DS1747W-120+

Real Time Clock Overview

The DS1747W-120+ is a Y2K-compliant, nonvolatile timekeeping RAM integrating a real-time clock/calendar and 512k x 8 static RAM. It operates on a 3.3V supply with an address access time of 120ns. The device features BCD-coded registers for century, year, month, date, day, hours, minutes, and seconds, including automatic leap year compensation valid until 2100. Clock registers are double-buffered to prevent data corruption during updates. It includes power-fail write protection, a battery voltage-level indicator flag, and a lithium energy source that ensures over 10 years of data retention in the absence of VCC.

Real Time Clock Feature Summary

• Integrated NV SRAM (512k x 8), RTC, crystal, and lithium battery in one package
• Y2K compliant with automatic leap year compensation valid through 2100
• Double-buffered clock registers prevent data loss during read cycles
• Power-fail write protection and battery voltage-level indicator flag

Real Time Clock Applications

• Industrial systems requiring long-term nonvolatile timekeeping
• Data logging equipment needing persistent calendar and clock data
• Embedded controllers utilizing standard JEDEC byte-wide RAM pinouts

Real Time Clock Procurement Notes

Verify the specific suffix 'IND' if industrial temperature range (-40°C to +85°C) is required, as the base model DS1747W-120+ specifies commercial range (0°C to +70°C). Confirm RoHS compliance status via the '+' designation. Ensure the application board supports the 32-pin EDIP module form factor and provides appropriate VCC decoupling for stable operation.

Real Time Clock Selection Notes

Select the DS1747W-120+ for 3.3V applications requiring 512KB of nonvolatile memory with integrated timekeeping. Compare against the DS1747-70+ series if a 5.0V supply is available. Consider the PowerCap variant (DS1747P) only if surface-mount assembly followed by separate battery/crystal mounting is necessary to protect components from reflow temperatures.

Real Time Clock Part Context

This component belongs to the DS174x family of Y2K-compliant nonvolatile timekeeping RAMs. It is functionally compatible with other densities in the series, sharing identical register maps for the top eight locations while providing different total RAM capacities. The W suffix denotes the 3.3V operating voltage version within this product line.

Real Time Clock Replacement Considerations

Pin-for-pin compatible with other densities of the DS174xP Timekeeping RAM series. Verify voltage compatibility when substituting with 5V variants like the DS1747-70+.