DS12885QN+T&R

Overview

The DS12885QN+T&R is a real-time clock and calendar IC in a 28-PLCC surface-mount package. It provides timekeeping with binary or BCD formats, automatic leap year correction through 2099, and daylight saving time options. The device includes 114 bytes of battery-backed static RAM and supports multiplexed parallel interfaces compatible with Intel and Motorola bus timing. Primary power operates between 4.5V and 5.5V, while the backup supply accepts 2.5V to 4V. It features an industrial temperature range from -40°C to +85°C.

Feature Summary

• Real-time clock/calendar with automatic date adjustment for months and leap years through 2099
• 114 bytes of nonvolatile, battery-backed static RAM accessible via multiplexed byte-wide interface
• Supports both Intel and Motorola bus timing modes with selectable data representation (Binary or BCD)
• Includes one time-of-day alarm, three maskable interrupts, and a programmable square-wave output

Applications

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

Procurement Notes

Verify the specific ordering suffix 'T&R' corresponds to the Tape & Reel packaging format as indicated in local product fields. Confirm that the industrial temperature grade (-40°C to +85°C) matches the system requirements, as commercial variants exist within the same family. Ensure the VBAT input is connected to a lithium coin-cell battery or grounded if backup is not utilized, adhering to the specified voltage limits.

Selection Notes

Select this component when a drop-in replacement for IBM AT computer clock circuits is required. Choose the DS12885QN+T&R over the DS12C887 variants if a century byte at address 32h is not needed, as the DS12885 uses that address for general-purpose RAM. Ensure the design accommodates the external 32.768kHz crystal connection on pins X1 and X2, as the oscillator circuitry does not include an integrated crystal source unlike the DS12887 series.

Part Context

The DS12885 is part of a family designed as direct replacements for legacy DS1285 and DS1287 devices. While the DS12887 integrates a quartz crystal and lithium energy source into a DIP package, the DS12885 requires external components for these functions. The QN suffix denotes the industrial temperature range and PLCC package, while T&R specifies the reel packaging for automated assembly.

Replacement Considerations

DS12885T+