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How much current/power can be drawn from iPhone 30-pin connector by external devices?

I googled it and failed to find some definitive answer for this. some say 50-100mA.

Update: I am aware of MFi program from Apple. Does it mean one must register before getting the official hardware specifications regarding 30-pin connector?

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3 Answers 3

I don't know in general, but after iOS 4.2 the maximum current you can obtain through the Apple camera connection kit it's just 20 mA.

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how about the upper limit? –  shibenyong Sep 10 '11 at 5:24
2  
It's worth noting that the camera connection kit outputs 5V, while the iPad only outputs 3.3V. Therefore, there is a DC-DC in-between, which may be the factor that limits the current. Also, I believe it would be more accurate to say it does not work with devices that request more then 20 mA. The checking is done using the "Required Current" field from when the device enumerates over USB, not actually measuring the real current draw. –  Fake Name Sep 10 '11 at 5:54
    
@FakeName Thanks for the update. –  shibenyong Sep 12 '11 at 3:42

Somewhere around 160 mA.

Kineteka sells a 30 pin breakout board and pin 18 supplies the 3.3 volts. I just connected a 500 ohm pot between pin 18 and ground and lowered the resistance while measuring the current. It tops out around 160 mA. Try it!

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It's just my personal experience, but I have successfully run an xBee 1 mW module off the iPad (and a 5th generation iPod nano. I did my testing with the nano, cause it's cheaper to replace if I damaged something).

1 mW xBee radios have a claimed current draw of 50 mA.

Sparkfun also have a iPhone-connector GPS, which has a current draw of 75 mA.

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