real-world use cases.

Please note that SBC Lynx platform is extremely flexible, so it is virtually impossible to test for all possible configurations and applications on the market. The use cases here presented should cover most of real-world scenarios. However actual customer's application might require more power than values reported here or customer's use case may be differ significantly with respect to the ones here considered. Therefore, application-specific requirements have always to be taken into consideration in order to size power supply unit and to implement thermal management properly.

Heavy load configurations

Measurements have been performed on the following platform:

• SBC Lynx rev.0 (S-XUBB0000C0R) equipped with a plug-in board for 24-bit RGB LCD interfacing
  • LCD p/n: KOE TX11D06vm2Apa (https://www.koe-europe.com/doc/TX11D06VM2APA.pdf)
• System software: XUELK 0.9.0, patched to include 24-bit RGB LCD support
• Power monitor: a custom current probe has been connected to the input power rail at 12V.

Use cases results

The following table shows the summary result of data collected at different checkpoints:

Checkpoint	Power [mW]
U-Boot prompt	854
Linux prompt [1]	1000
StressAppTest	1200
StressAppTest + LCD	2220
Complete Stress Test + LCD	2880

[1] In this configuration, Linux kernel spends most of the time in idle state because user space applications and interrupt service routines run for very short periods. However, LCD is turned on (LCD power consumption is about 600mA).

Additional notes and reference:

• U-boot is set to work at 396MHz
• At Linux prompt, a fixed clock frequency of 528MHz has been set (userspace governor)
• All the measures include Ethernet link at 100M
• StressAppTest application is used to stress CPU and DDR3 RAM (https://github.com/stressapptest/stressapptest)
• An 4.3 inches 480x272 pix LCD is used to test the 24bit parallel video interface output. The LCD backlight is driven by the 12V VIN using an external circuitry at 100% brightness
• Complete Stress Test includes the following tests:
  • StressAppTest
  • USB Host: read/write/verify on an USB stick
  • USB otg tested as Host: read/write/verify on an USB stick
  • uSD card: read/write/verify
  • ETH: iperf TCP test at 100M
  • NAND: stress test with mtd kernel modules

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