DS1337 running with battery only

Greetings :slight_smile:

I wanted to ask if i could connect a battery to the vcc pin and ground pin and connect the vcc of the i2c pins directly to the vcc of the arduino, or if this wont work.

if you didnt understanded me, here's a schematic:

Thanks :slight_smile:

~Straw

You'd need to keep the DS1337's Vcc separate from the system Vcc so the battery
can power the chip while the power is off.

What I don't understand is why you are using the DS1337 when the DS1338 (3.3V) or DS1307 (5V only) are designed for battery backup - the DS1337 doesn't have a Vbat
pin so can't do auto-switchover to battery for you.

So I need to connect the i2c pins to the battery instead to the system?
Iโ€™m using a arduino Pro Mini @3.3v. I originally ordered the 1307 but noticed before I wanted to connect it, that it only works with 5v,so I would burn the arduino. And my space is limited so I canโ€™t use a level shifter. I searched for a 1339,which is basically a 1307 but @3.3v,but I couldnโ€™t find one at eBay Germany

~Straw

But I'm gonna search for a 1338 in SO8 dimension :slight_smile:

~Straw

You need a DS1338-33 for 3.3V, I think I've seen them on eBay. Its code-compatible with the
DS1307 but allows the battery voltage to be higher than the Vcc (which the original DS1307
didn't as it compared the two voltages to determine whether to switch to backup mode)

Thanks :slight_smile:

Found one with Integrated Crystal and ordered it

~Straw