Power problem

[frankeltham]

Can anyone help a PICAXE new boy please?

I am trying to design a little circuit using the PICAXE-08M. I have been prototyping using the little demo board.
I need it to consume as little power as possible. And as it only needs to do things infrequently I can do a NAP or SLEEP.

But with no loads and a 6 line programme running it is using 0.5mA and 0.4mA in Sleep.
Too much.
Note: With the sameish porgramme running on a PICAXE-18X it uses about 9 microamps in Sleep?

I have also tried several 08Ms no difference.
I have underclocked it to 32KHz and the power droops to about 0.3mA which is miles more than Microchips datasheet says it should use.
I have checked my soldering and even pulled out the chip and measured the current - almost zero (please don't go on about capacitor leakage).

Can anyone tell me whats going on and why this chip uses 50x the power of an 18X both in Sleep mode?

 

[kranenborg]

Hi,

I have had a similar issue (but with the 18x) and it was related to the fact that unused inputs were left floating instead of tied to ground. As a result switching occurs due to 50Hz pick-up, which leads to increased current consumption. See this link:

http://www.rev-ed.co.uk/picaxe/forum/Topic.asp?topic_id=2321&forum_id=15&Topic_Title=problem%2B%2Bwith%2Bgetting%2Bvery%2Blow%2Bpower%2Bconsumption&forum_title=No+new+posts+please%21+9

So, have you tied all your unused 08M inputs to ground (but take care not to accidently tie an OUTPUT directly to ground!)?

By the way, what is the application?

Regards,

Jurjen
http://www.kranenborg.org/ee/picaxe

Edited by - kranenborg on 11/11/2005 8:08:14 PM