Wednesday 06 February 2013
The new Raspberry Pi model A arrived today after a mixup where Farnell sent us another model B yesterday.
The new Model A on the left with a Com Pi board and Wifi dongle. Older Model B on the right.
As the new Model A is supposed to use a lot less power than the older model B, we tested both boards under different conditions using a TTi 1705 bench multimeter on a regulated 5V supply.
The tests were done using the standard Model B, the Model A and the Model A with the linear regulator removed and a switching regulator for the 3.3V fitted. The switching regulator used was a TI PTH08T240W which was overspecified for this task which explains the higher power usage at the lower current draw as it is less efficient at lower power usage.
||Model A with a switching regulator
|With Com Pi board (1-wire disconnected)
|As above with an SD card
311mA Login prompt
111mA Login prompt
128mA Login prompt
|As above with Wifi card
450mA Login prompt
470mA Downloading file
200mA Login prompt
220mA Downloading file
217mA Login prompt
260mA Downloading file
|As Above with a wired network
366mA Login prompt
405mA Downloading file
|Halt state (sudo shutdown -h now) with Com Pi
|Halt state (sudo shutdown -h now) without Com Pi
The old regulator was unsoldered from the board and also the video out to make the board lower for our planned solar monitoring system upgrade.
The switching regulator was soldered on leads to test the current consumption.