AD1674
PIN DESCRIPTION
Symbol
AGND
A
0
Pin No. Type
9
4
P
DI
Name and Function
Analog Ground (Common).
Byte Address/Short Cycle. If a conversion is started with A
0
Active LOW, a full 12-bit conversion
cycle is initiated. If A
0
is Active HIGH during a convert start, a shorter 8-bit conversion cycle
results. During Read (R/C = 1) with 12/8 LOW, A
0
= LOW enables the 8 most significant bits
(DB4–DB11), and A
0
= HIGH enables DB3–DB0 and sets DB7–DB4 = 0.
Bipolar Offset. Connect through a 50
Ω
resistor to REF OUT for bipolar operation or to Analog
Common for unipolar operation.
Chip Enable. Chip Enable is Active HIGH and is used to initiate a convert or read operation.
Chip Select. Chip Select is Active LOW.
Data Bits 11 through 8. In the 12-bit format (see 12/8 and A
0
pins), these pins provide the up-
per 4 bits of data. In the 8-bit format, they provide the upper 4 bits when A
0
is LOW and are
disabled when A
0
is HIGH.
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 A
0
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 A
0
is HIGH, they are disabled
when A
0
is LOW.
Digital Ground (Common).
+10 V Reference Output.
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.
Reference Input is connected through a 50
Ω
resistor to +10 V Reference for normal operation.
Status is Active HIGH when a conversion is in progress and goes LOW when the conversion is
completed.
+12 V/+15 V Analog Supply.
–12 V/–15 V Analog Supply.
+5 V Logic Supply.
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 V
IN
should not be connected.
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 V
IN
should not be connected.
The 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).
FUNCTIONAL BLOCK DIAGRAM
12/8
CS
A
0
CE
R/C
REF OUT
10V
REF
CLOCK
SAR
12
BIP OFF
CE
CS
DB11–DB8
12
6
3
27–24
AI
DI
DI
DO
DB7–DB4
DB3–DB0
23–20
19–16
DO
DO
DGND
REF OUT
R/C
REF IN
STS
V
CC
V
EE
V
LOGIC
10 V
IN
20 V
IN
12/8
TYPE:
AI
AO
DI
DO
P
=
=
=
=
=
15
8
5
10
28
7
11
1
13
14
2
P
AO
DI
AI
DO
P
P
P
AI
AI
DI
Analog Input
Analog Output
Digital Input
Digital Output
Power
PIN CONFIGURATION
V
LOGIC
1
2
3
4
5
6
7
8
9
10
28
27
STS
DB11(MSB)
STS
REGISTERS / 3-STATE OUTPUT BUFFERS
CONTROL
12/8
CS
A
0
R/C
CE
V
CC
REF OUT
26
DB10
25
24
23
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0(LSB)
DGND
AD1674
TOP VIEW
(Not to Scale)
22
21
20
19
18
17
16
15
AGND
20k
REF IN
5k
BIP OFF
20V
IN
COMP
10k
10k
IDAC
12
12
DB11 (MSB)
DB0 (LSB)
AGND
REF IN
V
EE 11
BIP OFF
10V
IN
20V
IN
12
13
14
5k
2.5k
2.5k
SHA
DAC
10V
IN
5k
AD1674
REV. C
–7–
AD [ ANALOG DEVICES ]
