STMICROELECTRONICS SA555

NE555
SA555 - SE555
GENERAL PURPOSE SINGLE BIPOLAR TIMERS
LOW TURN OFF TIME
MAXIMUM
OPERATING
FREQUENCY
GREATER THAN 500kHz
TIMING FROM MICROSECONDS TO HOURS
OPERATES IN BOTH ASTABLE AND
MONOSTABLE MODES
HIGH OUTPUT CURRENT CAN SOURCE OR
SINK 200mA
ADJUSTABLE DUTY CYCLE
TTL COMPATIBLE
TEMPERATURE STABILITY OF 0.005%
PERoC
DESCRIPTION
The NE555 monolithic timing circuit is a highly stable
controller capableof producing accuratetime delays
or oscillation. In the time delay mode of operation,
the time is precisely controlled by one external resistor and capacitor.For a stableoperation as an oscillator, the free running frequency and the duty cycle are both accurately controlled with two external
resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output structure can source or sink up to 200mA. The
NE555 is available in plastic and ceramic minidip
package and in a 8-lead micropackage and in metal
can package version.
N
DIP8
(Plastic Package)
D
SO8
(Plastic Micropackage)
ORDER CODES
Part
Number
Package
Temperature
Range
N
D
NE555
0oC, 70oC
•
•
SA555
–40oC, 105oC
•
•
•
•
o
o
–55 C, 125 C
SE555
PIN CONNECTIONS (top view)
April 1995
1
8
2
7
3
6
4
5
1
2
3
4
5
6
7
8
- GND
- Trigger
- Output
- Reset
- Control voltage
- Threshold
- Discharge
- VCC
1/10
555-01.TBL
..
..
.
..
.
NE555/SA555/SE555
BLOCK DIAGRAM
VCC+
5kΩ
COMP
THRESHOLD
CONTROL VOLTAGE
DISCHARGE
R
FLIP-FLOP
Q
5kΩ
COMP
OUT
TRIGGER
S
INHIBIT/
RESET
5kΩ
S
555-03.EPS
RESET
S - 808 6
SCHEMATIC DIAGRAM
CONTROL
VOLTAGE
OUTPUT
THRESHOLD
COMPARATOR
5
VCC
R2
830Ω
R1
4.7kΩ
R4 R8
1kΩ 5kΩ
R3
4.7kΩ
R12
6.8kΩ
Q21
Q5
Q6
Q7
Q8
Q19
Q9
Q22
Q20
R13
3.9kΩ
R11
5kΩ
THRESHOLD
Q1
Q2
Q23
Q3
R9
5kΩ
Q11 Q12
TRIGGER
2
D2
RESET
4
R14
220Ω
Q24
Q13
Q10
Q16
DISCHARGE
3
D1
R17
4.7kΩ
Q4
Q18
R16
100Ω
R15
4.7kΩ
Q15
7
Q17
Q14
R5
10kΩ
R6
100kΩ
R7
100kΩ
R10
5kΩ
1
TRIGGER COMPARATOR
555-04.EPS
GN D
FLIP FLOP
ABSOLUTE MAXIMUM RATINGS
Vcc
Toper
Tj
Tstg
2/10
Parameter
Value
Supply Voltage
Operating Free Air Temperature Range
Junction Temperature
Storage Temperature Range
18
for NE555
for SA555
for SE555
Unit
V
0 to 70
–40 to 105
–55 to 125
o
150
o
–65 to 150
o
C
C
C
555-02.TBL
Symbol
NE555/SA555/SE555
Symbol
VCC
Vth, Vtrig, Vcl, Vreset
Parameter
Supply Voltage
Maximum Input Voltage
SE555
NE555 - SA555
Unit
4.5 to 18
4.5 to 16
V
VCC
VCC
V
555-03.TBL
OPERATING CONDITIONS
ELECTRICAL CHARACTERISTICS
T amb = +25oC, VCC = +5V to +15V (unless otherwise specified)
ICC
VCL
Vth
Ith
Vtrig
Itrig
Parameter
SE555
Min.
Max.
