Datasheet

AD781
REV. A
–8–
C1509–10–2/91
PRINTED IN U.S.A.
AD781 TO AD674 INTERFACE
Figure 9 shows a typical data acquisition circuit using the
AD781, a high linearity, low aperture jitter SHA and the AD674
a 12-bit high speed ADC. The time between the AD674 status
line going high and the actual start of conversion allows the
AD781 to settle to 0.01%. As a result, the AD674 status line
can be used to control the AD781; only an inverter is needed to
interface the two devices.
CS
A
0
10 V
IN
DGND
20 V
IN
REF IN
REF OUT
BIP OFFSET
R/C
AGND
NC
GAIN
CONVERT
0.1µF
+12V
V
CC
IN
GND
0.1µF
–12V
V
IN
OUT
AD781
100Ω
100Ω
OFFSET
28
15
3
4
13
14
10
8
12
5
9
5
8
2
3
4
NC
6
NC
1
7
AD674
–12V
4.7µF
0.1µF
11
+12V
4.7µF
0.1µF
7
D0–11
12-BIT
THREE-STATE
DATA
16
27
STS
STATUS
S/H
7404
OR EQUIV.
CE
+5V
6
V
L
1
2
12/8
0.1µF
V
EE
Figure 9. AD781 to AD674 Interface
20
–140
–100
–120
0
–60
–80
–40
–20
0
3 7 10 13 16 20
23
26
30 33
FREQUENCY BINS – kHz
AMPLITUDE – dB
Figure 10. FFT Plot of AD781 to AD674 Interface,
F
IN
= 1 kHz
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
Cerdip (Q) Package Mini-DIP (N) Package