DS12885Q+T&R

Overview

The DS12885Q+T&R is a real-time clock and calendar IC in a 28-PLCC surface-mount package. It provides timekeeping for seconds, minutes, hours, day, date, month, and year with automatic leap-year compensation through 2099. The device includes 114 bytes of battery-backed static RAM and supports both Intel and Motorola multiplexed bus interfaces. Primary power operates between 4.5V and 5.5V, while the backup supply accepts 2.5V to 4V. Maximum current consumption during active timing is 15mA at 4.5V–5.5V. The component functions within a commercial temperature range of 0°C to 70°C.

Feature Summary

• Direct drop-in replacement for IBM AT computer clock/calendar systems
• 114 bytes of nonvolatile, battery-backed static RAM
• Multiplexed byte-wide interface supporting Intel and Motorola modes
• Automatic power-fail detection and switching circuitry

Applications

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

Procurement Notes

Verify the specific suffix 'T&R' indicates Tape & Reel packaging when sourcing. Confirm the operating temperature grade matches the application requirements, as industrial variants (-40°C to +85°C) exist under different suffixes. Ensure the VBAT pin is connected to a lithium coin-cell or grounded if backup is not utilized. Check for end-of-life status on distributor platforms before finalizing procurement plans.

Selection Notes

Select this component for designs requiring parallel interface compatibility with legacy IBM AT architectures. Choose the Q variant for surface-mount PLCC packaging needs. Verify that the system can provide a stable 32.768kHz crystal load capacitance of 6pF. Consider the DS12C887 if a century byte at address 32h is required instead of general-purpose RAM.

Part Context

This part belongs to the DS12885 family, which also includes the DS12887 (integrated crystal/battery in DIP) and DS12C887 (adds century byte). The DS12885 serves as a direct functional replacement for the older DS1285 and DS1287 models. The manufacturer is Analog Devices Inc./Maxim Integrated.

Replacement Considerations

Public confirmed substitute part numbers are not available in the provided documentation.