Gracias Hector!
Anyway, the HT1380 datasheet says that the logic voltage at the pins should
be VCC+0.3V (max) and using the Diode I will get VCC + 0.7V wich, as said on
the datasheet, can damage the chip over time...

Actually that was why I was looking for help on this. I first think on the
diode, but that would mean that I have to add also a level translator
(specially anoying for the RTC -> PIC part) and my real problem is that I
don't have more space on the PCB...

Best regards,

Mauricio Jancic
Janso Desarrollos - Microchip Consultants Program Member
info@janso.com.ar
www.janso.com.ar
(54) 11 - 4542 - 3519
 

> -----Original Message-----
> From: piclist-bounces@mit.edu 
> [mailto:piclist-bounces@mit.edu] On Behalf Of Hector Martin
> Sent: Thursday, May 12, 2005 5:17 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] RTCs and SUPERCAPs
> 
> I'd say the typical thing would be to "independize" the 
> supply with a diode and add the supercap. That way you 
> maintain power while preventing the supercap from discharging 
> through other parts of the
> circuit:
> 
>       |\ |
> +5V---| )|----+-------------------+
>       |/ |    |                   |VCC
>               |+              +-------+
>             ----- SUPERCAP    |  RTC  |
>             -----             +-------+
>               |                   |GND
> GND-----------+-------------------+
> 
> Something like that should work. I think.
> 
> 
> Mauricio Jancic wrote:
> > Yes, but the problem is that the HT1380 doesn't have an independent 
> > BAT input...
> > 
> > Mauricio Jancic
> > Janso Desarrollos - Microchip Consultants Program Member 
> > info@janso.com.ar www.janso.com.ar
> > (54) 11 - 4542 - 3519
> >  
> > 
> 
> 
> --
> Hector Martin (hector@marcansoft.com)
> Public Key: http://www.marcansoft.com/hector.asc
> 
> --
> http://www.piclist.com PIC/SX FAQ & list archive View/change 
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