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What is the max current per GPIO pin on the 5V rail of the Pi Zero W? Also, can I power a 5V relay (4 channel, each requiring 15-20 mA) from this rail? If not, does anyone know of a 4 channel relay that I can use with this Pi? Thanks!

EDIT: This is the relay that I have

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  • There are no 5v gpio pins. I just read about a project were they powered the zero with 3v. They said the only thing that needs 5v are add on cards and USB devices.
    – PaulF8080
    Commented Mar 16, 2017 at 11:51
  • I'm using the provided microUSB for power, which is 5V, 2.4A
    – holtc
    Commented Mar 16, 2017 at 12:47
  • There is a 3.3v voltage regulator that converts the 5v. The lower voltage goes to all the chips.
    – PaulF8080
    Commented Mar 19, 2017 at 23:32

1 Answer 1

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The GPIO pins can source a maximum of 16mA safely. (In fact you CAN draw more, but this is outside the published specifications.)

I assume you are actually asking about the capacity of the 5V and 3.3V pins on the expansion header. The simple answer is that it varies!

See Raspberry Pi Power Limitations for some analysis. This does not directly mention the Pi Zero which has a minimal power circuit (let alone the Pi Zero W, AFAIK the schematic has not been released).

I am sure that you would be able to draw 80mA, given a decent power supply.

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  • So, using this: webofthings.org/wp-content/uploads/2016/10/pi-gpio.png, I would connect the VCC on the board to pin 2 or 4, the ground to 6, and the 4 IN pins to 4 GPIO pins (12, 16, 18, and 22 for example)? Unfortunately, this does not seem to be providing enough power to the relay. Am I doing something wrong?
    – holtc
    Commented Mar 16, 2017 at 12:35
  • Sorry, I am totally new with the Raspberry Pi
    – holtc
    Commented Mar 16, 2017 at 12:48
  • And the GPIO voltage is 3.3V right?
    – holtc
    Commented Mar 16, 2017 at 16:34
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    The max voltage produced by GPIO is 3.3V, but if you require 16mA you would be lucky to get 2V. The link includes links to test results.
    – Milliways
    Commented Mar 16, 2017 at 21:18

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