DS1553WP-120

Real Time Clock Overview

The DS1553WP-120 is a Year-2000-compliant real-time clock/calendar with 64KB nonvolatile SRAM. It integrates a lithium battery, crystal, and power-fail control in a 34-pin PowerCap module. Operating at 3.3V ±10%, it supports a commercial temperature range of 0°C to +70°C. The device features a byte-wide parallel interface where RTC registers reside in the top 16 RAM locations (1FF8h–1FFFh). Key functions include an alarm, watchdog timer, power-on reset, and battery monitoring. Data retention exceeds 10 years without power.

Real Time Clock Feature Summary

• Integrated 64KB NV SRAM with RTC registers mapped to addresses 1FF8h–1FFFh
• Year-2000 compliant with automatic leap year compensation valid through 2100
• Programmable watchdog timer and alarm with interrupt output on IRQ/FT pin
• Power-fail write protection and precision power-on reset circuitry

Real Time Clock Applications

• Industrial systems requiring reliable timekeeping and data retention
• Embedded controllers needing CPU watchdog functionality
• Battery-backed memory applications with integrated timing

Real Time Clock Procurement Notes

Verify that the separate DS9034PCX PowerCap module is included, as it contains the required crystal and lithium energy source. Confirm the specific voltage variant matches system requirements, as this model operates at 3.3V. Check for lead-free compliance markings on the package top mark.

Real Time Clock Selection Notes

Select the DS1553WP-120 for 3.3V parallel bus architectures requiring integrated NVSRAM and RTC. Ensure the design accommodates the 34-pin PowerCap footprint and allows post-reflow mounting of the PowerCap module to protect the internal battery from soldering heat. Verify compatibility with the 120ns access time specifications.

Real Time Clock Part Context

This component belongs to the DS1553 family of 64kB Nonvolatile Timekeeping RAMs. Variants differ by supply voltage (3.3V vs 5.0V) and package type (EDIP vs PowerCap). The WP suffix indicates the PowerCap module configuration, while the 120 suffix denotes the 3.3V operating voltage version.

Real Time Clock Replacement Considerations

Direct replacements within the same family include DS1553WP-150+ (same package, different speed grade). For 5V systems, consider DS1553P-85+ or DS1553P-100+. Note that EDIP packages integrate the battery internally, whereas PowerCap requires a separate module.