DS1747/DS1747P Y2K-Compliant, Nonvolatile Timekeeping RAMs

2 of 18

PIN DESCRIPTION

A0–A18

– 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

TOP MARK

DS1747-70

0°C to +70°C

32 EDIP (0.740a)

DS1747-70

DS1747-70IND

-40°C to +85°C

32 EDIP (0.740a)

DS1747-70 IND

DS1747P-70

0°C to +70°C

34 PowerCap

DS1747P-70

DS1747P-70IND

-40°C to +85°C

34 PowerCap

DS1747P-70 IND

DS1747W-120

0°C to +70°C

32 EDIP (0.740a)

DS1747W-120

DS1747W-120IND

-40°C to +85°C

32 EDIP (0.740a)

DS1747W-120 IND

DS1747WP-120

0°C to +70°C

34 PowerCap

DS1747WP-120

DS1747WP-120IND

-40°C to +85°C

34 PowerCap

DS1747WP-120 IND

DESCRIPTION

The DS1747 is a full-function, year-2000-compliant (Y2KC), real-time clock/calendar (RTC) and

512k x 8 nonvolatile static RAM. User access to all registers within the DS1747 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 DS1747 also contains

as errant access and update cycles are avoided.