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Número de pieza

componentes Descripción

Fabricante

NE555

General-purpose single bipolar timers

STMicroelectronics 

NE555 - SA555 - SE555

Figure 13. Waveforms in monostable operation

t = 0.1 ms / div

INPUT = 2.0V/div

OUTPUT VOLTAGE = 5.0V/div

Application information

CAPACITOR VOLTAGE = 2.0V/div

R1 = 9.1kΩ, C1 = 0.01μF, RL = 1kΩ

Figure 14. Pulse duration versus R1C1

C

(μF)

10

1.0

0.1

0.01

R1=

1kΩ

10kΩ100k

Ω

1MΩ10MΩ

0.001

10

μs

100

μs

1.0

ms

10 100

ms ms

10

s

(t d )

4.2

Astable operation

When the circuit is connected as shown in Figure 15 (pins 2 and 6 connected) it triggers

itself and free runs as a multi-vibrator. The external capacitor charges through R1 and R2

and discharges through R2 only. Thus the duty cycle can be set accurately by adjusting the

ratio of these two resistors.

In the astable mode of operation, C1 charges and discharges between 1/3 VCC and 2/3 VCC.

As in the triggered mode, the charge and discharge times and, therefore, frequency are

independent of the supply voltage.

Doc ID 2182 Rev 6

9/20

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