DS14285SN

Real Time Clock Overview

The DS14285SN is a real-time clock and calendar IC with nonvolatile RAM control, designed as a direct replacement for the IBM AT computer clock. It features a multiplexed bus interface in a 24-pin SOIC package. The device counts seconds, minutes, hours, days, dates, months, and years with leap year compensation valid up to 2100. It includes 114 bytes of general-purpose RAM and 14 bytes of clock/control registers. Operating voltage is 4.5V to 5.5V, with an industrial temperature range of -40°C to +85°C.

Real Time Clock Feature Summary

• Multiplexed address/data bus for pin efficiency
• Automatic backup supply and write protection for external SRAM
• Programmable square-wave output and three software-maskable interrupts
• Daylight saving time option and 12/24-hour clock formats

Real Time Clock Applications

• IBM AT computer clock/calendar replacement
• Systems requiring nonvolatile memory control for external SRAM
• Industrial equipment requiring extended temperature operation

Real Time Clock Procurement Notes

Verify the specific suffix 'SN' confirms the industrial temperature grade (-40°C to +85°C) and SOIC-24 package. Confirm RoHS compliance status based on the presence or absence of the '+' designation in the ordering information. Ensure the source document matches the REV: 112105 datasheet for accurate electrical specifications.

Real Time Clock Selection Notes

Select this component when a functionally compatible successor to the DS1285/DS1287 is required for systems using multiplexed buses. Choose the SN variant over the S variant if operation below 0°C is necessary. Ensure the design accommodates the 5V logic levels and provides an external 32.768 kHz crystal with 6 pF load capacitance.

Real Time Clock Part Context

The DS14285SN belongs to the DS14285/DS14287 family of real-time clocks. It serves as a bridge between legacy IBM AT architecture and modern embedded systems needing battery-backed RAM control. The 'N' suffix denotes the industrial temperature extension, while 'S' indicates the small-outline package.

Real Time Clock Replacement Considerations

The DS17285 series is documented as a functional successor providing enhanced functions like silicon serial numbers and integrated power-on/off control. Verify pin compatibility and register mapping before substituting.