Amperage Limits

[espruino-discuss3]

Posted at 2016-12-08 by .Neil

I see some examples where espruino pins are used to power LEDs. Does anyone know how much current one of these pins can source? Or sink?

("sink" as in set to FALSE and act as a 0v ground for an external device. Sinking traditionally has a higher current limit as in the old 555 timer IC)

-Neil

[espruino-discuss3]

Posted at 2016-12-08 by countxerox

I read somewhere in theses forums each pin can source or sink 20mA/25mA but no more than 150mA for all pins. Also there's something regarding the 3.3v? Have a look at he RC Car Control and GPS Powered Using Pins in the Projects forum.

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Posted at 2016-12-08 by @allObjects

It's the datasheet's call. Drawing - sourcing or sinking - more than 20..25 mA on a pin delivers just not the expected voltages anymore. The total of 150mA is what the die can handle max without 'burning' up...

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Posted at 2016-12-09 by @gfwilliams

As @countxerox and @allObjects have said, it's about 20mA per pin - but it varies depending on the chip so it's best to look in the datasheet - where there's loads of in-depth info about the pins (some are different to others)

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Posted at 2016-12-09 by .Neil

Thanks all.

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Posted at 2016-12-09 by @allObjects

@.Neil, to provide you with some ideas, take a look at conversation about GPS powered by Espruino pin(s).

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Posted at 2016-12-09 by DrAzzy

I remember being unable to find the max current per pin on an STM32F1 datasheet (for the original Espruino). Like, is it "you can try to draw as much current as you want from a pin, but the most you'll get is 20mA or so"? On the AVR's in arduino-land, there's a max recommended current per pin, and an absolute max current per pin (which will be exceeded if you short a pin to ground and try to drive it high, for example).

I think it would be a very good idea to find that spec for the official espruino boards at least, and list it clearly on the reference pages.

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Posted at 2016-12-10 by @gfwilliams

Yes - good idea...

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Posted at 2016-12-19 by countxerox

The datasheet for pico's chip lists the current characteristics in Table 12.

Output current sunk/sourced by any I/O and control pin 25mA. Total
output current sunk/sourced by sum of all I/O and control pins
12omA

This current consumption must be correctly distributed over all I/Os
and control pins. The total output current must not be sunk/sourced
between two consecutive power supply pins referring to high pin count
LQFP packages.