When I was testing this, I found that leaving the MCLR open caused the curr= ent to float all over the range. I tried making all the unused pins outputs= .. I was at my end of patience when I discovered that pulling MCLR down made= the current low (70nA) and really stable. I saw the paragraph about sleep = mode and unused inputs. I tried pulling all unused pins low. Then I tried p= ulling them up with 15K (using a resistor network). Neither of these made m= uch difference. The MCLR pull down was a dramatic solution that I happened = upon. I still wonder why.=20 ----- Original Message -----=20 From: "Bob Blick" <bobblick@ftml.net>=20 To: "Microcontroller discussion list - Public." <piclist@mit.edu>=20 Sent: Wednesday, December 22, 2010 2:59:56 PM=20 Subject: Re: [PIC] low sleep mode current on PIC16F688=20 On Wed, 22 Dec 2010 17:55:30 +0000 (UTC), zipwize said:=20 > If MCLR is internal, why do I have to tie it low to get low sleep=20 > current? Is there a better way?=20 "A weak pull-up is=20 automatically enabled for RA3 when configured as=20 MCLR and disabled when RA3 is an I/O. There is no=20 software control of the MCLR pull-up."=20 So if it was MCLR you could leave it floating, but since you have it=20 configured as I/O(actually it can only be configured as input or MCLR,=20 not an output), it has no pullup and you need to deal with it=20 externally.=20 Bob=20 --=20 http://www.fastmail.fm - Same, same, but different...=20 --=20 http://www.piclist.com PIC/SX FAQ & list archive=20 View/change your membership options at=20 http://mailman.mit.edu/mailman/listinfo/piclist=20 --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .