DS1302

Overview

The DS1302 is a trickle-charge real-time clock (RTC) and calendar IC manufactured by Analog Devices Inc./Maxim Integrated. It provides seconds, minutes, hours, date, month, day of the week, and year information with leap-year compensation valid up to 2100. The device features a simple 3-wire serial interface compatible with most microcontrollers and includes 31 bytes of battery-backed static RAM. Operating on a supply voltage of 2V to 5.5V, it consumes less than 300nA at 2.0V. The specific model DS1302SN+ utilizes an 8-SOIC package and supports an operating temperature range of -40°C to +85°C.

Feature Summary

• Real-time clock/calendar with leap-year compensation valid up to 2100
• 31-byte battery-backed general-purpose RAM
• Simple 3-wire serial interface (CE, I/O, SCLK)
• Low power operation: <300nA at 2.0V

Applications

• Data logging systems requiring precise timestamps
• Portable instruments and handheld devices
• Embedded systems needing persistent timekeeping during power loss

Procurement Notes

Verify the ordering suffix against the datasheet table to confirm the correct package type and temperature grade. The 'N' suffix indicates industrial temperature range (-40°C to +85°C), while absence of 'N' denotes commercial range (0°C to +70°C). Ensure the package variant matches the PCB footprint requirements, as SOIC and DIP versions are distinct.

Selection Notes

Select the DS1302SN+ for applications requiring surface-mount technology and industrial temperature stability. For through-hole designs or commercial temperature ranges, consider the standard DS1302 or DS1302N+. Verify that the host microcontroller can support the synchronous serial protocol timing constraints, specifically the CE setup and hold times relative to the SCLK signal.

Part Context

The DS1302 serves as a successor to the DS1202, adding dual power pins for primary and backup supplies and a programmable trickle charger. It is part of the Maxim Integrated RTC family designed for low-power timekeeping. The SN+ designation specifically identifies the industrial-grade version in the 8-pin Small Outline package.

Replacement Considerations

Direct pin-compatible replacements within the same series include DS1302Z+ (commercial SOIC 150 mil) and DS1302N+ (industrial PDIP). Cross-family replacements like the DS1307 offer I2C interfaces but require schematic and software modifications due to different communication protocols.