DS1307 RTC and Supercap - trickel charge
Archiver
Posts: 46,084
--- In basicstamps@yahoogroups.com, PatM <pmeloy@s...> wrote:
> Actually, as mentioned by someone earlier. The 1307 doesn't include
a
> trickle charger. I assumed it had one as well but, check the
datasheet. Not
> a single peep about any form of charger on the vbat circuit.
>
> Not really an issue for me since I'd intended to go with a 3v coin
cell from
> the start anyway.
The not on Vbat about...
"UL recognized to ensure against reverse charging current when used
in conjunction with a lithium battery."
...threw me. The 1302 does have the same legal note and a charger
and I am slighly more familiar with that chips' data sheet.
Guess that is one really good reason the 1307 is not listed on the
app note on trickel chargers.
Dave
>
> >
Original Message
> > From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> > Sent: March 15, 2004 3:17 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: DS1307 RTC and Supercap
> >
> > I dug a little deeper on the Dallas site and found the app note on
> > enabling the trickle charger. It is shipped OFF and must be
turned
> > on.
> >
> > However, the note is written for the 1302, and does not explicitly
> > list the 1307 chip, so I do not know if it works for that one.
> >
> > http://pdfserv.maxim-ic.com/en/an/app82.pdf
> >
> >
> > Charging for a rechargable battery or SuperCap can be selected in
> > software, but it is required that you do that.
> >
> > Also, I have not tried to use the trickle charger, but it appears
> > that it defaults to the no-charge on start-up and may need to be
told
> > to trickel charge after a complete battery drain or change of both
> > power supplies.
> >
> > All the calculations for charging the Super Cap are on that sheet.
> >
> > Dave
> Actually, as mentioned by someone earlier. The 1307 doesn't include
a
> trickle charger. I assumed it had one as well but, check the
datasheet. Not
> a single peep about any form of charger on the vbat circuit.
>
> Not really an issue for me since I'd intended to go with a 3v coin
cell from
> the start anyway.
The not on Vbat about...
"UL recognized to ensure against reverse charging current when used
in conjunction with a lithium battery."
...threw me. The 1302 does have the same legal note and a charger
and I am slighly more familiar with that chips' data sheet.
Guess that is one really good reason the 1307 is not listed on the
app note on trickel chargers.
Dave
>
> >
Original Message
> > From: Dave Mucha [noparse][[/noparse]mailto:davemucha@j...]
> > Sent: March 15, 2004 3:17 PM
> > To: basicstamps@yahoogroups.com
> > Subject: [noparse][[/noparse]basicstamps] Re: DS1307 RTC and Supercap
> >
> > I dug a little deeper on the Dallas site and found the app note on
> > enabling the trickle charger. It is shipped OFF and must be
turned
> > on.
> >
> > However, the note is written for the 1302, and does not explicitly
> > list the 1307 chip, so I do not know if it works for that one.
> >
> > http://pdfserv.maxim-ic.com/en/an/app82.pdf
> >
> >
> > Charging for a rechargable battery or SuperCap can be selected in
> > software, but it is required that you do that.
> >
> > Also, I have not tried to use the trickle charger, but it appears
> > that it defaults to the no-charge on start-up and may need to be
told
> > to trickel charge after a complete battery drain or change of both
> > power supplies.
> >
> > All the calculations for charging the Super Cap are on that sheet.
> >
> > Dave