RE: [avr-chat] AVR on 1 AA bat with just 1 L and 1 C

[Eric Fu]

I think the switching frequency must be sufficiently high to get this to
work. And the switching current must be controlled low enough to avoid
pin damage. It is a good idea though if I'm in the middle of the desert.
For where I am, I would rather use a proper DC/DC boost converter or
charge pump.

Eric Fu

 


> -----Original Message-----
> From: address@hidden 
> [mailto:address@hidden
>  On Behalf Of address@hidden
> Sent: Thursday, March 24, 2005 8:45 AM
> To: address@hidden
> Subject: [avr-chat] AVR on 1 AA bat with just 1 L and 1 C
> 
> 
> Sorry but I just have to share my perverse idea with you.
> 
> I think e.g. ATtiny15 could be operated from just one 1.5V 
> battery using just one coil and one capacitor and mis-using 
> the AVR chip to act as a switched power supply for itself. Look:
> 
>                     ....................
>          coil       :       AVR        :
>     -------uuuuu----:port           vcc:----
>    |                :pin    gnd        :    |
>   ---               :..................:   --- cap
>    =  bat                    |             ---
>    |                         |              |
>     -------------------------+--------------
> 
> Strange, is not it? Yes, battery goes to port pin only. Yes, 
> on vcc, there's just the cap and nothing else. But wait, I 
> think it could
> work:
> 
> 1) AVR grounds 'port pin', current flows via coil
> 
> 2) AVR leaves 'port pin' floating, current still flows via 
> coil and now it charges the cap via internal over-voltage 
> protective diode on the pin
> 
> Did I miss something?
> 
> Well, how to switch it on... Maybe a pushbutton between port 
> pin and gnd :-) ?  Not a big offense in a perverted design 
> like this one...
> 
> Bye
> 
> Vaclav
> 
> P.S. Sorry for being off-topic maybe even on avr-chat but 
> there is nobody around who would listen to me just now ;-) 
> (Disclaimer: I try to do sane designs most of the time, 
> however just now it is not the case. ;-) )
> 
> 
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