Attiny vs. 555 timer current consumption

Hi there,

i'm making a battery powered beacon that sends a 10ms pulse every 5 seconds or so. I can achieve this either with a 555 timer or an attiny. I don't have have the MCU at disposal right now to measure the current consumption, but the 555timer while idle uses up 3mA, which does drain out the battery quite fast. Any idea how low could i get with an attiny performing this simple operation?

The data-sheet says that in active mode at 1MHz it uses up 300uA. Is this true and does it require some special preparations?


Nick Gammon has some useful data on low power operation.

Thanks, that's super informative.

Bare-bones board.

Sketch A above only draws 15.15 mA, a saving of 34.85 mA just by not using the development board. This would be accounted for by the fact that the development board has on it:

Voltage regulators (for +5V and +3.3V) A USB interface chip (for the USB port) A "power" LED

Sketch B above only draws 360 µA (0.360 mA) which is a LOT less. Still, you would expect about 31 mA less than the figure above for the Uno, so that sounds about right.

Also, with low power consumption I can put the multimeter on the "microamps" range which is more sensitive.

The initial outcome is that, to save power, forget about using a development board. Further savings (like reducing clock speed) would be overshadowed by the huge overhead of the voltage regulator and USB interface chip.

However this part confuses me. I'm not sure to what he is referring to. Sketch A is the barebones setup, and uses 15mA, then Sketch B uses 360uA. I'm confused.

The bare-bone board only has the Atmega328 plus the components in the picture. They basically created their own arduino without all the stuff the development board comes with.

Sketch A bare-bone is the code without sleep vs the code with sleep in sketch B.

Sorry not sure how else to word this :)

I see now. Thanks.

Hmm. Seems i'm indeed much better off with the attiny than a 555. I've been reading the datashet and from what i gather i should be hitting the 700uA mark at 4V, 1MHz. Active state. And substantially lower at idle. It's not even a contest then.

A Cmos 555, e.g. ICM7555, uses 30uA.
And can run on a lower voltage.
20Megohm (2x10Meg), 680ohm and 22uF (tantalum?) will get you the right timings, and only add 0.25uA.

30uA...hmm that sound nice. Didn't realize they exist in cmos. Thanks for the info.