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DESCRIPTION

The DS1643 is an 8K x 8 nonvolatile static RAM with a full function Real Time Clock (RTC) that are both accessible in a byte-wide format. The nonvolatile timekeeping RAM is functionally equivalent to any JEDEC standard 8K x 8 SRAM. The device can also be easily substituted in ROM, EPROM and EEPROM sockets providing read/write nonvolatility and the addition of the real time clock function. The real time clock information resides in the eightuppermost RAM locations.

FEATURES

Integrated NV SRAM, Real-Time Clock,? Crystal, Power-Fail Control Circuit and Lithium Energy Source

Clock Registers are Accessed Identically to the Static RAM. These Registers Reside in the Eight Top RAM? Locations.

Totally Nonvolatile with Over 10 Years of Operation in the Absence of Power

Access Times of 85ns and 100ns

BCD-Coded Year, Month, Date, Day, Hours, Minutes, and Seconds with Leap Year Compensation Valid Up to 2100

Power-Fail Write Protection Allows for ¡À10 VCCPower Supply Tolerance

Lithium Energy Source is Electrically

Disconnected to Retain Freshness Until Power is Applied for the First Time

DS1643 Only (DIP Module)

? Standard JEDEC Byte-Wide 8K x 8 RAM Pinout

UL Recognized

DS1643P Only (PowerCap Module Board) Surface Mountable Package for Direct Connection to PowerCap Containing Battery and Crystal Replaceable Battery (PowerCap) Power-Fail Output

Pin-for-Pin Compatible with Other Densities of

DS164XP Timekeeping RAM