Power Supply and Heat Dissipation¶

Customers using the MitySOM-QC6490 SOM must be conscious of both the power supply requirements and the thermal management solution of their final design.

Test Measurements¶

Temperature and Power Data has been collected under a few different scenarios. See below for recreating scenarios.

Temperature for the CPU, GPU, PMICs (PM7325, PM7250B), and DDR dies were captured using the onboard QC6490 temperature sensors via sysfs access. Temperature measurements for the QC6490 SoC package and the ambient SOM temperature were taken from thermistors onboard the MitySOM-QC6490.

Power for the SOM was measured using the LTC2945 current monitor, with +4.0V provided on the 3V7-BAT input supply.

MitySOM-QC6490 DevKit without Cooling (No Heatsink etc.)¶

For this set of testing, a stock revision -3 MitySOM-QC6490 DevKit board and a MitySOM-QC6490 model 6490-EX-4X8-RL module was evaluated. The MitySOM-QC6490 was programmed with 1.1 SDK qcom-multimedia image. Results are shown in the table below.

Scenario	SOM Power (W)	DDR Rise (C)	PM7325 Rise (C)	PM7250B Rise (C)	CPU Rise (C)	GPU Rise (C)	SoC Package Rise (C)	SOM Rise (C)	Ambient Temp (C)	Test Duration (s)
Sleep	TBD	TBD	TBD	TBD	TBD	TBD	TBD	TBD	TBD	TBD
Linux Command Prompt	0.77	10.2	8.3	6.4	10.0	9.8	9.3	7.8	24.5	1500
One CSI Camera Stream to DisplayPort	1.25	16.0	11.4	9.5	15.8	14.7	13.0	11.4	24.5	400
Three CSI Camera Streams to DisplayPort	3.03	27.3	18.5	15.8	28.0	25.0	20.9	18.9	23.0	777
AI Face Detection	1.44	15.2	10.3	7.9	15.0	13.8	11.3	9.8	23.0	137
AI Parallel Inference	3.89	46.1	30.4	27.3	45.2	40.1	34.6	32.3	23.0	720
Stress-NG - CPU	6.34	60.0	45.5	35.8	68.5	53.2	45.8	40.1	23.5	500
Stress-NG - HDD	5.36	47.5	44.0	35.8	47.1	45.5	44.7	40.0	23.5	500
Stress-NG - IOMix	5.5	47.5	43.3	35.8	50.8	44.9	44.4	39.9	23.5	500
Stress-NG - VM	5.54	58.6	45.2	35.8	66.0	52.5	45.8	40.1	23.5	500
MemTester	2.73	33.8	22.5	19.0	37.2	29.2	24.6	22.3	23.0	567
FIO to UFS	2.72	19.5	19.8	12.2	19.5	18.0	16.2	13.9	23.0	55

Recreating Above Scenarios¶

In order to recreate the scenarios, the following commands can be run.

• Sleep
  • Mitysom-QC is in sleep mode (lowest power) state
• Linux Command Prompt
  • Run the sensors command after logging in to embedded Linux.
• CSI Camera
  • First
    • export XDG_RUNTIME_DIR=/dev/socket/weston && export WAYLAND_DISPLAY=wayland-1
  • 1 OV9281 Streaming to DisplayPort
    • gst-launch-1.0 -e qtiqmmfsrc name=camsrc camera=0 ! video/x-raw,format=NV12 ! waylandsink enable-last-sample=false fullscreen=true
  • 3 OV9281 Streaming to DisplayPort
    • gst-launch-1.0 -e qtivcomposer name=mixer sink_0::position="<0, 0>" sink_0::dimensions="<640, 360>" sink_1::position="<640, 0>" sink_1::dimensions="<640, 360>" sink_2::position="<0, 360>" sink_2::dimensions="<640, 360>" mixer.src ! queue ! waylandsink enable-last-sample=false fullscreen=true sync=false async=true qtiqmmfsrc name=camsrc_0 camera=0 ! queue ! video/x-raw, format=NV12, width=640, height=360, framerate=30/1 ! queue ! mixer.sink_0 qtiqmmfsrc name=camsrc_1 camera=1 ! queue ! video/x-raw, format=NV12, width=640, height=360, framerate=30/1 ! queue ! mixer.sink_1 qtiqmmfsrc name=camsrc_2 camera=2 ! queue ! video/x-raw, format=NV12, width=640, height=360, framerate=30/1 ! queue ! mixer.sink_2
• AI Face Detection: https://docs.qualcomm.com/doc/80-70018-50/topic/gst-ai-face-detection.html
• AI Parallel Inference: https://docs.qualcomm.com/doc/80-70018-50/topic/gst-ai-parallel-inference.html
• Stress-ng
  • stress-ng --thrash --cpu 7 --hdd 7 --iomix 3 --vm 4 --tz --verify
• MemTester
  • memtester 2G 1
• FIO to UFS
  • fio --name=ufs-test --filename=/root/ufstestfile --size=2G --rw=write --bs=256k --iodepth=16 --numjobs=1 --ioengine=libaio --direct=1 --loops=10 --verify=crc32c