Re: gEDA-user: CR2032 with supercap, was Re: [SOT] suggestion for a SMT switch

[Jason <geda@xxxxxxxxxxxxxx>]

Gabriel Paubert wrote:
> However, you want to have power for longer than this device. The PowerStor
> series from Cooper Bussmann might fit your bill (1kHz ESR down to 0.2 Ohms), 
> but they are neither cheap nor very small (especially the lowest ESR PA
> series):
> 

I found the TPL-0.5/8X12F [1] boost supercap around 1am this morning. 
It's 2.7V, 0.5F, and has a 1.5ohm DC ESR in a 8mm dia by 12mm long 
package.  It's still a little too big, but there is a smaller version, 
the TPL-0.5/6X9F that isn't UL approved yet.  Same characteristics as 
above, except that it has a 2.2 ohm DC ESR, in a 6.3mm dia by 9mm long 
package.  Sweet!  I have an email out to those guys about max current 
draw and eta, we'll see.

With some hacking, I can use one of the pic's output pins to provide it 
power at 2.3V, and then I can shut off the circuit when I don't need it. 
  Otherwise, I may just do a diode drop...

Now, my concern is recharging interval for the supercap.  I may have to 
do a current-limiting resistor, not sure yet.

thx,

Jason.


[1] - 
http://www.tecategroup.com/store/index.php?main_page=product_info&cPath=18_19_44&products_id=84


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