DS1556W-120IND+

Real Time Clock Overview

The DS1556W-120IND+ is a Y2K-compliant real-time clock/calendar integrated with 128KB nonvolatile static RAM. It operates on a 3.3V supply within an industrial temperature range of -40°C to +85°C. The device features a parallel interface, 32-pin EDIP package, and includes an internal lithium battery for over 10 years of data retention without power. Key functions include programmable alarms, watchdog timers, and automatic leap-year compensation.

Real Time Clock Feature Summary

• Integrated RTC with 128KB NV SRAM and internal lithium energy source
• Y2K-compliant BCD-coded calendar with automatic leap-year correction
• Programmable alarm and watchdog timer with interrupt/reset outputs
• Power-fail write protection and precision power-on reset

Real Time Clock Applications

• Industrial systems requiring precise timekeeping during power outages
• Data logging equipment needing nonvolatile storage for timestamps
• Embedded controllers utilizing watchdog timer functionality for system stability

Real Time Clock Procurement Notes

Verify the specific suffix IND+ confirms the industrial temperature grade (-40°C to +85°C) and lead-free/RoHS compliance. Confirm the W suffix indicates the 32-pin EDIP package variant suitable for through-hole mounting. Ensure the 3.3V operating voltage matches the target system design requirements.

Real Time Clock Selection Notes

Select this component when a combined RTC and substantial nonvolatile memory buffer is required in a single package. The 128KB capacity supports extensive data logging alongside timekeeping. The parallel interface requires sufficient address and data lines from the host microcontroller. Consider the PowerCap module alternative if surface-mount assembly constraints apply.

Real Time Clock Part Context

This part belongs to the Maxim Integrated DS1556 family of 1M nonvolatile timekeeping RAMs. The 'W' designation specifies the 3.3V version housed in a 32-pin encapsulated DIP module. The 'IND' suffix denotes the extended industrial temperature rating, distinguishing it from commercial grade variants.

Real Time Clock Replacement Considerations

Direct replacements within the same family include the DS1556P-120IND+ (PowerCap package) or the DS1556-120IND+ (5V version). Verify pin compatibility and voltage levels before substituting. Cross-family RTCs require significant interface redesign due to differing communication protocols.