DS1746W-120+

Real Time Clock Overview

The DS1746W-120+ is a Y2K-compliant, nonvolatile timekeeping RAM integrating a real-time clock/calendar and 128k x 8 static RAM. Operating at 3.3V with a supply range of 2.97V to 3.63V, it features BCD-coded registers for century, year, month, date, day, hours, minutes, and seconds, including automatic leap year compensation valid until 2100. The device utilizes a standard JEDEC byte-wide interface where clock registers reside in the eight top RAM locations. It includes integrated power-fail write protection, a lithium energy source, and a crystal, housed in a 32-pin encapsulated DIP module.

Real Time Clock Feature Summary

• Integrates NV SRAM, RTC, crystal, power-fail control circuit, and lithium battery in one package
• Y2K compliant with BCD-coded registers and automatic leap year compensation valid to 2100
• Totally nonvolatile with over 10 years of operation without power
• Power-fail write protection allows ±10% VCC supply tolerance

Real Time Clock Applications

• Systems requiring precise timekeeping and data retention during power outages
• Industrial equipment needing Y2K compliance and long-term battery backup
• Embedded controllers utilizing standard static RAM interfaces for clock access

Real Time Clock Procurement Notes

Verify the specific voltage rating (3.3V) and temperature grade (Commercial 0°C to +70°C) against system requirements. Confirm the 32-pin EDIP package format matches the PCB footprint. Ensure the ordering suffix indicates lead-free/RoHS compliance if required by environmental regulations.

Real Time Clock Selection Notes

Select this component when a combined RTC and large NVSRAM solution is needed in a through-hole DIP package. Compare against the DS1746-70+ variant if a 5V supply is available instead of 3.3V. Consider the PowerCap version only if surface mount assembly is strictly required, as the W suffix denotes the encapsulated DIP module.

Real Time Clock Part Context

This part belongs to the Maxim Integrated DS174xP family of timekeeping RAMs. It shares pinout compatibility with other densities in the series, such as the DS1743 and DS1746-70 variants. The 'W' designation specifically identifies the encapsulated DIP module containing the internal battery and crystal, distinct from the separate PowerCap board configuration.

Real Time Clock Replacement Considerations

The DS1746-70IND+ serves as a direct replacement if the application supports a 5V supply instead of 3.3V. Verify that the higher operating voltage does not conflict with existing logic levels or power rails before substitution.