AD652
+5V
R
PU
2.87kΩ
8
1
2
AD654
R1
R2
A
B
8.06kΩ 2kΩ
OSC/DRIVER
C
4
3
1kΩ
R3
1kΩ
V1
74LS86
0V–10V
C1
500pF
5
6
7
fC
R
T
1kΩ
C
T
200pF
+15V
AD652
SYNCHRONOUS
VOLTAGE-TO-
FREQUENCY
CONVERTER
5V
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
REFERENCE
0.02µF
ONE
SHOT
+5V
–
V2
20kΩ
0V–10V
+
1mA
Q
CK
"D"
D
fOUT
AND
Q FLOP
200pF
–15V
+15V
+5V
AD652
SYNCHRONOUS
VOLTAGE-TO-
FREQUENCY
CONVERTER
5V
2kΩ
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
REFERENCE
V
OUT
400pF
ONE
SHOT
1MHz
CLOCK
INPUT
20kΩ
1mA
Q
CK
"D"
D
AND
Q FLOP
–15V
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 (V1) 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 (V2) 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 V1 and V2.
Rev. C | Page ±7 of 28
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