DS1307

Real Time Clock Overview

The DS1307 is a low-power, full binary-coded decimal (BCD) real-time clock and calendar with 56 bytes of non-volatile SRAM. It communicates via an I2C bidirectional serial bus. The device tracks seconds, minutes, hours, date, month, day of the week, and year, including automatic leap-year compensation valid up to 2100. It operates in either 12-hour or 24-hour format. A built-in power-sense circuit detects failures and switches to a backup supply, ensuring continuous timekeeping. The chip supports standard mode I2C communication at 100kHz.

Real Time Clock Feature Summary

• Full BCD clock/calendar with automatic leap-year correction through 2100
• 56-byte battery-backed general-purpose RAM with unlimited writes
• Programmable square-wave output signal (1Hz, 4kHz, 8kHz, 32kHz)
• Automatic power-fail detect and switch circuitry for uninterrupted operation

Real Time Clock Applications

• Industrial control systems requiring precise time stamping
• Portable devices needing reliable battery-backed timekeeping
• Embedded systems utilizing I2C interfaces for data logging

Real Time Clock Procurement Notes

Verify the specific package variant required, such as PDIP-8 or SOIC-8, as electrical characteristics remain consistent across packages but physical dimensions differ. Confirm temperature range requirements; commercial grade covers 0°C to +70°C, while industrial grade extends to -40°C to +85°C. Ensure the ordering suffix matches the desired packaging format, including tube or tape-and-reel options, to align with assembly processes.

Real Time Clock Selection Notes

Select the appropriate temperature rating based on environmental conditions: DS1307+ for commercial use and DS1307N+ for industrial applications. Verify that the host microcontroller supports the standard I2C mode (100kHz), as fast mode (400kHz) is not supported by this component. Ensure external pull-up resistors are calculated correctly for SDA, SCL, and SQW/OUT pins to meet rise time specifications.

Real Time Clock Part Context

The DS1307 belongs to the Maxim Integrated RTC family, designed for simple, cost-effective timekeeping solutions. It serves as a slave device on the I2C bus, simplifying integration with various microcontrollers. The component eliminates the need for complex oscillator circuits by supporting standard 32.768kHz crystals directly on X1 and X2 pins.

Real Time Clock Replacement Considerations

Direct pin-compatible replacements within the same series include DS1307N+, DS1307Z+, and DS1307ZN+. Variants ending in 'T&R' offer tape-and-reel packaging for automated assembly. No functional upgrades are available within this exact part number; newer generations may require schematic adjustments.