DS17285S-3+

Real Time Clock Overview

The DS17285S-3+ is a real-time clock (RTC) IC from Analog Devices/Maxim Integrated, designed as a successor to the DS12885. It provides timekeeping with calendar functions including leap year compensation through 2099. The device features a multiplexed byte-wide interface and includes 2KB of battery-backed NV SRAM alongside standard 114 bytes of general-purpose RAM. It operates within a supply voltage range of 2.7V to 3.7V and supports both 12-hour and 24-hour time formats. Key capabilities include power-fail detection, automatic switching to backup supplies, and system power-on control via alarm or kickstart inputs.

Real Time Clock Feature Summary

• Integrated 2KB battery-backed NV SRAM for extended data storage
• Multiplexed address/data bus interface for direct processor connection
• Automatic power-fail detection with seamless switch to VBAT/VBAUX
• System power-on capability triggered by date/time alarm or key closure

Real Time Clock Applications

• Embedded systems requiring precise timekeeping
• Utility meters for billing and monitoring
• Security systems needing event logging
• Network hubs, bridges, and routers

Real Time Clock Procurement Notes

Verify that the specific ordering suffix '-3+' corresponds to the +3.0V operation variant. Confirm package availability in SO-24 format. Check for RoHS compliance status and lead times directly with authorized distributors or the manufacturer, as stock levels may vary.

Real Time Clock Selection Notes

Select this component when a multiplexed parallel interface is required instead of serial protocols like I2C or SPI. Ensure the system design accommodates the 2.7V to 3.7V VCC range. Consider the need for external crystal selection based on load capacitance requirements (6pF or 12.5pF). Verify that the 2KB NV SRAM meets the nonvolatile memory capacity needs.

Real Time Clock Part Context

This part belongs to the DS17x85 family, which also includes variants with 4KB and 8KB NV SRAM capacities. It serves as an enhanced replacement for the legacy DS12885 series, offering additional features such as a silicon serial number and improved power control circuitry while maintaining pin compatibility.

Real Time Clock Replacement Considerations

Direct replacements within the same family include DS17485S-3+ (4KB NV SRAM) and DS17885S-3+ (8KB NV SRAM), provided the increased memory is acceptable. Legacy equivalents like the DS12885S+ offer similar functionality but lack the extended NV SRAM and modern power management features.