AD9731

–5–

REV. A

PIN FUNCTION DESCRIPTION

Pin #

Pin Name

Pin Description

1

D9(MSB)

Most significant data bit of digital input word.

2–9

D8–D1

Eight bits of 10-bit digital input word.

10

D0(LSB)

Least significant data bit of digital input word.

11

CLOCK

TTL-compatible edge-triggered latch enable signal for on-board registers.

12, 13

NC

No internal connection to this pin.

14

+5 V supply voltage for digital circuitry.

15, 18, 28

GND

Converter Ground.

16

–5.2 V supply voltage for digital circuitry.

17

Connection for external reference set resistor; nominal 1.96 k

Ω. Full-scale output current =

19

ANALOG RETURN

Analog Return. This point and the reference side of the DAC load resistors should be con-

nected to the same potential (nominally ground).

20

Analog current output; full-scale current occurs with a digital word input of all “1s.” With

240

Ω.

21

Complementary analog current output; full-scale current occurs with a digital word input

of all “0s.”

22

Negative analog supply, nominally –5.2 V.

23

REF IN

Normally connected to CONTROL AMP OUT (Pin 24). Direct line to DAC current

source network. Voltage changes (noise) at this point have a direct effect on the full-scale

when using the internal amplifier. DAC load is virtual ground.

24

CONTROL AMP OUT

Normally connected to REF IN (Pin 23). Output of internal control amplifier which pro-

vides a reference for the current switch network.

25

REF OUT

Normally connected to CONTROL AMP IN (Pin 26). Internal voltage reference, nomi-

nally –1.25 V.

26

CONTROL AMP IN

Normally connected to REF Out (Pin 25) if not connected to external reference.

27

Negative digital supply, nominally –5.2 V.

PIN CONFIGURATION

GND

CONTROL AMP IN

REF OUT

CONTROL AMP OUT

REF IN

ANALOG RETURN

GND

GND

D8

D7

D9(MSB)

D6

D5

D4

D3

D2

D1

D0(LSB)

CLOCK

NC

NC

TOP VIEW

(Not to Scale)

28

27

26

25

24

23

22

21

20

19

18

17

16

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

AD9731

NC = NO CONNECT