3
10
2
Timing Error (monostable)
(RA = 2k to 100kΩ, C = 0.1µF)
Initial Accuracy - (note 2)
Drift with Temperature
Drift with Supply Voltage
0.5
30
0.05
Timing Error (astable)
(RA, RB = 1kΩ to 100kΩ, C = 0.1µF,
VCC = +15V)
Initial Accuracy - (note 2)
Drift with Temperature
Drift with Supply Voltage
1.5
90
0.15
Supply Current (RL ∞) (- note 1)
Low State
VCC = +5V
VCC = +15V
High State
VCC = 5V
Max.
5
12
3
10
2
6
15
2
100
0.2
1
50
0.1
3
0.5
2.25
150
0.3
9
2.6
10
3.33
11
4
Threshold Voltage
VCC = +15V
VCC = +5V
9.4
2.7
10
3.33
10.6
4
8.8
2.4
10
3.33
11.2
4.2
0.1
0.25
0.1
0.25
5
1.67
5.2
1.9
5
1.67
5.6
2.2
0.5
0.9
0.5
2.0
0.7
1
0.7
1
V
V
Threshold Current - (note 3)
µA
V
4.8
1.45
Trigger Current (Vtrig = 0V)
Reset Current
%
ppm/°C
%/V
%
ppm/°C
%/V
10.4
3.8
Trigger Voltage
VCC = +15V
VCC = +5V
Unit
mA
10
3.33
Reset Voltage - (note 4)
0.4
4.5
1.1
0.4
µA
V
mA
0.1
0.4
0.4
1
0.1
0.4
0.4
1.5
Low Level Output Voltage
VCC = +15V, IO(sink) = 10mA
IO(sink) = 50mA
IO(sink) = 100mA
IO(sink) = 200mA
VCC = +5V, IO(sink) = 8mA
IO(sink) = 5mA
0.1
0.4
2
2.5
0.1
0.05
0.15
0.5
2.2
0.1
0.4
2
2.5
0.3
0.25
0.25
0.75
2.5
High Level Output Voltage
VCC = +15V, IO(source) = 200mA
IO(source) = 100mA
VCC = +5V, IO(source) = 100mA
12.5
13.3
3.3
Vreset = +0.4V
Vreset = 0V
Notes :
Typ.
9.6
2.9
Ireset
VOH
Min.
Control Voltage level
VCC = +15V
VCC = +5V
Vreset
VOL
NE555 - SA555
Typ.
V
0.25
0.2
0.4
0.35
V
13
3
12.75
2.75
12.5
13.3
3.3
555-04.TBL
Symbol
1. Supply current when output is high is typically 1mA less.
2. Tested at VCC = +5V and VCC = +15V.
3. This will determine the maximum value of RA + RB for +15V operation the max total is R = 20MΩ and for 5V operation,
the max total R = 3.5MΩ.
3/10
NE555/SA555/SE555
ELECTRICAL CHARACTERISTICS (continued)
Parameter
SE555
Min.
NE555 - SA555
Typ.
Max.
20
100
Min.
Typ.
Max.
20
100
Idis (off)
Discharge Pin Leakage Current
(output high) (Vdis = 10V)
Vdis(sat)
Discharge pin Saturation Voltage
(output low) - (note 5)
VCC = +15V, Idis = 15mA
VCC = +5V, Idis = 4.5mA
180
80
480
200
180
80
480
200
Output Rise Time
Output Fall Time
100
100
200
200
100
100
300
300
Turn off Time - (note 6) (Vreset = VCC)
0.5
mV
0.5
ns
µs
5. No protection against excessive Pin 7 current is necessary, providing the package dissipation rating will not be exceeded.
6. Time mesaured from a positive going input pulse from 0 to 0.8x VCC into the threshold to the drop from high to low of the
output trigger is tied to treshold.
Figure 2 : Supply Current versus Supply Voltage
555-05.EPS
Figure 1 : Minimum Pulse Width Required for
Trigering
555-06.EPS
toff
Notes :
nA
Figure 4 : Low Output Voltage versus Output
Sink Current
555-07.EPS
Figure 3 : Delay Time versus Temperature
4/10
555-08.EPS
tr
tf
Unit
555-05.TBL
Symbol
NE555/SA555/SE555
Figure 6 : Low Output Voltage versus Output
Sink Current
Figure 8 : Delay Time versus Supply Voltage
555-12.EPS
555-11.EPS
Figure 7 : High Output Voltage Drop versus
Output
555-10.EPS
555-09.EPS
Figure 5 : Low Output Voltage versus Output
Sink Current
555-13.EPS
Figure 9 : Propagation Delay versus Voltage
Level of Trigger Value
5/10
NE555/SA555/SE555
APPLICATION INFORMATION
Figure 11
t = 0.1 ms / div
MONOSTABLE OPERATION
In the monostable mode, the timer functions as a
one-shot. Referring to figure 10 the external capacitor is initially held discharged by a transistor inside
the timer.
