AD652_15 Datasheet, PDF (17/28 Pages) Analog Devices – Monolithic Synchronous Voltage-to-Frequency Converter

+5V
R1 R2
8.06kΩ 2kΩ
V1
0V–10V
4
R3
1kΩ
3
AD654
5
R_T
1kΩ
8
OSC/DRIVER
6
7
C_T
200pF
R_PU
2.87kΩ
1
A
1kΩ
B
C
2
C1
500pF
74LS86
f_C
+15V
0.02µF
V2–
0V–10V+
AD652
SYNCHRONOUS
VOLTAGE-TO-
1
FREQUENCY
CONVERTER
2
3
4
5
6
20kΩ
7
1mA
8
5V
REFERENCE
16
15
14
13
ONE
12
SHOT
11
10
Q CK
9
AND D _"D"
Q FLOP
+5V
f_OUT
AD652
V_OUT
–15V
+15V
400pF
200pF
AD652
SYNCHRONOUS
VOLTAGE-TO-
1
FREQUENCY
CONVERTER
2
3
4
5
6
20kΩ
7
1mA
8
+5V
5V
REFERENCE
16
15
14
13
ONE
12
SHOT
11
10
Q CK
9
AND D _"D"
Q FLOP
2kΩ
1MHz
CLOCK
INPUT
–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 17 of 28