LM555CM National Semiconductor, LM555CM Datasheet - Page 10

• Manufacturer Part Number: LM555CM
• Description: IC, TIMER, SINGLE, 16V, 8-SOIC
• Manufacturer: National Semiconductor

Specifications of LM555CM

• Operating Mode: Astable / Monostable
• No. Of Timers: 1
• Clock External Input: Yes
• Supply Voltage Range: 4.5V To 16V
• Digital Ic Case Style: SOIC
• No. Of Pins: 8
• Operating Temperature Range: 0°C To +70°C
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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Applications Information
V
TIME = 20µs/DIV. Middle Trace: Output 5V/Div.
R
R
R
C = 0.01 µF
50% DUTY CYCLE OSCILLATOR
For a 50% duty cycle, the resistors R
connected as in Figure 14. The time period for the output
high is the same as previous, t
low it is t
Thus the frequency of oscillation is
CC
1
2
E
= 47kΩ
= 100kΩ
= 2.7 kΩ
= 5V
2
=
Bottom Trace: Capacitor Voltage 1V/Div.
Top Trace: Input 3V/Div.
FIGURE 13. Linear Ramp
1
= 0.693 R
A
A
and R
C. For the output
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(Continued)
B
may be
10
Note that this circuit will not oscillate if R
R
down to 1/3 V
ADDITIONAL INFORMATION
Adequate power supply bypassing is necessary to protect
associated circuitry. Minimum recommended is 0.1µF in par-
allel with 1µF electrolytic.
Lower comparator storage time can be as long as 10µs
when pin 2 is driven fully to ground for triggering. This limits
the monostable pulse width to 10µs minimum.
Delay time reset to output is 0.47µs typical. Minimum reset
pulse width must be 0.3µs, typical.
Pin 7 current switches within 30ns of the output (pin 3)
voltage.
A
because the junction of R
FIGURE 14. 50% Duty Cycle Oscillator
CC
and trigger the lower comparator.
A
and R
B
B
cannot bring pin 2
is greater than 1/2
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