NERP - Not Exclusively Raspberry Pi Message Board › Raspberry Pi GPIO pin max current
I became curious after the meeting last night and found some good links which may be of interest.
Discussion of max current for GPIO pins:
From that discussion there were two great finds.
"GPIO pads control"
documentation by SoC engineer Gert van Loo which concludes 'all the electronics of the pads are designed for 16mA.'
Explains relationship between voltage, current and impedence. It summarizes: "A maximum of 16mA per pin with the total current from all pins not exceeding 51mA.''
"When the Pi was designed, they used a figure of 3mA per GPIO pins in determining if the regulator could supply enough current. Hence the simple 3mA limit mentioned before. However, if not all the pins are supplying current then you can divert those pin’s share of the current into the ones you are using. Hence the total recommended current limit of 17 * 3 = 51mA."