LMC555CM National Semiconductor, LMC555CM Datasheet - Page 6

• Manufacturer Part Number: LMC555CM
• Description: IC, TIMER, SINGLE, 3MHZ, 15V, 8-SOIC
• Manufacturer: National Semiconductor

Specifications of LMC555CM

• Operating Mode: Astable
• No. Of Timers: 1
• Clock External Input: Yes
• Supply Voltage Range: 2V To 15V
• Digital Ic Case Style: SOIC
• No. Of Pins: 8
• Frequency: 3MHz
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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Figure 5
eration.
V
TIME = 20 µs/Div.
R
R
C = 0.01 µF
The charge time (output high) is given by
And the discharge time (output low) by:
Thus the total period is:
The frequency of oscillation is:
Figure 6
Values. The duty cycle, as a fraction of total period that the
output is low, is:
CC
A
B
= 3.9 kΩ
= 9 kΩ
= 5V
shows the waveform generated in this mode of op-
may be used for quick determination of these RC
FIGURE 6. Free Running Frequency
FIGURE 5. Astable Waveforms
T = t
Top Trace: Output 5 V/Div.
Bottom Trace: Capacitor Voltage 1 V/Div.
1
t
1
+ t
= 0.693 (R
t
2
2
= 0.693 (R
= 0.693 (R
A
+ R
B
A
)C
+ 2R
B
)C
B
)C
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6
FREQUENCY DIVIDER
The monostable circuit of
divider by adjusting the length of the timing cycle.
shows the waveforms generated in a divide by three circuit.
V
TIME = 20 µs/Div. Middle Trace: Output 2 V/Div.
R
C = 0.01 µF
PULSE WIDTH MODULATOR
When the timer is connected in the monostable mode and
triggered with a continuous pulse train, the output pulse width
can be modulated by a signal applied to the Control Voltage
Terminal.
waveform examples.
CC
A
= 9.1 kΩ
= 5V
FIGURE 7. Frequency Divider Waveforms
Figure 8
FIGURE 8. Pulse Width Modulator
Top Trace: Input 4 V/Div.
Bottom Trace: Capacitor 2 V/Div.
shows the circuit, and in
Figure 1
can be used as a frequency
Figure 9
866914
are some
Figure 7
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