Datasheet
AD678
REV. C
–6–
PIN DESCRIPTION
28-Lead DIP 44-Lead
Symbol Pin No. JLCC Pin No. Type Name and Function
AGND 7 11 P Analog Ground. This is the ground return for AIN only.
AIN 6 10 AI Analog Signal Input.
BIPOFF 10 15 AI Bipolar Offset. Connect to AGND for +10 V input unipolar mode and straight binary
output coding. Connect to REF
OUT
through 50 Ω resistor for ± 5 V input bipolar mode
and twos complement binary output coding. See Figures 7 and 8.
CS 4 6 DI Chip Select. Active LOW.
DGND 14 23 P Digital Ground
DB11–DB4 26–19 40, 39, 37, 36, DO Data Bits 11 through 4. In 12-bit format (see 12/8 pin), these pins provide the upper 8 bits
35, 34, 33, 31 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 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 V
DD
.
DB1 (R/L) 16 26 DO In 12-bit format, Data Bit 1. Active HIGH.
DB0 (HBE) 15 25 DO In 12-bit format, Data Bit 0. Active HIGH.
EOC 27 42 DO 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 1 1 DI End-Of-Convert Enable. Enables EOC pin. Active LOW.
HBE (DB0) 15 25 DI 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.
REF
IN
9 14 AI Reference Input. +5 V input gives 10 V full-scale range.
REF
OUT
8 12 AO +5 V Reference Output. Tied to REF
IN
through 50 Ω resistor for normal operation.
R/L (DB1) 16 26 DI In 8-bit format, Right/Left justified. Sets alignment of 12-bit result within 16-bit field.
Tied to V
DD
for right-justified output and tied to DGND for left-justified output.
SC 3 5 DI Start Convert. Active LOW. See SYNC pin for gating.
SYNC 13 21 DI SYNC Control. If tied to V
DD
(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.
V
CC
11 17 P +12 V Analog Power.
V
EE
5 8 P –12 V Analog Power.
V
DD
28 43 P +5 V Digital Power.
12/8 12 19 DI 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, These pins are unused and should be connected to DGND or V
DD
.
16, 18, 20, 22,
24, 28, 29, 32,
38, 41, 44
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
EOCEN
OE
V
EE
AIN
AGND
SC
CS
REF
OUT
REF
IN
BIPOFF
V
CC
12/8
SYNC
DGND
13
18
1
2
28
27
5
6
7
24
23
22
3
4
26
25
8
21
920
10 19
11
12 17
16
14
15
TOP VIEW
(Not to Scale)
AD678
V
DD
EOC
DB9
DB8
DB7
DB11
DB10
DB6
DB5
DB4
DB3
DB2
DB1 (R/L)
DB0 (HBE)
6 5 4 3 2 44 43 42 41 40
18 19 20 21 22 24 25 26 27 2823
7
8
9
10
11
12
13
14
15
16
17
39
38
37
36
35
34
33
32
31
30
29
PIN 1
IDENTIFIER
TOP VIEW
NC
NC
NC
NC
V
EE
AIN
AGND
REF
OUT
REF
IN
BIPOFF
V
CC
NC
NC
NC
DB9
DB8
DB7
DB10
DB6
DB5
DB4
DB3
CS
SC
NC
OE
NC
EOCEN
V
DD
EOC
DB11
NC
NC
NC
NC
DGND
NC
NC
12/8
SYNC
DB0 (HBE)
DB1 (R/L)
DB2
NC
AD678
NC = NO CONNECT