Datasheet

REV. C–6–
AD674B/AD774B
PIN FUNCTION DESCRIPTIONS
Symbol Pin No. Type* Name and Function
AGND 9 P Analog Ground (Common)
A
0
4 DI 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,
and A
0
= 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 DI Chip Enable. Chip Enable is Active HIGH and is used to initiate a convert or read operation.
CS 3 DI Chip Select. Chip Select is Active LOW.
DB11–DB8 27–24 DO Data Bits 11 through 8. In the 12-bit format (see 12/8 and A
0
pins) these pins provide the upper
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.
DB7–DB4 23–20 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 A
0
is LOW and all zeroes when A
0
is HIGH.
DB3–DB0 19–16 DO Data Bits 3 through 0. In both the 12-bit and 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.
DGND 15 P Digital Ground (Common)
REF OUT 8 AO 10 V Reference Output
R/C 5 DI 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 standalone mode, the falling edge of R/C initiates a conversion.
REF IN 10 AI Reference Input is connected through a 50 Ω resistor to +10 V Reference for normal operation.
STS 28 DO Status is Active HIGH when a conversion is in progress and goes LOW when the conversion is
completed.
V
CC
7 P +12 V/+15 V Analog Supply
V
EE
11 P –12 V/–15 V Analog Supply
V
LOGIC
1 P 5 V Logic Supply
10 V
IN
13 AI 10 V Span Input, 0 V to +10 V unipolar mode or –5 V to +5 V bipolar mode. When using the
20 V Span, 10 V
IN
should not be connected.
20 V
IN
14 AI 20 V Span Input, 0 V to +20 V unipolar mode or –10 V to +10 V bipolar mode. When using the
10 V Span, 20 V
IN
should not be connected.
12/8 2 DI 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).
*Types: AI = Analog Input, AO = Analog Output, DI = Digital Input, DO = Digital Output, P = Power
PIN CONFIGURATION
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
AD674B
OR
AD774B
V
LOGIC
12/8
CS
A
0
R/C
CE
V
CC
REF OUT
AGND
REF IN
V
EE
BIP OFF
10 V
IN
20 V
IN
STS
DB11 (MSB)
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
DB0 (LSB)
DGND