SA555DT Datasheet, PDF (9/20 Pages) STMicroelectronics – General-purpose single bipolar timers

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, R_L = 1kΩ
Figure 14. Pulse duration versus R1C1
C
(μF)
10
1.0
0.1
0.01
R1=
1k^Ω
10k^Ω_100k
Ω
1M^Ω_10MΩ
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 V_CC and 2/3 V_CC.
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