DS1689

Real Time Clock Overview

The DS1689 is a serialized real-time clock (RTC) IC designed as a successor to the industry-standard DS1287 PC clock. It operates on +3V or +5V supplies and incorporates a unique 64-bit silicon serial number alongside an optional 64-bit customer-specific ROM. The device provides 114 bytes of user non-volatile RAM, automatic battery backup, and write protection for external SRAM via the VCCO pin. Enhanced features include power control circuitry for system wake-up, a century register, and multiple elapsed time counters. It supports multiplexed parallel bus interfaces and includes interrupt capabilities for alarms and periodic events.

Real Time Clock Feature Summary

• Incorporates a unique 64-bit silicon serial number and optional 64-bit customer ROM for electronic identification.
• Provides 114 bytes of general-purpose non-volatile RAM with automatic backup and write protection for external SRAM.
• Supports +3V or +5V operation with autosense voltage detection and auxiliary battery input (VBAUX).
• Features power control circuitry allowing system power-on via date/time alarm or kickstart key closure.

Real Time Clock Applications

• PC motherboard clock/calendar systems requiring BIOS compatibility.
• Industrial data logging applications utilizing NV RAM storage.
• Systems requiring precise timekeeping with leap year compensation valid up to 2100.
• Network node identification using the integrated silicon serial number.

Real Time Clock Procurement Notes

Verify the specific temperature grade and package variant required, such as DS1689S for commercial range or DS1689SN for industrial range. Confirm RoHS compliance status by checking for the '+' suffix in the ordering information. Ensure the design accounts for the multiplexed address/data bus timing requirements during integration.

Real Time Clock Selection Notes

Select the DS1689 when a parallel interface RTC with integrated NV RAM and serial number tracking is needed. Choose the DS1693 module if an embedded battery and crystal are preferred over discrete components. Ensure the application utilizes crystals with specified load capacitances of 6pF or 12.5pF for optimal accuracy. Verify that the external SRAM voltage levels match the VCCO output capabilities.

Real Time Clock Part Context

The DS1689 belongs to the Dallas Semiconductor/Maxim Integrated DS1689/DS1693 family of serialized real-time clocks. It serves as an enhanced replacement for legacy devices like the DS1287, adding serialization and power management features while maintaining register compatibility. The companion part, DS1693, integrates the RTC die with a crystal and battery in a standalone module format.

Real Time Clock Replacement Considerations

The DS1689 is functionally compatible with the DS1287 for standard clock functions. For direct replacements, verify pinout compatibility with other DS128x series variants. No specific cross-model substitutes are listed in the provided documentation beyond the DS1693 module equivalent.