lmc555 National Semiconductor Corporation, lmc555 Datasheet - Page 7

• Manufacturer Part Number: lmc555
• Description: Cmos Timer
• Manufacturer: National Semiconductor Corporation

Application Information
V
TIME = 0.2 ms/Div. Bottom Trace: Output Voltage 2 V/Div.
R
C = 0.01 µF
PULSE POSITION MODULATOR
This application uses the timer connected for astable opera-
tion, as in Figure 10, with a modulating signal again applied
to the control voltage terminal. The pulse position varies with
the modulating signal, since the threshold voltage and hence
the time delay is varied. Figure 11 shows the waveforms
generated for a triangle wave modulation signal.
CC
A
= 9.1 kΩ
= 5V
FIGURE 9. Pulse Width Modulator Waveforms
FIGURE 10. Pulse Position Modulator
Top Trace: Modulation 1 V/Div.
(Continued)
00866915
00866921
7
V
TIME = 0.1 ms/Div.
R
R
C = 0.01 µF
50% DUTY CYCLE OSCILLATOR
The frequency of oscillation is
Bumps are numbered counter-clockwise
CC
A
B
= 3.9 kΩ
= 3 kΩ
FIGURE 11. Pulse Position Modulator Waveforms
= 5V
f = 1/(1.4 R
FIGURE 12. 50% Duty Cycle Oscillator
micro SMD Marking Orientation
C
C)
Bottom Trace: Output Voltage 2 V/Div.
Top Trace: Modulation Input 1 V/Div.
Top View
00866923
00866916
www.national.com
00866906