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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 70ns 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 ±10%

 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

 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

PIN CONFIGURATIONS

ORDERING INFORMATION

PART

VOLTAGE RANGE

(V)

TEMP RANGE

PIN-PACKAGE

TOP MARK

DS1643-70+

5.0

0°C to +70°C

28 EDIP (0.740)

DS1643+70

DS1643-70

5.0

0°C to +70°C

28 EDIP (0.740)

DS1643-70

DS1643-100+

5.0

0°C to +70°C

28 EDIP (0.740)

DS1643+100

DS1643-100

5.0

0°C to +70°C

28 EDIP (0.740)

DS1643-100

DS1643P-70+

5.0

0°C to +70°C

34-PowerCap*

DS1643P+70

DS1643P-70

5.0

0°C to +70°C

34-PowerCap*

DS1643P-70

DS1643P-100+

5.0

0°C to +70°C

34-PowerCap*

DS1643P+100

DS1643P-100

5.0

0°C to +70°C

34-PowerCap*

DS1643P-100

+Denotes a lead(Pb)-free/RoHS-compliant packaget. The top mark will include a “+” symbol on lead-free devices.

DS1643/DS1643P

Nonvolatile Timekeeping RAMs

www.maxim-ic.com

13

27

Encapsulated DIP

(700-mil Extended)

A7

A5

A3

A2

A1

A0

DQ0

DQ1

GND

DQ2

WE

CE2

A8

A9

A11

OE

A10

CE

DQ7

DQ6

DQ5

DQ3

DQ4

1

2

3

4

5

6

7

8

9

10

11

12

14

28

26

25

24

23

22

21

20

19

18

17

15

16

A12

A6

A4

N.C.

DS1643

1

N.C.

2

3

N.C.

N.C.

PFO

WE

OE

CE

DQ7

DQ6

DQ5

DQ4

DQ3

DQ2

DQ1

DQ0

GND

4

5

6

7

8

9

10

11

12

13

14

15

16

17

N.C.

N.C.

33

32

31

30

29

28

27

26

25

24

23

22

21

20

19

18

N.C.

A12

A11

A10

A9

A8

A7

A6

A5

A4

A3

A2

A1

A0

34

N.C.

X1

X2

PowerCap Module Board

(Uses DS9034PCX PowerCap)

DS1643P

TOP VIEW

19-5058; Rev 12/09