AVR-Chat

I have a remote control transmitter design where I'm trying to put the
Tiny15 into Power Down mode. But although it appears to go into power
down, it is still drawing 0.45mA. The data sheet says it should go down
to about 2uA. I have eliminated all external circuitry from the design,
it's just the tiny, so it's not a problem with connections to its pins.

Has anyone done Power Down and got down to the 2uA in the data sheet?


This is the code to put it into sleep

	in tempB,mcucr
	andi tempB,~((1<<SE)|(1<<SM1)|(1<<SM0))
	ori tempB,(1<<SE)|(1<<SM1)
	out mcucr,tempB
	sleep

-- 
Tim Mitchell
tim@sabretechnology.co.uk
http://www.sabretechnology.co.uk

On Mar 24, 2006, at 3:46 AM, Tim Mitchell wrote:

> I have a remote control transmitter design where I'm trying to put the
> Tiny15 into Power Down mode. But although it appears to go into power
> down, it is still drawing 0.45mA. The data sheet says it should go  
> down
> to about 2uA. I have eliminated all external circuitry from the  
> design,
> it's just the tiny, so it's not a problem with connections to its  
> pins.
>
> Has anyone done Power Down and got down to the 2uA in the data sheet?
>
>
> This is the code to put it into sleep
>
> 	in tempB,mcucr
> 	andi tempB,~((1<<SE)|(1<<SM1)|(1<<SM0))
> 	ori tempB,(1<<SE)|(1<<SM1)
> 	out mcucr,tempB
> 	sleep
>

Have you got the peripherals turned off?

- Bandgap Reference (turned on if you have BOD enabled (BODEN fuse))
- Watchdog (WDE) (15uA) (also used for level-triggered or pin-change  
interrupt to wake from sleep)

With the watchdog timer all the way off, the only way to wake from  
sleep is the RESET pin, so I assume that you are using the watchdog  
timer.

I'm not sure whether Power Down mode disables the BOD reset or not;  
it may turn off the BG reference too.

-- 
Ned Konz
ned@bike-nomad.com

On Mar 24, 2006, at 3:46 AM, Tim Mitchell wrote:

> I have a remote control transmitter design where I'm trying to put the
> Tiny15 into Power Down mode. But although it appears to go into power
> down, it is still drawing 0.45mA. The data sheet says it should go  
> down
> to about 2uA. I have eliminated all external circuitry from the  
> design,
> it's just the tiny, so it's not a problem with connections to its  
> pins.
>
> Has anyone done Power Down and got down to the 2uA in the data sheet?
>
>
> This is the code to put it into sleep
>
> 	in tempB,mcucr
> 	andi tempB,~((1<<SE)|(1<<SM1)|(1<<SM0))
> 	ori tempB,(1<<SE)|(1<<SM1)
> 	out mcucr,tempB
> 	sleep


Some more things to look at:

- You say you have eliminated "all external circuitry"; are you sure  
that you have all input pins either pulled up (possibly by the  
internal pullups) or down? Digital input pins at in-between voltages  
can draw quite a bit of current.

- Is it possible that you have an internal pullup turned on and are  
then grounding that input? This would add 250uA or so of pin current  
to your supply current.

-- 
Ned Konz
ned@bike-nomad.com