[Microbit-Python] Microbit operating voltage range

[Jim Mussared]

The NRF51822 chip on the micro:bit is designed to run down to 1.8V --
internally it actually has built-in voltage conversion so even when you're
supplying 3.3V it's still running at 1.8V. I haven't seen the schematics,
so I'm not sure exactly which mode it's in though - I had a quick look
under the microscope and it seems like it's probably not using the DC/DC
converter mode and more likely the LDO.

Either way - it's designed to run down to low voltages and in LDO mode it
will work between 1.8 and 3.6V.

However, the things you connect to it might not be happy with 1.8V. Also
there's no LED driver on the board, and there's 5 resistors that look
fairly likely to be current limiting for the matrix, so they'll be pretty
dim at 1.8V.

In general though - powering devices from batteries --one easy way around
this problem is a DC/DC converter - this module looks like a great option
(price, size, etc): https://www.pololu.com/product/2561  (acts as a boost
converter for 0.5 - 3.3v, linear regulator for 3.3 - 5.5v input). There's a
slightly cheaper option without the auto-shutdown (https://www.pololu.com/
product/2563). This will let you use anything from 0.5 to 5.5V.

Also another option if you want to use a bigger battery pack (e.g. 4xAA) is
a buck/boost converter so you can drive it at any voltage from 2.7-12V.
https://www.pololu.com/product/2122

I'm sure cheaper modules exist too.

The other good thing about the boost converter is that as the battery
discharges and drops voltage, the device will continue to operate at 3.3V.

On 18 August 2016 at 07:07, M.-A. Lemburg <mal at egenix.com> wrote:

> On 17.08.2016 22:39, fresh.bread via Microbit wrote:
> > Perhaps a bit off topic, being a general hardware question, but I can't
> > seem to find the appropriate forum to ask the question, but does anyone
> > know what the Microbit's operating voltage range is.
> >
> > 1. I have seen it suggested that taking it above 3V isn't a good idea,
> > is that true?
> > 2.  Has anyone measured the minimum operating, I coupled it to a pair of
> > rechargeable NiMH  cells,  these were freshly charged and putting out
> > 2.6V. My patience ran out before the cells.. Will it work off 2.4v (i.e
> > a pair of tired NiMH cells)
>
> You might find this test interesting:
>
> http://www.reuk.co.uk/wordpress/microbit-power-consumption/
>
> Apparently, 1.83V is enough to get it working.
>
> --
> Marc-Andre Lemburg
> eGenix.com
>
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