AD871

REV. A

–5–

PIN FUNCTION DESCRIPTIONS

DIP

LCC

Symbol

Pin No.

Pin No.

Type

Name and Function

1

1

AI

(+) Analog Input Signal on the differential input amplifier.

2

2

AI

(–) Analog Input Signal on the differential input amplifier.

3, 25

5, 40

P

–5 V Analog Supply.

4

6, 38

P

+5 V Analog Supply.

AGND

5, 24

9, 36

P

Analog Ground.

DGND

6, 23

10

P

Digital Ground.

7, 22

33

P

+5 V Digital Supply.

BIT 12 (LSB)

8

16

DO

Least Significant Bit.

BIT 2–BIT 11

18–9

26–17

DO

Data Bits 2 through 11.

MSB

19

29

DO

Inverted Most Significant Bit. Provides twos complement output

data format.

OTR

20

30

DO

Out of Range is Active HIGH on the leading edge of code 0 or

the trailing edge of code 4096. See Output Data Format Table III.

CLK

21

31

DI

Clock Input. The AD871 will initiate a conversion on the rising

edge of the clock input. See the Timing Diagram for details.

REF OUT

26

41

AO

+2.5 V Reference Output. Tie to REF IN for normal operation.

REF GND

27

42

AI

Reference Ground.

REF IN

28

43

AI

Reference Input. +2.5 V input gives

±1 V full-scale range.

BIT 1 (MSB)

N/A

27

DO

Most Significant Bit.

N/A

12, 32

P

+5 V Digital Supply for the output drivers.

DRGND

N/A

11, 34

P

Digital Ground for the output drivers.

(See section on Power Supply Decoupling for details on

OEN

N/A

13

DI

Output Enable. See the Three State Output Timing Diagram for details.

NC

N/A

3, 4, 7, 8, 14, 15,

No Connect.

28, 35, 37, 39, 44

TYPE: AI = Analog Input; AO = Analog Output; DI = Digital Input; DO = Digital Output; P = Power; N/A = Not Available on 28-lead DIP, available only on

44-terminal surface mount package.

PIN CONFIGURATIONS

28-Lead Side Brazed Ceramic DIP

TOP VIEW

(Not to Scale)

AD871

BIT 11

BIT 12 (LSB)

DGND

AGND

OTR

CLK

REF IN

REF GND

REF OUT

AGND

MSB

BIT 10

BIT 9

BIT 8

BIT 7

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

DGND

44-Terminal LCC

39

38

37

36

35

34

33

32

31

30

29

18 19 20 21 22 23 24 25 26 27 28

7

8

9

10

11

12

13

14

15

16

17

6

5

4

3

2

1

44 43 42 41 40

PIN 1

IDENTIFIER

TOP VIEW

(Not to Scale)

NC = NO CONNECT

NC

NC

AGND

NC

DRGND

CLK

OTR

MSB

NC

NC

AGND

DGND

DRGND

OEN

NC

NC

BIT 12 (LSB)

BIT 11

AD871