DS1746-70

Real Time Clock Overview

The DS1746-70 is a Y2K-compliant, nonvolatile timekeeping RAM integrating a real-time clock/calendar and 128k x 8 static RAM. It features a byte-wide parallel interface where RTC registers occupy the eight topmost memory locations. The device includes an integrated crystal, lithium energy source, and power-fail control circuit within a 32-pin EDIP module. Operating at 5V with a range of 4.5V to 5.5V, it maintains data for over 10 years without power. Key specifications include ±1 minute per month accuracy at 25°C, automatic leap year compensation valid until 2100, and a battery voltage-level indicator flag.

Real Time Clock Feature Summary

• Integrated NV SRAM (128k x 8), Real-Time Clock, Crystal, Power-Fail Control Circuit, and Lithium Energy Source
• Y2K Compliant with BCD-Coded Century, Year, Month, Date, Day, Hours, Minutes, and Seconds
• Automatic Leap Year Compensation Valid Up to the Year 2100
• Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power

Real Time Clock Applications

• Systems requiring Y2K-compliant timekeeping and nonvolatile data storage
• Industrial equipment needing reliable clock/calendar functions with battery backup
• Embedded systems utilizing standard JEDEC byte-wide 128k x 8 Static RAM pinout

Real Time Clock Procurement Notes

Verify component authenticity through authorized distributors or manufacturer channels. Confirm package type matches requirements, as the DS1746-70 is available in a 32-pin EDIP module. Check for lead-free/RoHS compliance markings on the top mark if environmental regulations apply. Ensure proper handling during soldering, as the encapsulated DIP style requires specific thermal profiles to protect the internal lithium energy source.

Real Time Clock Selection Notes

Select the DS1746-70 when a combined RTC and large NV SRAM solution is needed in a single package. Choose this model over the DS1746P variant if through-hole mounting via the 32-pin EDIP module is preferred over surface-mount PowerCap assembly. Verify that the system operates within the 5V supply range and commercial temperature limits (0°C to +70°C). Consider the DS1746-70IND+ if industrial temperature operation (-40°C to +85°C) is required.

Real Time Clock Part Context

The DS1746-70 belongs to the Maxim Integrated DS174x family of nonvolatile timekeeping RAMs. It is pin-for-pin compatible with other densities in the series, such as the DS1743 and DS1745, allowing for density upgrades without redesigning the PCB layout. The device represents a transition from legacy Dallas Semiconductor products to Analog Devices/Maxim Integrated offerings, maintaining functional equivalence while updating manufacturing processes.

Real Time Clock Replacement Considerations

For direct replacements, consider the DS1746-70IND+ for industrial temperature range applications. Surface-mount alternatives include the DS1746P-70+ or DS1746WP-120+ families, which utilize the PowerCap module design. Ensure any substitute maintains the 128k x 8 capacity and parallel interface compatibility.