INPUT = 2.0V/div
Figure 10
OUTPUT VOLTAGE = 5.0V/div
VCC = 5 to 15V
Reset
R1
4
7
Output
6
5
3
1
C1
R1 = 9.1kΩ, C1 = 0.01µF, RL = 1kΩ
Control Voltage
0.01 µF
The circuit triggers on a negative-going input signal
when the level reaches 1/3 Vcc. Once triggered, the
circuit remains in this state until the set time has
elapsed, even if it is triggered again during this interval.The duration of the output HIGH stateis given
by t = 1.1 R1C1 and is easily determined by
figure 12.
Notice that since the charge rate and the threshold
level of the comparator are both directly proportional
to supply voltage, the timing interval is independent
of supply. Applying a negativepulse simultaneously
to the reset terminal (pin 4) and the trigger terminal
(pin 2) during the timing cycle discharges the external capacitor and causes the cycle to start over. The
timing cycle now starts on the positive edge of the
reset pulse. During the time the reset pulse in applied, the output is driven to its LOW state.
When a negativetrigger pulse is applied to pin 2, the
flip-flop is set, releasing the short circuit across the
external capacitor and driving the output HIGH. The
voltage across the capacitor increases exponentially with the time constantτ = R1C1. When the voltage across the capacitor equals 2/3 Vcc, the comparatorresets the flip-flop which then discharge the capacitor rapidly and drivers the output to its LOW
state.
Figure 11 shows the actual waveforms generatedin
this mode of operation.
When Reset is not used, it should be tied high to
avoid any possibly or false triggering.
6/10
CAPACITOR VOLTAGE = 2.0V/div
555-15.EPS
NE555
Figure 12
C
(µF)
10
=
R1
1.0
0.1
0.01
0.001
10
µs
100
µs
Ω
1k
kΩ
Ω
10
0k
10 MΩ
1
Ω
M
10
1.0
ms
10
ms
100
ms
10
s
(t d )
555-16.EPS
2
555-14.EPS
Trigger
8
ASTABLE OPERATION
When the circuit is connected as shown in figure 13
(pin 2 and 6 connected)it triggers itself and free runs
as a multivibrator. The external capacitor charges
through R1 and R2 and discharges through R2 only.
Thus the duty cycle may be precisely set by the ratio
of these two resistors.
In the astable mode of operation, C1 charges and
discharges between 1/3 Vcc and 2/3 Vcc. As in the
triggeredmode, the chargeand discharge times and
therefore frequency are independent of the supply
voltage.
NE555/SA555/SE555
Figure 13
Figure 15 : Free Running Frequency versus R1,
R2 and C1
VCC = 5 to 15V
R1
4
Output
7
3
NE555
Control
Voltage
1.0
R2
1
2
R1
+
0.1
6
5
R2
1k
Ω
10
k
Ω
10
0
1M kΩ
=
C1
555-17.EPS
0.01 µF
C
(µF)
10
8
1
10
100
1k
10k
f o (Hz)
555-18.EPS
Figure 14 shows actual waveforms generatedin this
mode of operation.
The charge time (output HIGH) is given by :
t1 = 0.693 (R1 + R2) C1
and the discharge time (output LOW) by :
t2 = 0.693 (R2) C1
Thus the total period T is given by :
T = t1 + t2 = 0.693 (R1 + 2R2) C1
The frequency ofoscillation is them :
1.44
1
f= =
T (R1 + 2R2) C1
and may be easily found by figure 15.
The duty cycle is given by :
R2
D=
R1 + 2R2
Ω
0.01
0.001
0.1
Ω
10
M
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 pin 5. Figure 16 shows the circuit.
Figure 16 : Pulse Width Modulator.
