DS1554W-120IND+

Real Time Clock Overview

The DS1554W-120IND+ is a Y2K-compliant real-time clock and 32k x 8 nonvolatile static RAM integrated into a single 32-pin encapsulated DIP module. Operating at 3.3V with an access time of 120ns, it features a parallel interface for direct CPU access to RTC registers located in the top 16 memory locations. The device includes an internal lithium battery that maintains data retention for over 10 years without power. It supports BCD-coded timekeeping with automatic leap-year compensation up to 2100, programmable alarms, watchdog timers, and power-fail write protection.

Real Time Clock Feature Summary

• Integrated NV SRAM (32k x 8), RTC, crystal, and lithium energy source in one package
• Y2K-compliant with automatic leap-year compensation valid through 2100
• Programmable watchdog timer and alarm with interrupt output
• Power-fail write protection ensures data integrity during voltage drops

Real Time Clock Applications

• Industrial systems requiring nonvolatile timekeeping and data storage
• Embedded controllers needing backup RAM and calendar functions
• Battery-powered devices requiring low standby current and long life expectancy

Real Time Clock Procurement Notes

Verify the specific ordering suffix against the manufacturer's current documentation to confirm lead-free status and temperature grade. Confirm package type compatibility, as this model uses a 32-pin EDIP format distinct from PowerCap variants. Ensure supply chain sources provide original manufacturer documentation for accuracy.

Real Time Clock Selection Notes

Select the DS1554W-120IND+ for applications requiring 3.3V operation and industrial temperature range (-40°C to +85°C). Compare with the 5V DS1554-70IND+ if system voltage differs. Consider the PowerCap variant only if surface-mount assembly constraints require separate battery mounting after reflow.

Real Time Clock Part Context

This component belongs to the Maxim Integrated DS1554 family of nonvolatile timekeeping RAMs. It combines standard SRAM functionality with precise clock/calendar capabilities. The 'W' suffix indicates 3.3V operation, while 'IND' denotes the industrial temperature range. It serves as a complete solution for systems needing persistent time and data storage without external components.

Real Time Clock Replacement Considerations

Direct replacements include other DS1554 variants with matching voltage and temperature ratings, such as the DS1554W-120+ for commercial temperature range. Cross-model substitutes like the DS1251 or DS1556 offer similar NVSRAM and RTC functions but may differ in pinout, capacity, or interface requirements.