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ICL8038 Datasheet, PDF (7/10 Pages) Intersil Corporation – Precision Waveform Generator/Voltage Controlled Oscillator | |||
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ICL8038
RA
RB
74
R
8
5
ICL8038
69
3
V+
RL
FM
10
11
12 2
C
81K
V- OR GND
FIGURE 5A. CONNECTIONS FOR FREQUENCY MODULATION
SWEEP
RA
VOLTAGE
4
RB
5
69
V+
RL
8
ICL8038
3
10
11
12 2
C
81K
V- OR GND
FIGURE 5B. CONNECTIONS FOR FREQUENCY SWEEP
FIGURE 5.
Typical Applications
The sine wave output has a relatively high output impedance
(1k⦠Typ). The circuit of Figure 6 provides buffering, gain
and amplitude adjustment. A simple op amp follower could
also be used.
RA
74
RB
5
8
ICL8038
6 2 AMPLITUDE
+
100K 741
-
V+
20K
10
11
4.7K
C
V-
FIGURE 6. SINE WAVE OUTPUT BUFFER AMPLIFIERS
With a dual supply voltage the external capacitor on Pin 10 can
be shorted to ground to halt the ICL8038 oscillation. Figure 7
shows a FET switch, diode ANDed with an input strobe signal
to allow the output to always start on the same slope.
RA
RB
V+
15K
74
5
9
8
ICL8038
1N914
11
10 2
C
2N4392
-15V
1N914
STROBE
100K
OFF
ON
+15V (+10V)
-15V (-10V)
FIGURE 7. STROBE TONE BURST GENERATOR
To obtain a 1000:1 Sweep Range on the ICL8038 the
voltage across external resistors RA and RB must decrease
to nearly zero. This requires that the highest voltage on
control Pin 8 exceed the voltage at the top of RA and RB by a
few hundred mV. The Circuit of Figure 8 achieves this by
using a diode to lower the effective supply voltage on the
ICL8038. The large resistor on pin 5 helps reduce duty cycle
variations with sweep.
The linearity of input sweep voltage versus output frequency
can be signiï¬cantly improved by using an op amp as shown
in Figure 10.
0.1µF
1N457
DUTY CYCLE
1K
4.7K
4.7K
+10V
15K
10K
FREQ.
5
4
69
8
ICL8038
3
10
11
12 2
20K â15M
0.0047µF
DISTORTION
100K
-10V
FIGURE 8. VARIABLE AUDIO OSCILLATOR, 20Hz TO 20kHzY
7
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