
AD9731
–5–
REV. A
PIN FUNCTION DESCRIPTION
Pin #
Pin Name
Pin Description
1
2–9
10
11
12, 13
14
15, 18, 28
16
17
D9(MSB)
D8–D1
D0(LSB)
CLOCK
NC
DIGITAL +V
S
GND
DIGITAL –V
S
R
SET
Most significant data bit of digital input word.
Eight bits of 10-bit digital input word.
Least significant data bit of digital input word.
TTL-compatible edge-triggered latch enable signal for on-board registers.
No internal connection to this pin.
+5 V supply voltage for digital circuitry.
Converter Ground.
–5.2 V supply voltage for digital circuitry.
Connection for external reference set resistor; nominal 1.96 k
. Full-scale output current =
32 (Control Amp in V/R
SET
).
Analog Return. This point and the reference side of the DAC load resistors should be con-
nected to the same potential (nominally ground).
Analog current output; full-scale current occurs with a digital word input of all “1s.” With
external load resistor, output voltage = I
OUT
(R
LOAD
i
R
INTERNAL
). R
INTERNAL
is nominally
240
.
Complementary analog current output; full-scale current occurs with a digital word input
of all “0s.”
Negative analog supply, nominally –5.2 V.
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
output current of the DAC. Full-scale current output = 32 (CONTROL AMP IN/R
SET
)
when using the internal amplifier. DAC load is virtual ground.
Normally connected to REF IN (Pin 23). Output of internal control amplifier which pro-
vides a reference for the current switch network.
Normally connected to CONTROL AMP IN (Pin 26). Internal voltage reference, nomi-
nally –1.25 V.
Normally connected to REF Out (Pin 25) if not connected to external reference.
Negative digital supply, nominally –5.2 V.
19
ANALOG RETURN
20
I
OUT
21
I
OUTB
22
23
ANALOG –V
S
REF IN
24
CONTROL AMP OUT
25
REF OUT
26
27
CONTROL AMP IN
DIGITAL –V
S
PIN CONFIGURATION
GND
DIGITAL –V
S
CONTROL AMP IN
REF OUT
CONTROL AMP OUT
REF IN
ANALOG –V
S
I
OUTB
I
OUT
ANALOG RETURN
GND
R
SET
DIGITAL –V
S
GND
D8
D7
D9(MSB)
D6
D5
D4
D3
D2
D1
D0(LSB)
CLOCK
NC
NC
DIGITAL +V
S
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