I just took an ampèremeter and measured the current that my Retrode draws from the USB port, with and without the 3.3V voltage converter, and also the additional current when cartridges are inserted and idle or busy. Turns out that typical current consumption will be between 20 and 50 mA. The extreme case is a Retrode with A2600 cartridge, with draws approx. 100mA, thereof 28.3 for the Retrode itself and 70 for the cart. Keep this in mind when you consider connecting the Retrode to the OTG port of mobile devices, which is specified to provide a maximum of 100mA.
| What? | 5V | 3.3V |
| Retrode | 28.3 mA | 17.1 mA |
| SNES cart | 9.8 mA (idle) 13.2 mA (busy) |
5.0 mA (idle) 9.2 mA (busy) |
| SEGA cart | 1.0 mA (idle) 11.9 mA (busy) |
0.2 mA (idle) 8.1 mA (busy) |
| A2600 cart | ca. 70 mA | n/a |
| N64 cart | 1.7 mA (idle) 20.6 mA (busy) |
1.5 mA (idle) 11.2 mA (busy) |
| GB cart | 5.1 mA (idle) 10.3 mA (busy) |
19.2 mA (idle) 24.4 mA (busy) |
| GBA cart | 0.1 mA (idle) 6.2 mA (busy) |
0.2 mA (idle) 5.7 mA (busy) |
Current ratings:
Retrode: 4/5 stars
Pandora: 4/5 stars
Delicious Pizza: Full 5 stars!
SCNR! :)
So basically, on a portable device it’s best to leave the 3.3V converter in all the time except for reading A2600’s which need the full 5V and only *might* work with an OTG port, depending on if it will output a full 100mA at its current battery level?
That’s right. Except for Game Boy Classic games (and the obvious problem with 2600 carts that don’t run at 5V), it appears as if the voltage adapter actually makes the system more energy-efficient.
Ooh looks like it’s time to make a green case.