HA17339A Series
2. Pulse Generator
The charge and discharge circuits in the circuit from figure 1 are separated by diodes in this circuit. (See figure 3.)
This allows the pulse width and the duty cycle to be set independently. Figure 4 shows the waveforms generated by
this circuit.
V
CC
R
1
1M
D
1
IS2076
R
2
100k D
2
IS2076
C
80pF
V
CC
1M
1M
1M
−
+
V
CC
Vout
HA17339A
Figure 3 Pulse Generator
Horizontal: 2 V/div, Vertical: 20
µs/div,
V
CC
= 5 V
Horizontal: 5 V/div, Vertical: 20
µs/div,
V
CC
= 15 V
Figure 4 Operating Waveforms
3. Voltage Controlled Oscillator
In the circuit in figure 5, comparator A
1
operates as an integrator, A
2
operates as a comparator with hysteresis, and
A
3
operates as the switch that controls the oscillator frequency. If the output Vout1 is at the low level, the A
3
output
will go to the low level and the A1 inverting input will become a lower level than the A1 noninverting input. The A1
output will integrate this state and its output will increase towards the high level. When the output of the integrator
A
1
exceeds the level on the comparator A
2
inverting input, A
2
inverts to the high level and both the output Vout1
and the A
3
output go to the high level. This causes the integrator to integrate a negative state, resulting in its output
decreasing towards the low level. Then, when the A
1
output level becomes lower than the level on the A
2
noninverting input, the output Vout1 is once again inverted to the low level. This operation generates a square wave
on Vout1 and a triangular wave on Vout2.
V
CC
100k
+V
C
0.1µ
Frequency
control
voltage
input
20k
50k
A
3
V
CC
= 30V
+250mV
<
+V
C
<
+50V
700Hz
<
/
<
100kHz
20k
V
CC
−
V
CC
/2
Output 2
10
−
V
CC
500p
A
1
3k
0.01µ
V
CC
/2
5.1k
+
−
100k
V
CC
3k
A
2
Output 1
V
CC
HA17339A
+
HA17339A
HA17339A
+
Figure 5 Voltage Controlled Oscillator
Rev.3.00 Mar 10, 2006 page 10 of 14
RENESAS [ RENESAS TECHNOLOGY CORP ]
