DS17885SN-3+

Real Time Clock Overview

The DS17885SN-3+ is a real-time clock (RTC) IC from the DS17x85 family, designed as a successor to industry-standard DS12885/DS12887 devices. It features a multiplexed byte-wide interface and operates with a supply voltage range of 2.7V to 3.7V on VCC. The device integrates a real-time clock/calendar, one time-of-day alarm, three maskable interrupts, a programmable square wave, and 8192 bytes of battery-backed NV SRAM. It includes automatic power-fail detection, leap year compensation through 2099, and a 64-bit silicon serial number. The component is housed in a 24-pin SOIC package.

Real Time Clock Feature Summary

• 8192 Bytes Battery-Backed NV SRAM
• Multiplexed Byte-Wide Interface
• Automatic Power-Fail Detect and Switch Circuitry
• Leap Year Compensation Through 2099
• 64-Bit Silicon Serial Number

Real Time Clock Applications

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

Real Time Clock Procurement Notes

Verify the specific voltage variant suffix '-3+' corresponds to the 2.7V–3.7V operating range required by the design. Confirm package availability for the 24-SOIC form factor. Check current distribution status as legacy RTC components may have limited stock or end-of-life notifications. Ensure backup battery specifications align with the VBAT input requirements.

Real Time Clock Selection Notes

Select this part when an 8KB nonvolatile RAM extension is needed alongside standard RTC functions. The -3+ suffix indicates compatibility with 3V logic systems; verify against the -5+ variant if 5V operation is required. Consider the DS17887 if an integrated crystal and battery are preferred over external components. Ensure the system supports multiplexed address/data bus timing constraints.

Real Time Clock Part Context

This component belongs to the Maxim Integrated DS17x85 series, which serves as a drop-in replacement for the Dallas Semiconductor DS12885/DS12887. The DS17885 specifically offers the largest memory capacity within the base DS17x85 lineup. The SN suffix denotes the Surface Mount SOIC package option, distinct from the PDIP or EDIP variants.

Real Time Clock Replacement Considerations

Direct pin-compatible replacements include the DS12885SN+ (limited to 114 bytes RAM) and the DS17285SN-3+ (2KB RAM). For identical functionality, the DS17885SN-5+ is available for 5V systems. Verify that any substitute maintains the same multiplexed interface timing and interrupt logic.