DS17885SN-5

Real Time Clock Overview

The DS17885SN-5 is a real-time clock (RTC) and battery-backed NV SRAM device designed as a successor to the industry-standard DS12885. It provides a multiplexed byte-wide interface, a real-time clock/calendar with leap year compensation through 2099, one time-of-day alarm, three maskable interrupts, and a programmable square wave. The device includes 114 bytes of general-purpose battery-backed NV SRAM and 8192 bytes of extended battery-backed NV SRAM. It operates at +5.0V nominal with a range of 4.5V to 5.5V, features automatic power-fail detection and switching, and incorporates a 64-bit silicon serial number.

Real Time Clock Feature Summary

• Incorporates 8192 bytes of extended battery-backed NV SRAM alongside 114 bytes of general-purpose RAM
• Multiplexed address/data bus interface for direct connection to standard PC architectures
• Automatic power-fail detect and switch circuitry with precision temperature-compensated monitoring
• Real-time clock/calendar with leap year correction through 2099 and 12/24-hour format support

Real Time Clock Applications

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

Real Time Clock Procurement Notes

Verify the specific suffix 'SN-5' against official Analog Devices documentation to confirm it denotes the SO-24 package variant operating at the +5V voltage rating. Confirm RoHS compliance status and lead-free manufacturing details directly from the manufacturer's current datasheet revision before procurement.

Real Time Clock Selection Notes

Select this component when an 8KB extended nonvolatile memory capacity is required in addition to standard RTC functions. Ensure the system design supports a multiplexed bus interface and provides a +5V primary supply within the 4.5V to 5.5V operating range. Verify that external crystal load capacitance matches the device's selectable 6pF or 12.5pF settings.

Real Time Clock Part Context

This part belongs to the DS17x85 family, which serves as a modern replacement for the legacy DS12885 series. While maintaining pin compatibility and functional similarities with older standards, the DS17885 adds significant enhanced features such as larger memory arrays, silicon serial numbers, and advanced power-control circuitry for system wake-up capabilities.

Real Time Clock Replacement Considerations

The DS12885SN+ is a compatible predecessor offering similar functionality but with only 114 bytes of NV SRAM instead of 8192 bytes. Designers upgrading from the DS12885 must account for the increased memory map and verify software compatibility with the extended register banks.