DS1307 Description
The DS1307 is a low-power serial real-time clock (RTC) with full binary-coded decimal (BCD) format for clock and calendar functions, and it includes 56 bytes of non-volatile SRAM. Data and addresses are transferred serially via an I2C bidirectional bus. The RTC provides accurate seconds, minutes, hours, day, date, month, and year information, with automatic adjustment for months with fewer than 31 days and leap years.
It supports both 24-hour and 12-hour formats with an AM/PM indicator. The DS1307 also features a built-in power-sense circuit that detects power failures and seamlessly switches to a backup power source, ensuring continuous timekeeping from the backup supply.
DS1307 Pinout
X1 (Pin 1): Oscillator Input - Connects to one side of a 32.768 kHz crystal oscillator or an external clock source.
X2 (Pin 2): Oscillator Output - Connects to the other side of the 32.768 kHz crystal oscillator.
VBAT (Pin 3): Battery Backup Input - Connects to a battery or supercapacitor to maintain timekeeping when the main power is off.
GND (Pin 4): Ground - Connects to the ground of the power supply.
SDA (Pin 5): Serial Data - This is the I2C data line for communication with the microcontroller.
SCL (Pin 6): Serial Clock - This is the I2C clock line for synchronizing data transmission.
SQW/OUT (Pin 7): Square Wave / Output - Can be used to output a square wave signal or as an interrupt signal depending on the configuration.
VCC (Pin 8): Power Supply Input - Connects to the positive supply voltage, typically 5V.
DS1307 CAD Models
Symbol
Footprint
3D Model
DS1307 Operating Circuit
DS1307 Block Diagram
DS1307 Timing Diagram
DS1307 Specification
| Feature | Specification |
| Power Supply Voltage (VCC) | 4.5V - 5.5V |
| Backup Battery Voltage (VBAT) | 2.0V - 3.5V |
| Current - Timing (Max) | 200µA @ 5V |
| Operating Temperature Range | -40°C - 85°C |
| Time Accuracy | ±2 minutes per month at 25°C |
| Time Format | HH:MM:SS (12/24 hours) |
| Date Format | YY-MM-DD-dd |
| Date Adjustments | Automatic adjustment for days of the month and leap years |
| Storage | 56B |
| Interface | I2C, 2-wire serial |
| Crystal Frequency | 32.768 kHz |
| Power Consumption | Typically 1 µA (in backup mode) |
| Output Pin | SQW/OUT pin for square wave or interrupt output |
| Package Options | 8-DIP |
DS1307 Features
- Completely Manages All Timekeeping Functions
- Real-Time Clock Counts Seconds, Minutes, Hours, Date of the Month, Month, Day of the Week, and Year with Leap-Year Compensation Valid Up to 2100
- 56-Byte, Battery-Backed, General-Purpose RAM with Unlimited Writes
- Programmable Square-Wave Output Signal
- Simple Serial Port Interfaces to Most Microcontrollers
- Low Power Operation Extends Battery Backup Run Time o Consumes Less than 500nA in BatteryBackup Mode with Oscillator Running
- Automatic Power-Fail Detect and Switch Circuitry
- 8-Pin DIP and 8-Pin SO Minimizes Required Space
- Optional Industrial Temperature Range: -40°C to +85°C Supports Operation in a Wide Range of Applications
- Underwriters Laboratories® (UL) Recognized
DS1307 Applications
Embedded Systems
Digital Clocks
Alarm Clocks
Industrial Equipment
Data Loggers
Routers
Medical Device
Vehicle Systems
DS1307 Package
The DS1307 uses an 8-PDIP (Plastic Dual In-Line Package) package. This package features a dual in-line configuration with eight pins arranged in a single row on either side, making it suitable for mounting on standard PCB (Printed Circuit Boards). The PDIP package offers ease of handling and soldering, providing a reliable connection for each pin.
DS1307 FAQs
How does the DS1307 keep time?
The DS1307 uses an internal quartz crystal oscillator to maintain accurate time. It updates the time and date continuously and compensates for leap years and months with fewer than 31 days.
What are the key benefits of using the DS1307?
The DS1307 offers precise timekeeping with automatic date adjustments, a built-in power-sense circuit for battery backup, and easy interfacing via the I2C bus.
How is the DS1307 interfaced with a microcontroller?
The DS1307 communicates with a microcontroller using the I2C serial bus, which requires only two lines: SDA (data line) and SCL (clock line).
