DIY DS1307 Real Time Clock circuit

I am building my own DS1307 Real Time Clock circuit which I will be using for some of my projects. I know that DS3231 is a better solution but I have a bunch of DS1307 chips lying around the house. I thought I might as well put them to good use.

I was looking for a DIY DS1307 circuit and I noticed that most of the time, the circuit seems to include the following components:

DS1307 RTC chip – 1
32.768 Khz (12.5 pF) generic quartz watch crystal – 1
10K ¼ w Resistor – 2
12mm 3V Lithium Coin Cell (CR2032) – 1
12mm Coin Cell Holder – 1
Circuit Board – 1

But one particular website, stated that you also need a 100nF Ceramic Capacitor which should be connected like this:

Is this capacitor really needed and does it have to do anything with the accuracy of the Real Time Clock circuit? I thought, perhaps it is useful when the main power source is lost and the circuit switches over to battery power and may be this capacitor makes sure the transition is smooth?

Cheers.

arduinoware:
I am building my own DS1307 Real Time Clock circuit which I will be using for some of my projects. I know that DS3231 is a better solution but I have a bunch of DS1307 chips lying around the house. I thought I might as well put them to good use.

I was looking for a DIY DS1307 circuit and I noticed that most of the time, the circuit seems to include the following components:

DS1307 RTC chip – 1
32.768 Khz (12.5 pF) generic quartz watch crystal – 1
10K ¼ w Resistor – 2
12mm 3V Lithium Coin Cell (CR2032) – 1
12mm Coin Cell Holder – 1
Circuit Board – 1

But one particular website, stated that you also need a 100nF Ceramic Capacitor which should be connected like this:

Is this capacitor really needed and does it have to do anything with the accuracy of the Real Time Clock circuit? I thought, perhaps it is useful when the main power source is lost and the circuit switches over to battery power and may be this capacitor makes sure the transition is smooth?

Cheers.

Yes - the datasheet also mentions it. It's a "bypass" capacitor and should be placed as close as possible to those terminals of the DS1307. Not having anything to do with the switching to battery mode, but rather possible fluctuations to the power at any time.

justjohn:
Yes - the datasheet also mentions it. It's a "bypass" capacitor and should be placed as close as possible to those terminals of the DS1307.

Thanks for explaining. So, basically I should short negative and 5V by using that capacitor, right? (through the legs of the capacitor)? Is that right?

Should I do this on the DS1307 circuit board or between the arduino's negative and 5V PINs?

If I'm building the DS1307 circuit on a breadboard, where would be the best place to install this capacitor in a circuit like this?

Cheers.

arduinoware:
Thanks for explaining. So, basically I should short negative and 5V by using that capacitor, right? (through the legs of the capacitor)? Is that right?

Should I do this on the DS1307 circuit board or between the arduino's negative and 5V PINs?

If I'm building the DS1307 circuit on a breadboard, where would be the best place to install this capacitor in a circuit like this?

Cheers.

If used, you should put it as close as possible to the pins of the DS1307 since the Arduino would already have one. You actually don't "really" need one for something like this because the Arduino already has one. But "technically speaking," if this was on a circuit board, near various other components or traces that could impose glitches on the power lines, it would be best to have it in place.

justjohn:
If used, you should put it as close as possible to the pins of the DS1307 since the Arduino would already have one. You actually don't "really" need one for something like this because the Arduino already has one. But "technically speaking," if this was on a circuit board, near various other components or traces that could impose glitches on the power lines, it would be best to have it in place.

Thanks a lot.

You're welcome. Have a great day. :slight_smile: