DS12885S+

Overview

The DS12885S+ is a real-time clock (RTC) and calendar integrated circuit manufactured by Analog Devices Inc./Maxim Integrated. It provides timekeeping for seconds, minutes, hours, day, date, month, and year with leap year compensation through 2099. The device features 114 bytes of battery-backed static RAM and supports both Intel and Motorola bus timing modes via a multiplexed byte-wide interface. It operates on a primary supply voltage of 4.5V to 5.5V and includes automatic power-fail detection and switching to a backup supply connected to the VBAT pin.

Feature Summary

• Drop-in replacement for IBM AT computer clock/calendar
• 114 bytes of general-purpose, battery-backed NVSRAM
• Automatic power-fail detect and switch circuitry
• Selectable Intel or Motorola bus timing

Applications

• Embedded Systems
• Utility Meters
• Security Systems
• Network Hubs, Bridges, and Routers

Procurement Notes

Verify the package type matches the required form factor, as the DS12885 family is available in multiple packages including SOIC, PLCC, TQFP, and EDIP. Confirm that the specific suffix indicates the correct temperature range and packaging style intended for the design. Ensure the ordering information aligns with the selected bus timing mode requirements.

Selection Notes

Select this component when a direct replacement for legacy IBM AT RTC functionality is required. Ensure the system design accommodates the 4.5V to 5.5V primary supply voltage range. Verify that the external crystal meets the specified load capacitance of 6pF for accurate oscillator operation. Consider the interrupt and alarm requirements against the available maskable flags.

Part Context

The DS12885 is part of a family of real-time clocks designed as direct replacements for the earlier DS1285 and DS1287 models. It shares functional similarities with the DS12887 and DS12C887, differing primarily in package options and the inclusion of a century byte in specific variants. The S+ suffix denotes the surface-mount SOIC package variant within this product line.

Replacement Considerations

DS12885T+