Datasheet

AD652
Rev. C | Page 17 of 28
00798-023
+15V
1
2
3
4
5
6
7
200pF
–15V
8
16
15
14
13
12
11
10
9
ONE
SHOT
AND
"D"
FLOP
QCK
D
Q
1mA
20kΩ
AD652
SYNCHRONOUS
VOLTAGE-TO-
FREQUENCY
CONVERTER
5V
REFERENCE
+5V
0.02µF
–
+
V2
0V–10V
f
OUT
f
C
+15V
1
2
3
4
5
6
7
–15V
8
16
15
14
13
12
11
10
9
ONE
SHOT
AND
"D"
FLOP
QCK
D
Q
1mA
20kΩ
AD652
SYNCHRONOUS
VOLTAGE-TO-
FREQUENCY
CONVERTER
5V
REFERENCE
400pF
V
OUT
2kΩ
+5V
1MHz
CLOCK
INPUT
4
3
OSC/DRIVER
A
B
74LS86
C
65
8
1
2
7
C
T
200pF
C1
500pF
1kΩ
R
PU
2.87kΩ
R
T
1kΩ
R3
1kΩ
R2
2kΩ
R1
8.06kΩ
V1
0V–10V
+5V
AD654
Figure 23. Frequency Output Multiplier
FREQUENCY OUTPUT MULTIPLIER
The AD652 can serve as a frequency output multiplier when
used in conjunction with a standard voltage-to-frequency
converter. Figure 23 shows the low cost AD654 VFC being used
as the clock input to the AD652. Also shown is a second AD652
in the F/V mode. The AD654 is set up to produce an output
frequency of 0 kHz to 500 kHz for an input voltage (V
1
) range
of 0 V to 10 V. The use of R4, C1, and the XOR gate doubles this
output frequency from 0 kHz–500 kHz to 0 MHz–1 MHz.
This 1 MHz full-scale frequency is then used as the clock input
to the AD652 SVFC. Because the AD652 full-scale output
frequency is one-half the clock frequency, the 1 MHz FS clock
frequency establishes a 500 kHz maximum output frequency for
the AD652 when its input voltage (V
2
) is 10 V. The user there-
fore has an output frequency range from 0 kHz to 500 kHz,
which is proportional to the product of V
1
and V
2
.