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.

The following picture shows a simplified block diagram of the measurement system.

Simplified block diagram of the measurement system

Heavy load configurations

Measurements have been performed on the following platform (also denoted as testbed1 in the rest of the document):

• 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
• processor's LDO is enabled

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

Checkpoint	Board power consumption (probe #1) [mW]	Processor subsystem power consumption (probe #2) [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)
• A 4.3 inches 480x272 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

Idle configurations

Some power-constrained applications can't afford to make use of deep-sleep mode because wake up process takes too long to complete. In such situations aggressive implementation of so-called idle mode can come to help. Basic assumption is that the system spends most of the time in a system idle condition, that is there are no user applications ready to run nor interrupt requests to serve.

Measurements have been performed on the following platform (also denoted as testbed2 in the rest of the document):

• SBC Lynx rev.0 (S-XUBB0000C0R) equipped with a plug-in board for 24-bit RGB LCD interfacing
• System software: XUELK 0.9.0
• processor's LDO is enabled
• TBD elencare modifiche hw (phy can ecc.)
• Power monitors: two custom current probes have been used
  • power probe #1 is connected to the input power rail at 12V
  • power probe #2 is connected to the input power rail of the PMIC NXP PF3000; this, in turn, powers NXP iMX6UL processor, DDR3L SDRAM, Flash memories, Ethernet PHY, TBD

Two idle configurations have been tested, detailed in the following sections. Nomenclature is the same used in the processor's data sheet.

Please note that the consumption measured by power probe #2 takes into account PMIC PF3000 too. TBD

System idle

In this case the default interactive governor is used.

Board power consumption (probe #1) [1],[2] [mW]	Processor subsystem power consumption (probe #2) [1],[2] [mW]
TBD [2]	TBD [2]

[1] Processor subsystem includes:

• iMX6UL processor
• DDRL SDRAM
• TBD

[1] Power consumption of the following parts is excluded:

• CAN PHY
• RS485 polarization network
• TBD

[2] 24MHz active oscillator power consumption is included. As the board under test is equipped with iMX6UL revision 1.0, active oscillator is required to implement the fix described by errata ERR009455. For more details please refer to Chip Errata for the i.MX 6UltraLite. Future revision of the board will be populated with silicon revision 1.1 or newer. Thus active oscillator will be removed.

Low-power idle

In this case the powersave governor is used. As described in i.MX 6UltraLite Power Consumption Measurement application note, the use of this governor allows to reduce power consumption significantly in idle condition.

Board power consumption (probe #1) [1],[2] [mW]	Processor subsystem power consumption (probe #2) [1],[2] [mW]
TBD	TBD

[1] Power consumption of the following parts is excluded:

• CAN PHY
• RS485 polarization network
• TBD

[2] 24MHz active oscillator power consumption is included. As the board under test is equipped with iMX6UL revision 1.0, active oscillator is required to implement the fix described by errata ERR009455. For more details please refer to Chip Errata for the i.MX 6UltraLite. Future revision of the board will be populated with silicon revision 1.1 or newer. Thus active oscillator will be removed.

Deep-sleep mode (aka suspend)

TBD

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