DS1646-120

Real Time Clock Overview

The DS1646-120+ is a nonvolatile static RAM integrated with a real-time clock, crystal, and lithium energy source. It provides 128k x 8 byte-wide memory accessible via standard JEDEC pinout. The RTC registers occupy the top eight RAM locations, storing year, month, date, day, hours, minutes, and seconds in BCD format with leap year compensation valid to 2100. Operating at 5V ±10%, it features power-fail write protection and CMOS standby current of up to 4mA. Data retention exceeds 10 years without power.

Real Time Clock Feature Summary

• Integrates 128k x 8 NV SRAM, RTC, crystal, and lithium battery in one package
• BCD-coded timekeeping with automatic leap year correction valid through 2100
• Power-fail write protection ensures data integrity during supply voltage drops
• Double-buffered clock registers prevent access errors during internal updates

Real Time Clock Applications

• Systems requiring persistent timekeeping and nonvolatile data storage
• Industrial equipment needing reliable clock/calendar functions
• Embedded controllers replacing ROM/EPROM with read/write nonvolatility

Real Time Clock Procurement Notes

Verify the specific suffix (+) for lead-free/RoHS compliance when ordering. Confirm the package type (32-pin EDIP vs. PowerCap) matches the design requirements. Check manufacturer documentation for exact availability status as distribution may vary.

Real Time Clock Selection Notes

Select the DS1646-120+ for through-hole applications requiring a self-contained RTC module. Ensure the system operates within the 4.5V to 5.5V supply range. Consider the DS1646P variant only if surface-mount assembly with a separate PowerCap module is required.

Real Time Clock Part Context

This component belongs to the DS164x family of nonvolatile timekeeping RAMs. It offers pin-for-pin compatibility with other densities in the series, allowing for density upgrades while maintaining the same interface and form factor.

Real Time Clock Replacement Considerations

Pin-compatible alternatives exist within the DS164x family. Verify that any substitute maintains the 128k x 8 capacity and RTC functionality if these are critical to the application.