AD678
PIN DESCRIPTION
28-Lead DIP 44-Lead
Symbol
Pin No.
JLCC Pin No. Type Name and Function
AGND
AIN
BIPOFF
7
6
10
11
10
15
P
AI
AI
Analog Ground. This is the ground return for AIN only.
Analog Signal Input.
Bipolar Offset. Connect to AGND for +10 V input unipolar mode and straight binary
output coding. Connect to REFOUT through 50 Ω resistor for 5 V input bipolar mode
and twos complement binary output coding. See Figures 7 and 8.
Chip Select. Active LOW.
CS
DGND
4
14
6
23
DI
P
Digital Ground
DB11–DB4
26–19
40, 39, 37, 36, DO
35, 34, 33, 31
Data Bits 11 through 4. In 12-bit format (see 12/8 pin), these pins provide the upper 8 bits
of data. In 8-bit format, these pins provide all 12 bits in two bytes (see R/L pin).
Active HIGH.
DB3, DB2
18, 17
16
30, 27
DO
Data Bits 3 and 2. In 12-bit format, these pins provide Data Bit 3 and Data Bit 2.
Active HIGH. In 8-bit format they are undefined and should be tied to VDD
In 12-bit format, Data Bit 1. Active HIGH.
.
DB1 (R/L)
DB0 (HBE) 15
EOC
26
25
42
DO
DO
DO
In 12-bit format, Data Bit 0. Active HIGH.
27
End-of-Convert. EOC goes LOW when a conversion starts and goes HIGH when the
conversion is finished. In asynchronous mode, EOC is an open drain output and
requires an external 3 kΩ pull-up resistor. See EOCEN and SYNC pins for information
on EOC gating.
EOCEN
HBE (DB0) 15
1
1
25
DI
DI
End-Of-Convert Enable. Enables EOC pin. Active LOW.
In 8-bit format, High Byte Enable. If LOW, output contains high byte. If HIGH, output
contains low byte.
OE
2
3
DI
Output Enable. The falling edge of OE enables DB11–DB0 in 12-bit format and
DB11–DB4 in 8-bit format. Gated with CS. Active LOW.
Reference Input. +5 V input gives 10 V full-scale range.
+5 V Reference Output. Tied to REFIN through 50 Ω resistor for normal operation.
In 8-bit format, Right/Left justified. Sets alignment of 12-bit result within 16-bit field.
Tied to VDD for right-justified output and tied to DGND for left-justified output.
Start Convert. Active LOW. See SYNC pin for gating.
SYNC Control. If tied to VDD (synchronous mode), SC, EOC and EOCEN are gated
by CS. If tied to DGND (asynchronous mode), SC and EOCEN are independent of CS,
and EOC is an open drain output. EOC requires an external 3 kΩ pull-up resistor in
asynchronous mode.
REFIN
REFOUT
R/L (DB1)
9
8
16
14
12
26
AI
AO
DI
SC
SYNC
3
13
5
21
DI
DI
VCC
VEE
VDD
12/8
11
5
28
12
17
8
43
19
P
P
P
DI
+12 V Analog Power.
–12 V Analog Power.
+5 V Digital Power.
Twelve/eight-bit format. If tied HIGH, sets output format to 12-bit parallel. If tied
LOW, sets output format to 8-bit multiplexed.
No Connect
2, 4, 7, 9, 13,
16, 18, 20, 22,
24, 28, 29, 32,
38, 41, 44
These pins are unused and should be connected to DGND or VDD.
Type: AI = Analog Input; AO = Analog Output; DI = Digital Input (TTL and 5 V CMOS compatible); DO = Digital Output (TTL and 5 V CMOS compatible).
All DO pins are three-state drivers; P = Power.
PIN CONFIGURATIONS
DIP PACKAGE
JLCC PACKAGE
1
2
3
4
5
6
7
8
9
28
27
26
25
24
23
22
21
20
19
18
EOCEN
OE
V
DD
EOC
DB11
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
6
5
4
3
2
44 43 42 41 40
SC
PIN 1
NC
7
8
39
DB10
NC
IDENTIFIER
CS
V
EE
38
37
36
V
EE
DB9
DB8
NC
9
AIN
10
11
AIN
AD678
TOP VIEW
AD678
TOP VIEW
(Not to Scale)
35
34
DB7
DB6
DB5
NC
AGND
AGND
REF
12
13
14
15
OUT
NC
REF
OUT
33
32
31
30
REF
IN
REF
IN
BIPOFF 10
11
DB4
BIPOFF
NC
16
17
DB3
NC
V
CC
V
CC
29
12/8 12
17 DB2
16
18 19 20 21 22 23 24 25 26 27 28
13
14
SYNC
DGND
DB1 (R/L)
15 DB0 (HBE)
NC = NO CONNECT
–6–
REV. C