Raspberry Pi model A vs Model B

Wednesday 06 February 2013

The new Raspberry Pi model A arrived today after a mixup where Farnell sent us another model B yesterday.

Raspberry Pi boards

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 where 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 over specified for this task which explains the higher power usage at lower current draw as it is less efficient at lower power usage.

Test Model B Model A Model A with switching regulator
Bare Board 71.2mA 69.7MA 95mA
With Com Pi board (1-wire disconnected) 74mA 73.7mA 99mA
As above with SD card 399mA Max
311mA Login prompt
197mA Max
111mA Login prompt
163mA Max
128mA Login prompt
As above with Wifi card 477mA Max
450mA Login prompt
470mA Downloading file
332mA Max
200mA Login prompt
220mA Downloading file
270mA Max
217mA Login prompt
260mA Downloading file
As Above with wired network 449mA Max
366mA Login prompt
405mA Downloading file
NA NA
Halt state (sudo shutdown -h now) with Com Pi 115mA 39mA 74mA
Halt state (sudo shutdown -h now) without Com Pi 111mA 35mA 70mA

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.

Raspberry Pi boards

The switching regulator was soldered on leads to test the current consumption.

Raspberry Pi boards