06 February 2013
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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.
| Test | Model B | Model A | Model A with a switching regulator |
| Bare Board | 71.2mA | 69.7MA | 95mA |
| With Com Pi board (1-wire disconnected) | 74mA | 73.7mA | 99mA |
| As above with an 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 a 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.
The switching regulator was soldered on leads to test the current consumption.
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