AD1674
P IN D ESCRIP TIO N
Sym bol
P in No. Type
Nam e and Function
Analog Ground (Common).
AGND
A0
9
4
P
DI
Byte Address/Short Cycle. If a conversion is started with A0 Active LOW, a full 12-bit conversion
cycle is initiated. If A0 is Active HIGH during a convert start, a shorter 8-bit conversion cycle
results. During Read (R/C = 1) with 12/8 LOW, A0 = LOW enables the 8 most significant bits
(DB4–DB11), and A0 = HIGH enables DB3–DB0 and sets DB7–DB4 = 0.
BIP OFF
12
AI
Bipolar Offset. Connect through a 50 Ω resistor to REF OUT for bipolar operation or to Analog
Common for unipolar operation.
CE
6
3
DI
DI
Chip Enable. Chip Enable is Active HIGH and is used to initiate a convert or read operation.
Chip Select. Chip Select is Active LOW.
CS
DB11–DB8 27–24
DO
Data Bits 11 through 8. In the 12-bit format (see 12/8 and A0 pins), these pins provide the up-
per 4 bits of data. In the 8-bit format, they provide the upper 4 bits when A0 is LOW and are
disabled when A0 is HIGH.
DB7–DB4
DB3–DB0
23–20
19–16
DO
DO
Data Bits 7 through 4. In the 12-bit format these pins provide the middle 4 bits of data. In the
8-bit format they provide the middle 4 bits when Ao is LOW and all zeroes when A0 is HIGH.
Data Bits 3 through 0. In the 12-bit format these pins provide the lower 4 bits of data. In the
8-bit format these pins provide the lower 4 bits of data when A0 is HIGH, they are disabled
when A0 is LOW.
DGND
REF OUT
R/C
15
8
P
Digital Ground (Common).
+10 V Reference Output.
AO
DI
5
Read/Convert. In the full control mode R/C is Active HIGH for a read operation and Active LOW
for a convert operation. In the stand-alone mode, the falling edge of R/C initiates a conversion.
REF IN
ST S
10
28
AI
Reference Input is connected through a 50 Ω resistor to +10 V Reference for normal operation.
DO
Status is Active HIGH when a conversion is in progress and goes LOW when the conversion is
completed.
VCC
7
P
+12 V/+15 V Analog Supply.
–12 V/–15 V Analog Supply.
+5 V Logic Supply.
VEE
11
1
P
VLOGIC
10 VIN
P
13
AI
10 V Span Input, 0 V to +10 V unipolar mode or –5 V to +5 V bipolar mode. When using the
AD1674 in the 20 V Span 10 VIN should not be connected.
20 VIN
14
2
AI
20 V Span Input, 0 V to +20 V unipolar mode or –10 V to +10 V bipolar mode. When using
the AD1674 in the 10 V Span 20 VIN should not be connected.
12/8
DI
T he 12/8 pin determines whether the digital output data is to be organized as two 8-bit words
(12/8 LOW) or a single 12-bit word (12/8 HIGH).
T YPE: AI
=
=
=
Analog Input
Analog Output
Digital Input
AO
DI
FUNCTIO NAL BLO CK D IAGRAM
P IN CO NFIGURATIO N
DO = Digital Output
12/8
CS
P
=
Power
V
28
27
26
25
24
23
22
21
20
19
18
17
1
2
3
4
5
6
7
8
9
STS
LOGIC
12/8
STS
DB11(MSB)
DB10
A
CONTROL
0
CS
CE
A
0
DB9
R/C
R/C
CE
DB8
DB7
10V
CLOCK
SAR
REF OUT
AD1674
REF
DB6
V
12
CC
TOP VIEW
REF OUT
AGND
DB5
DB4
(Not to Scale)
DB11 (MSB)
DB0 (LSB)
AGND
COMP
12
20k
REF IN 10
DB3
REF IN
12
V
11
12
13
14
DB2
DB1
5k
10k
10k
EE
BIP OFF
BIP OFF
20V
IN
DAC
16 DB0(LSB)
10V
IN
5k
2.5k
2.5k
20V
IN
15
DGND
10V
IN
IDAC
5k
SHA
AD1674
REV. C
–7–
ADI [ ADI ]
