DS1307ZN

Real Time Clock Overview

The DS1307ZN+ is a low-power, full binary-coded decimal (BCD) serial real-time clock and calendar integrated circuit manufactured by Analog Devices Inc./Maxim Integrated. It includes 56 bytes of nonvolatile SRAM for data storage. The device communicates via an I2C bidirectional bus and tracks seconds, minutes, hours, day, date, month, and year with automatic leap-year compensation valid up to the year 2100. It operates within a supply voltage range of 4.5V to 5.5V and supports an industrial temperature range from -40°C to +85°C. The component utilizes a built-in power-fail detection circuit to automatically switch to a backup supply, ensuring continuous timekeeping.

Real Time Clock Feature Summary

• Full BCD clock/calendar with automatic end-of-month adjustment and leap-year correction valid through 2100
• 56-byte battery-backed general-purpose RAM supporting unlimited writes
• I2C serial interface compatible with standard mode (100kHz clock rate)
• Automatic power-fail detect and switch circuitry for seamless transition to backup supply
• Programmable square-wave output signal selectable at 1Hz, 4kHz, 8kHz, or 32kHz

Real Time Clock Applications

• Data logging systems requiring precise timestamping
• Industrial control equipment operating in wide temperature environments
• Battery-powered devices needing persistent timekeeping during power loss
• Embedded microcontroller systems utilizing I2C communication protocols

Real Time Clock Procurement Notes

Verify that the specific order suffix matches the required package type and temperature rating. The 'ZN+' designation indicates an 8-pin SOIC package with an industrial temperature range (-40°C to +85°C). Confirm RoHS compliance status as indicated by the '+' suffix. Ensure availability aligns with restricted supply conditions if applicable. Cross-reference the manufacturer part number with distributor listings to confirm exact physical dimensions and pinout compatibility before procurement.

Real Time Clock Selection Notes

Select the DS1307ZN+ when an industrial temperature range is required alongside surface-mount packaging. This variant differs from the commercial grade DS1307Z+ which is limited to 0°C to +70°C. Ensure the design accommodates the 4.5V to 5.5V VCC supply range and provides a 2.0V to 3.5V backup voltage source on the VBAT pin. External pull-up resistors are mandatory for SDA, SCL, and SQW/OUT lines. Verify that the system does not require fast-mode (400kHz) I2C operation, as this device supports only standard mode.

Real Time Clock Part Context

The DS1307ZN+ belongs to the DS1307 family of serial real-time clocks produced by Maxim Integrated, now part of Analog Devices. It serves as a successor to earlier Dallas Semiconductor RTC designs, offering enhanced integration in an 8-pin SOIC package. The 'N' suffix specifically denotes the industrial temperature extension compared to the standard commercial variants. This component is widely recognized for its simplicity in interfacing with microcontrollers via the I2C protocol while providing reliable timekeeping functions.

Real Time Clock Replacement Considerations

Public confirmed substitute part numbers: DS1307ZN+T&R (Tape and Reel version of the same component).

Real Time Clock FAQ

What is the default state of the oscillator upon initial power application?

Upon first application of power, the Clock Halt (CH) bit in the seconds register is typically set to 1, disabling the oscillator. The user must clear this bit to enable timekeeping.

How does the DS1307 handle month length variations?

The device automatically adjusts the date for months with fewer than 31 days. It also includes corrections for leap years, ensuring accurate date tracking up to the year 2100 without software intervention.

What is the maximum I2C clock frequency supported by this device?

The DS1307 operates exclusively in standard mode, supporting a maximum SCL clock frequency of 100 kHz. It does not support fast mode (400 kHz).