Finally had some time to put together a small prototype board with the switching power supply and setup the Rpi with low profile microSD and root on a small USB memory drive.
Here is how the whole thing looks like:
And from the bottom:
On the connector besides input power to the switching power supply I've the UART Tx and Rx signals for the serial console just used for initial setup.
Instead of a full size SD card or a microSD with the SD adapter I used Adafruit's low profile microSD adapter:
https://www.adafruit.com/product/966
The root file system is mounted via USB on a 16GB memory stick from Verbatim:
http://www.amazon.com/SanDisk-Cruzer-Flash-Drive-SDCZ33-016G-B35/dp/B005FYNSZA
The case is obviously Adafruit's crystal-clear acrylic enclosure:
https://www.adafruit.com/product/859
If you didn't notice, I also added a small push button for RESET.
The power supply is based on Texas Instruments TPS54232D.TPS54232D. SWIFT Step Down DC/DC converter:
http://www.ti.com/product/tps54232
It can take from 7V to 28V and deliver up to 2A 5V output
Here is a close up to the prototype board:
And here are the schematics:
As time permits I may design a pcb layout using SMT components that will make the board much smaller.
So far the whole thing seems to be working OK, with the USB drive mounted, overclocked at 900MHz (500MHz for SDRAM and 275MHz for gpu) and ethernet with active traffic (I'm using the Rpi via ssh and VNC) it takes about 260mA at 9V.
There is a substantial different in temperature from the Rev 1.0 board, the LAN9512 now runs barely warm, still with the case fully closed touching the case feels worm and a thermocouple probe it shows about 42C inserted through the flat cable opening.
-J
