Using the 3V3 pin to power devices?

Forum 2005-2010 (read only) Hardware Interfacing
1

I have just started experimenting with my Diecimila and the Wii Nunchuck. As the nunchuck operates on 3.3 volts I started wondering if I could use the 3V3 pin to power it... The 3.3 V reference voltage pin found on the USB Arduinos is provided by the FTDI USB interface chip so I checked the FT232R data sheet and found this:

external circuitry requiring a 3.3V nominal supply at a current of around than 50mA could also draw its power from the 3V3OUT pin, if required.

The data sheet for the accelerometer inside the nunchuck (ADXL330) states that the typical current consumption at 3.6 V supply voltage is a measly 375 [ch956]A. I don't know what other chips the controller holds inside but I think it seems pretty safe to use the 3.3 V supply provided by the FT232R. Or what do you think?

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hi,
i don't want to answer your question, because i just don't know. but did you take the ADXL330 out of the controller? i was thinking of getting myself one yesterday to just use the accelerometer. (i hate mail order) the whole controller probably sucks more than just 375 ?A though.

i'd recommend to get a 3.3v power-regulator or build a voltage divider (i think that this would be ok for such a tiny current, but rather ask someone else before going into serial production ;-)). there are other means as well to get the right voltage using diodes.

still your question is a good one, and being able to use onboard 3.3v (within limits) would sure be nice to know.

//kuk