DS1744/DS1744P Y2K-Compliant, Nonvolatile Timekeeping RAMs

2 of 18

PIN DESCRIPTION

A0–A14

- Address Input

CE

- Chip Enable

OE

- Output Enable

WE

- Write Enable

- Power-Supply Input

GND

- Ground

DQ0–DQ7

- Data Input/Output

N.C.

- No Connection

RST

- Power-On Reset Output (PowerCap module board only)

X1, X2

- Crystal Connection

- Battery Connection

ORDERING INFORMATION

PART

TEMP RANGE

PIN-PACKAGE

VOLTAGE

(V)

TOP MARK

DS1744-70

0°C to +70°C

28 PDIP Module

5

DS1744-70

DS1744-70IND

-40°C to +85°C

28 PDIP Module

5

DS1744-70IND

DS1744P-70

0°C to +70°C

34 PowerCap*

5

DS1744P-70

DS1744P-70IND

-40°C to +85°C

34 PowerCap*

5

DS1744P-70IND

DS1744W-120

0°C to +70°C

28 DIP Module

3.3

DS1744W-120

DS1744W-120IND

-40°C to +85°C

28 DIP Module

3.3

DS1744W-120IND

DS1744WP-120

0°C to +70°C

34 PowerCap*

3.3

DS1744WP-120

DS1744WP-120IND

-40°C to +85°C

34 PowerCap*

3.3

DS1744WP-120IND

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