NE555N Просмотр технического описания (PDF) - Harris Semiconductor
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производитель
NE555N
Timers for Timing Delays and Oscillator Application in Commercial, Industrial and Military Equipment
Harris Semiconductor
NE555N Datasheet PDF : 6 Pages
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CA555, CA555C, LM555, LM555C, NE555
RESET
R1
4
V+
5V
680
7
8
EO
CA555
3
6
5
1N4001
1
2
10K
RELAY
CT
4.7K
680 COIL
0.01µF
S1
START
NOTE: All resistance values are in ohms.
FIGURE 1. RESET TIMER (MONOSTABLE OPERATION)
Since the charge rate and threshold level of the comparator
are both directly proportional to V+, the timing interval is rel-
atively independent of supply voltage variations. Typically,
the timing varies only 0.05% for a 1V change in V+.
Applying a negative pulse simultaneously to the reset termi-
nal (4) and the trigger terminal (2) during the timing cycle
discharges CT and causes the timing cycle to restart.
Momentarily closing only the reset switch during the timing
interval discharges CT, but the timing cycle does not restart.
Figure 2 shows the typical waveforms generated during this
mode of operation, and Figure 3 gives the family of time
delay curves with variations in R1 and CT.
3V SWITCH S1 “OPEN”
INPUT
VOLTAGE (TERMINAL 2)
0SWITCH S1 “CLOSED”
100
TA = 25oC
V+ = 5V
10
1
R1 = 1kΩ
10kΩ
100kΩ
0.1
1MΩ
10MΩ
0.01
0.001
10-5
10-4
10-3
10-2
10-1
1
10
TIME DELAY(s)
FIGURE 3. TIME DELAY vs RESISTANCE AND CAPACITANCE
Repeat Cycle Timer (Astable Operation)
Figure 4 shows the CA555 connected as a repeat cycle
timer. In this mode of operation, the total period is a function
of both R1 and R2.
R1
4
7
8
EO
R2
CA555
3
6
5
1
2
RELAY
COIL
V+
5V
CT
0.01µF
3.3V
CAPACITOR
VOLTAGE (TERMINALS 6, 7)
0
tD
5V
OUTPUT
VOLTAGE
(TERMINAL 3)
0
FIGURE 2. TYPICAL WAVEFORMS FOR RESET TIMER
FIGURE 4. REPEAT CYCLE TIMER (ASTABLE OPERATION)
T = 0.693 (R1 + 2R2) CT = t1 + t2
where t1 = 0.693 (R1 + R2) CT
and t2 = 0.693 (R2) CT
the duty cycle is:
t--1----t-+-1----t-2-- = R--R---1--1--+--+---2--R--R--2--2--
Typical waveforms generated during this mode of operation
are shown in Figure 5. Figure 6 gives the family of curves of
free running frequency with variations in the value of
(R1 + 2R2) and CT.
8-6
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