VCC
RA
8
4
Figure 14
Trigger
7
2
t = 0.5 ms / div
NE555
6
Modulation
Input
OUTPUT VOLTAGE = 5.0V/div
Output
3
5
C
555-20.EPS
1
R1 = R2 = 4.8kΩ, C1= 0.1µF, RL = 1kΩ
555-19.EPS
CAPACITOR VOLTAGE = 1.0V/div
7/10
NE555/SA555/SE555
LINEAR RAMP
When the pullup resistor, RA, in the monostable circuit is replaced by a constant current source, a linear
ramp is generated. Figure 17 shows a circuit configuration that will perform this function.
50% DUTY CYCLE OSCILLATOR
For a 50% duty cycle the resistors RA and RE may
beconnected as in figure19. The time preriod for the
output high is the same as previous,
t1 = 0.693 RA C.
For the output low it is t2 =
 RB ± 2RA 
[(RARB) ⁄ (RA + RB)] CLn 

 2RB ± RA 
Figure 17.
Thus the frequency of oscillation is f =
RE
R1
8
4
Trigger
1
t1 + t2
Note that this circuit will not oscillate if RB is greater
VCC
Figure 19 : 50% Duty Cycle Oscillator.
7
2
NE555
2N4250
or equiv.
VCC
6
VCC
C
Output
3
5
0.01µF
R2
RA
51kΩ
1
4
RB
555-21.EPS
Figure 18 shows waveforms generator by the linear
ramp.
The time interval is given by :
(2/3 VCC RE (R1+ R2) C
T=
VBE = 0.6V
R1 VCC ± VBE (R1+ R2)
8
7
2
22kΩ
NE55
Out
6
5
3
C
0.01µF
555-22.EPS
1
0.01µF
Figure 18 : Linear Ramp.
than 1/2 RA because the junction of RA and RB cannot bring pin 2 down to 1/3 VCC and trigger the lower
comparator.
555-23.EPS
ADDITIONAL INFORMATION
Adequate power supply bypassing is necessary to
protect associated circuitry. Minimum recommended is 0.1µF in parallel with 1µF electrolytic.
VCC = 5V
Time = 20µs/DIV
R 1 = 47kΩ
R 2 = 100kΩ
R E = 2.7kΩ
C = 0.01µF
8/10
Top trace : input 3V/DIV
Middle trace : output 5V/DIV
Bottom trace : output 5V/DIV
Bottom trace : capacitor voltage
1V/DIV
NE555/SA555/SE555
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC DIP OR CERDIP
B
I
L
a1
A
e4
b1
B1
b
E
e
e3
Z
Z
D
5
1
4
A
a1
B
b
b1
D
E
e
e3
e4
F
i
L
Z
Min.
Millimeters
Typ.
3.32
0.51
1.15
0.356
0.204
Max.
1.65
0.55
0.304
10.92
9.75
7.95
Min.
0.020
0.045
0.014
0.008
Max.
0.065
0.022
0.012
0.430
0.384
0.313
2.54
7.62
7.62
3.18
Inches
Typ.
0.131
0.100
0.300
0.300
6.6
5.08
3.81
1.52
0.125
0260
0.200
0.150
0.060
DIP8.TBL
Dimensions
PM-DIP8.EPS
F
8
9/10
NE555/SA555/SE555
PACKAGE MECHANICAL DATA
8 PINS - PLASTIC MICROPACKAGE (SO)
s
e3
b1
e
a1
b
A
a2
C
c1
a3
L
E
D
M
5
1
4
A
a1
a2
a3
b
b1
C
c1
D
E
e
e3
F
L
M
S
Min.
Millimeters
Typ.
0.1
0.65
0.35
0.19
0.25
Max.
1.75
0.25
1.65
0.85
0.48
0.25
0.5
Min.
Inches
Typ.
0.026
0.014
0.007
0.010
Max.
0.069
0.010
0.065
0.033
0.019
0.010
0.020
0.189
0.228
0.197
0.244
0.004
o
45 (typ.)
4.8
5.8
5.0
6.2
1.27
3.81
3.8
0.4
0.050
0.150
4.0
1.27
0.6
0.150
0.016
0.157
0.050
0.024
o
8 (max.)
SO8.TBL
Dimensions
PM-SO8.EPS
F
8
 1994 SGS-THOMSON Microelectronics - All Rights Reserved
SGS-THOMSON Microelectronics GROUP OF COMPANIES
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10/10
ORDER CODE :
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which
may result from its use. No licence is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON
Microelectronics. Specifications mentioned in this publ ication are subject to change without notice. This pub lication supersedes
and replaces all information previously supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical
components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics.