DS1687-3

Real Time Clock Overview

The DS1687-3+ is a standalone real-time clock (RTC) in a 24-pin EDIP package, integrating the DS1685 chip with an embedded lithium battery and crystal. It operates on a +3V supply (2.7V to 3.7V range) and provides timekeeping through 2099 with leap-year compensation. The device features a multiplexed address/data bus interface, 242 bytes of battery-backed NV SRAM, and a 64-bit silicon serial number. Key capabilities include power-on control via alarm or kickstart, a 32kHz square-wave output, and Y2K compliance.

Real Time Clock Feature Summary

• Integrated EDIP Package: Combines RTC chip, 32.768kHz crystal, and lithium battery for self-contained operation.
• +3V Operation: Designed for 2.7V to 3.7V primary supply with automatic switching to backup sources.
• Multiplexed Interface: Uses AD0-AD7 pins for bidirectional address and data transfer.
• Enhanced Memory: Provides 242 bytes of non-volatile RAM accessible via extended registers.

Real Time Clock Applications

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

Real Time Clock Procurement Notes

Verify the specific ordering suffix (+) confirms lead-free/RoHS compliance as per manufacturer standards. Confirm the -3 variant matches the required 3V operating voltage profile. Check current availability status, as distribution may be restricted in certain regions. Ensure the EDIP form factor fits the target PCB layout constraints.

Real Time Clock Selection Notes

Select the DS1687-3+ when a self-contained RTC solution with integrated power source is required. Choose this over the DS1685 if external crystal and battery components are undesirable. Verify that the system supports the multiplexed bus timing requirements. Ensure the application environment stays within the 0°C to +70°C commercial temperature range.

Real Time Clock Part Context

This component belongs to the DS1685/DS1687 family of 3V/5V Real-Time Clocks. The DS1687 is the encapsulated version of the DS1685 die, featuring built-in energy storage and oscillation components. It serves as a successor to earlier industry-standard PC clocks like the DS1287, offering enhanced features such as silicon serial numbers and advanced power management controls.

Real Time Clock Replacement Considerations

The DS1687-5+ is the direct pin-compatible alternative for systems requiring a +5V supply instead of +3V. For industrial temperature grades (-40°C to +85°C), consider the DS1687-3IND+. The bare die version DS1685 requires external crystal and battery assembly.