What Is the DS1307? Basic I2C RTC: Specs and Uses
The DS1307 is a basic, cheap I2C real-time clock (RTC) IC. It keeps time on a backup battery, holds 56 bytes of NVRAM and needs an external 32.768 kHz crystal to run (address 0x68, 5 V). Without temperature compensation it can drift by minutes per month; for precision the DS3231 is preferred.
The DS1307 is a basic, cheap real-time clock (RTC) IC. It communicates over I2C, keeps time with a backup battery and holds a small NVRAM. It needs an external 32.768 kHz crystal to run. For the concept, see what is an RTC · what is I2C.
What is the DS1307 used for?
Simple clock/calendar, timestamps and low-budget projects. It keeps the clock running through a power loss thanks to the battery. If you need high precision, the DS3231 is better.
Highlights
| Parameter | Value |
|---|---|
| Type | Basic I2C RTC |
| Interface | I2C (address 0x68) |
| Crystal | Needs an external 32.768 kHz |
| Extra | 56 bytes NVRAM, square-wave output |
| Supply | 5 V (battery-backed) |
Watch out: accuracy
Without temperature compensation, the DS1307 can drift by minutes per month depending on ambient temperature and crystal quality. For critical timing choose the DS3231.
Limitations
- An external crystal is required; it drifts with temperature (low accuracy).
- 5 V only (care on 3.3 V systems).
Equivalents and alternatives
- DS3231: with TCXO, far more accurate.
- DS1302: a 3-wire serial RTC.
- PCF8563: a low-power I2C RTC.
Find it in our catalog
Use the DS1307 search.