DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs

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ORDERING INFORMATION

PART

VOLTAGE

(V)

TEMP RANGE

PIN-PACKAGE

TOP MARK**

DS1744-70+

5.0

0°C to +70°C

28 EDIP

DS1744+70

DS1744-70IND+

5.0

-40°C to +85°C

28 EDIP

DS1744+70 IND

DS1744W-120+

3.3

0°C to +70°C

28 EDIP

DS1744W+120

DS1744W-120IND+

3.3

-40°C to +85°C

28 EDIP

DS1744W+120 IND

DS1744P-70+

5.0

0°C to +70°C

34 PowerCap*

DS1744P+70

DS1744P-70IND+

5.0

-40°C to +85°C

34 PowerCap*

DS1744P+70 IND

DS1744WP-120+

3.3

0°C to +70°C

34 PowerCap*

DS1744WP+120

DS1744WP-120IND+

3.3

-40°C to +85°C

34 PowerCap*

DS1744WP+120 IND

+Denotes a lead(Pb)-free/RoHS-compliant package.

*DS9034-PCX+ or DS9034I-PCX+ required (must be ordered separately).

**A “+” anywhere in the top mark denotes a lead-free device. An “IND” denotes an industrial temperature grade device.

DESCRIPTION

The DS1744 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and 32k x 8

NV SRAM. User access to all registers within the DS1744 is accomplished with a byte-wide interface as

shown in Figure 1. The RTC information and control bits reside in the eight uppermost RAM locations.

The RTC registers contain century, year, month, date, day, hours, minutes, and seconds data in 24-hour

BCD format. Corrections for the date of each month and leap year are made automatically. The RTC clock

registers are double-buffered to avoid access of incorrect data that can occur during clock update cycles.

The double-buffered system also prevents time loss as the timekeeping countdown continues unabated by

access to time register data. The DS1744 also contains its own power-fail circuitry that deselects the