DS12C887

Real Time Clock Overview

The DS12C887 is a Real-Time Clock (RTC) and calendar integrated into a 24-pin EDIP module. It provides timekeeping for seconds, minutes, hours, day of the week, date, month, and year with leap-year compensation through 2099. The device features a multiplexed parallel interface compatible with Intel and Motorola bus protocols. It includes 113 bytes of battery-backed static RAM and an integrated rechargeable lithium battery. Operating at 4.5V to 5.5V, it automatically switches to backup power upon main supply failure.

Real Time Clock Feature Summary

• Integrated 24-EDIP module containing crystal oscillator and rechargeable lithium battery
• Multiplexed parallel interface supporting Intel and Motorola timing modes
• 113-byte battery-backed static RAM for non-volatile data storage
• Automatic power-fail detection and switching circuitry

Real Time Clock Applications

• Embedded systems requiring precise timestamping
• Utility meters and smart grid devices
• Network hubs, bridges, and routers
• Security systems and industrial controllers

Real Time Clock Procurement Notes

Verify the specific manufacturer suffix against official Analog Devices or Maxim Integrated documentation to confirm exact electrical tolerances and package variations. Confirm lead times and availability directly with authorized distributors as stock levels fluctuate. Ensure the 24-EDIP through-hole package matches the target PCB footprint requirements.

Real Time Clock Selection Notes

Select this component when a self-contained RTC solution with integrated power and oscillation is required without external discrete components. The multiplexed parallel interface suits legacy microcontrollers like the 8086 or 8051 families. Verify that the 4.5V to 5.5V supply range aligns with the system voltage rails and that the EDIP package fits the mechanical constraints.

Real Time Clock Part Context

The DS12C887 serves as a direct replacement for the IBM AT computer clock/calendar chips, specifically the DS1285 and MC146818B. It belongs to the DS12887 family, distinguished by the addition of a century byte at address 32h to resolve Y2K issues. This integration simplifies design by combining the RTC logic, memory, and power source into a single DIP-style module.

Real Time Clock Replacement Considerations

Publicly confirmed substitutes include the DS12887 and DS1287. These parts share functional compatibility but may differ in packaging options such as PLCC or TQFP. Verify pinout compatibility and register mapping before substitution.