DS1554W-120

Real Time Clock Overview

The DS1554W-120 is a nonvolatile, Y2K-compliant timekeeping RAM device integrating a real-time clock (RTC), 32k x 8 static RAM, crystal, and lithium energy source. It operates at 3.3V with a parallel interface in a 32-pin EDIP package. The RTC provides century, year, month, date, day, hours, minutes, and seconds data in BCD format with automatic leap-year compensation valid to 2100. Key features include a programmable watchdog timer, alarm function, power-fail write protection, and battery voltage-level indicator. Data retention exceeds 10 years without power.

Real Time Clock Feature Summary

• Integrated 32k x 8 Nonvolatile SRAM with RTC registers mapped to the top 16 RAM locations
• Y2K-compliant RTC with automatic leap-year compensation and BCD-coded time/date registers
• Programmable watchdog timer and alarm with interrupt output (IRQ/FT)
• Power-fail write protection and precision power-on reset (RST) circuitry

Real Time Clock Applications

• Industrial control systems requiring precise timekeeping and data retention
• Embedded systems needing nonvolatile memory with integrated clock functionality
• Battery-backed backup solutions for critical system data logging

Real Time Clock Procurement Notes

Verify the specific suffix W-120 indicates the 3.3V commercial temperature grade variant. Confirm package type is 32-pin EDIP. Check for lead-free compliance (+ suffix). Ensure compatibility with existing parallel bus interfaces and address decoding logic. Review datasheet for errata related to specific manufacturing revisions.

Real Time Clock Selection Notes

Select this part when a combined RTC and large nonvolatile RAM solution is required in a single component. The 3.3V operating voltage distinguishes it from the 5V DS1554 variants. The EDIP package integrates the crystal and battery, simplifying board layout compared to PowerCap modules. Consider industrial temperature range (-40°C to +85°C) if environmental conditions require the IND suffix.

Real Time Clock Part Context

The DS1554 series includes 5V and 3.3V variants. The DS1554W-120 specifically denotes the 3.3V version in the commercial temperature range (0°C to +70°C). Other variants include DS1554-70+ (5V) and DS1554W-120IND+ (3.3V industrial). The PowerCap module option (DS1554WP) separates the battery/crystal into a separate component.

Real Time Clock Replacement Considerations

Direct pin-compatible replacements within the same family include DS1554W-120IND+ for industrial temperature operation. For 5V systems, DS1554-70+ or DS1554-70IND+ are electrically similar but require different supply voltages. No cross-family direct replacements are confirmed in the provided documentation.