Time − 0.1 ms/div

Capacitor Voltage

Output Voltage

Input Voltage

See Figure 9

C − Capacitance −

µF

10

1

100

10

1

0.1

0.01

0.001

(5 V to 15 V)

Output

GND

OUT

CONT

RESET

DISCH

THRES

TRIG

Input

5

8

4

7

6

2

3

1

Pin numbers shown are for the D, JG, P, PS, and PW packages.

NA555, NE555, SA555, SE555

SLFS022I – SEPTEMBER 1973 – REVISED SEPTEMBER 2014

www.ti.com

Feature Description (continued)

Figure 9. Circuit for Monostable Operation

Monostable operation is initiated when TRIG voltage falls below the trigger threshold. Once initiated, the

sequence ends only if TRIG is high for at least 10 µs before the end of the timing interval. When the trigger is

grounded, the comparator storage time can be as long as 10 µs, which limits the minimum monostable pulse

width to 10 µs. Because of the threshold level and saturation voltage of Q1, the output pulse duration is

independent of the supply voltage, so long as the supply voltage is constant during the time interval.

Applying a negative-going trigger pulse simultaneously to RESET and TRIG during the timing interval discharges

C and reinitiates the cycle, commencing on the positive edge of the reset pulse. The output is held low as long

Figure 10. Typical Monostable Waveforms

Figure 11. Output Pulse Duration vs Capacitance

10

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