DS1747-70+

Real Time Clock Overview

The DS1747-70+ is a Y2K-compliant real-time clock/calendar and 512k x 8 nonvolatile static RAM. It integrates the RTC, crystal, lithium energy source, and power-fail control circuit within a single package. The device operates at a supply voltage of 5.0V with an operating temperature range of 0°C to +70°C. It utilizes a standard JEDEC byte-wide parallel interface for access. The RTC registers are double-buffered and reside in the eight uppermost RAM locations, storing century, year, month, date, day, hours, minutes, and seconds in BCD format. Data retention exceeds 10 years without power.

Real Time Clock Feature Summary

• Integrated NV SRAM, Real-Time Clock (RTC), Crystal, Power-Fail Control Circuit, and Lithium Energy Source
• Y2K Compliant Century Byte Register with Automatic Leap Year Compensation Valid Up to the Year 2100
• Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power
• Standard JEDEC Byte-Wide 512k x 8 Static RAM Pinout

Real Time Clock Applications

• Systems requiring Y2K-compliant timekeeping and nonvolatile data storage
• Industrial equipment needing integrated battery backup and RTC functionality
• Embedded systems utilizing standard parallel SRAM interfaces for clock and calendar operations

Real Time Clock Procurement Notes

Verify the specific suffix 'IND' if industrial temperature operation (-40°C to +85°C) is required, as the DS1747-70+ is rated for commercial temperatures (0°C to +70°C). Confirm that the 32-pin EDIP package aligns with the target PCB layout. Ensure the system design accounts for the separate ordering of the PowerCap module if using the surface-mount variant instead of the encapsulated DIP module.

Real Time Clock Selection Notes

Select the DS1747-70+ when a 5.0V supply is available and commercial temperature range suffices. Choose the DS1747-70IND+ for applications requiring -40°C to +85°C operation. Consider the DS1747P-70+ variant only if surface-mount assembly is necessary, noting that the PowerCap containing the battery and crystal must be ordered separately. Verify compatibility with existing parallel SRAM pinouts.

Real Time Clock Part Context

The DS1747 belongs to the DS174x family of nonvolatile timekeeping RAMs. It is pin-for-pin compatible with other densities in the series, such as the DS1746 and DS1748. The device replaces older discrete RTC and battery backup solutions by integrating all necessary components into a single encapsulated module or board-mounted package.

Real Time Clock Replacement Considerations

The DS1747-70IND+ serves as the direct industrial temperature replacement for the DS1747-70+. For surface-mount requirements, the DS1747P-70+ is the equivalent package type, though it requires a separate PowerCap component.