The DS1307 serial real-time clock (RTC) is a low-power, full binary-coded decimal (BCD) clock/calendar plus 56 bytes of NV SRAM. Address and data are transferred serially through an I2C, bidirectional bus. The clock/calendar provides seconds, minutes, hours, day, date, month, and year information. The end of the month date is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with AM/PM indicator. The DS1307 has a built-in power-sense circuit that detects power failures and automatically switches to the backup supply. Timekeeping operation continues while the part operates from the backup supply. Typical operating circuit.
The DS1307 serial real‑time clock provides seconds, minutes, hours, day, date, month and year information, with automatic leap‑year correction and selectable 12‑hour or 24‑hour mode. It includes a built‑in power‑sense circuit that switches to a backup supply when main power fails, allowing the clock to continue running.
The device operates from a 5 V supply, consumes less than 500 nA in battery‑backup mode, and is available in 8‑pin PDIP or SO packages. Detailed electrical characteristics, timing diagrams, and pin descriptions are provided for designers integrating the RTC into their systems.
| Supply Voltage (Vcc) | 4.5 V – 5.5 V |
|---|---|
| Backup Supply Current (Battery‑Backup Mode) | < 500 nA |
| Operating Temperature Range (Industrial) | -40 °C to +85 °C |
| Clock Frequency (SCL) | 0 – 100 kHz |
| SRAM Size | 56 bytes |
| Pin Capacitance (SDA, SCL) | 10 pF |
| Package Types | 8‑pin PDIP or 8‑pin SO |
The DS1307 operates from 0 °C to +70 °C for commercial use and from -40 °C to +85 °C for industrial temperature range.
The device includes 56 bytes of battery‑backed general‑purpose SRAM.
The DS1307 is offered in an 8‑pin PDIP (800 mil) and an 8‑pin SO (150 mil) package, with lead‑free and industrial‑temperature variants.