We're trying to think of ways to reduce heat generated by our custom board, and so far we have done the following:
- Reduce the CPU speed by half (227MHz)
- Force USB to 1.1 mode
- Force USB WLAN to 1MBit/s speed
- Enable power saving on USB WLAN (I somewhat doubt this helps)
- Lower DDR clock slightly
With these modifications the average board temperature was lowered by approximately 4 degrees, and I wonder what else could I try to lower the temperature generation further. I am assuming the lowering of CPU clock was the biggest win here.
I'm planning to test gating off Audio (SPDIF) since we don't need it, but would appreciate any additional ideas..
Lowering CPU core voltage could also help
http://cache.freescale.com/files/dsp/doc/app_note/AN4050.pdf
Hmm, that's a good idea. If I recall correctly, currently VDDD is at 1.5v (default by uboot for mx28 and mx23) - maybe I could try lowering it a bit and see if I have any instability issues (I remember playing around with it when we had some [unrelated] boot issues in previous designs but we had some stability problems).. Thanks for the suggestion!
Just a thought here - Have you explored using the low-power operation modes? (section 12.2.6 of the imx23 RM)? QUOTE: In many applications, it is desirable to minimize the power consumption of the memory controller and the memory devices. The memory controller provides various user-configurable low-power options to address power savings. In addition, a partial-array self-refresh option is included for mobile memory devices.
Changing to a mobile DDR memory may also have a significant impact but I suspect that's a bit more difficult to implement.