Keeping track of the Date and Time despite power loss


I'm considering something like this IC to keep track of date and time in my project (an automated sprinkler system):

Here is the data sheet:

Looks pretty cool with the snazzy I2C interface and I can use a small watch battery for a backup power source (the device has pins for backup power).

What I don't like about the IC is that it is surface mount which means I have to make an adapter for my project which is currently a breadboard project and I will need an oscillator. Does something like this exist in a through-hole technology form with integrated clock?

Is there a better way for me to do what I want to do here (like make a backup power setup for the Arduino or something)?


I happened to be browsing over at before reading this, and I recalled they had a RTC in an electronic brick format:

Oh cool! I like not having to do my own PCB layout (I suck at it...need practice...can't believe how long I've been an EE without really getting a handle on it...).

Would a Chronodot be suitable?

I2C and +/- 2ppm accuracy.


After my initial posting, I wandered over to adafruit, and saw a RTC better for a breadboard environment:

The one posted by el_supremo also looks like it would work, and it appears to be more accurate than the above RTC.

Hmm... idk. They all look like super great options. I might go with the chronodot, but the price seems really high to me... at some point I have to wonder if hacking a Timex wrist watch would somehow be more practical (I know it wouldn't, I jest).

Add a crystal to this
and a coin cell battery/holder.
I've them to be pretty accurate.
DS3232 may be more accurate, but not available as a DIP
but its 'larger' pins (relative to other SMT parts) are not too hard to solder on a breakout board.

These are very small and include a temperature sensor and NV storage:

--- bill