HA17901 データシートの表示（PDF） - Renesas Electronics

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HA17901

Quadruple Comparators

Renesas Electronics 

HA17901 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.

VCC

R1 1M D1 IS2076

R2 100k D2 IS2076

C

−

VCC

80pF

HA17901

VCC

+

1M

Vout

1M

1M

Figure 3 Pulse Generator

Horizontal: 2 V/div, Vertical: 20 µs/div, VCC = 5 V Horizontal: 5 V/div, Vertical: 20 µs/div, VCC = 15 V

Figure 4 Operating Waveforms

3. Voltage Controlled Oscillator

In the circuit in figure 5, comparator A1 operates as an integrator, A2 operates as a comparator with hysteresis, and

A3 operates as the switch that controls the oscillator frequency. If the output Vout1 is at the low level, the A3 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

A1 exceeds the level on the comparator A2 inverting input, A2 inverts to the high level and both the output Vout1

and the A3 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 A1 output level becomes lower than the level on the A2

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.

VCC

VCC

500p

100k

−

A1

3k

5.1k

+VC

10 HA17901

0.1µ

+

0.01µ

Frequency

control

20k

20k

VCC/2

voltage

input

50k

VCC

A3

−

VCC/2

VCC = 30V

+250mV < +VC < +50V

700Hz < / < 100kHz

HA17901

+

100k

VCC

+

A2

HA17901

−

VCC

3k

Output 1

Output 2

Figure 5 Voltage Controlled Oscillator

Rev.1.00 Jun 15, 2005 page 9 of 12

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