NE555
SA555 - SE555
General-purpose single bipolar timers
Features
■
■
■
■
■
■
■
■
Low turn-off time
Maximum operating frequency greater than
500 kHz
Timing from microseconds to hours
Operates in both astable and monostable
modes
Output can source or sink up to 200 mA
Adjustable duty cycle
TTL compatible
Temperature stability of 0.005% per °C
D
SO8
(Plastic micropackage)
N
DIP8
(Plastic package)
Description
The NE555, SA555, and SE555 monolithic timing
circuits are highly stable controllers capable of
producing accurate time delays or oscillation. In
the time delay mode of operation, the time is
precisely controlled by one external resistor and
capacitor. For a stable operation 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 200 mA.
Pin connections
(top view)
1
2
3
4
8
7
6
5
1 - GND
2 - Trigger
3
- Output
4 - Reset
5 - Control voltage
6 - Threshold
7 - Discharge
8 - V
CC
January 2012
Doc ID 2182 Rev 6
1/20
www.st.com
20
Schematic diagrams
NE555 - SA555 - SE555
1
Schematic diagrams
Figure 1.
Block diagram
V
CC
+
5kΩ
COMP
THRESHOLD
CONTROL VOLTAGE
R
FLIP-FLOP
5kΩ
COMP
TRIGGER
DISCHARGE
Q
OUT
S
INHIBIT/
RESET
5kΩ
RESET
S
Figure 2.
Schematic diagram
2/20
Doc ID 2182 Rev 6
NE555 - SA555 - SE555
Absolute maximum ratings and operating conditions
2
Absolute maximum ratings and operating conditions
Table 1.
Symbol
V
CC
I
OUT
R
thja
Supply voltage
Output current (sink & source)
Thermal resistance junction to ambient
(1)
DIP8
SO-8
Thermal resistance junction to case
(1)
DIP8
SO-8
Human body model (HBM)
(2)
ESD
Machine model (MM)
(3)
Charged device model (CDM)
(4)
Latch-up immunity
T
LEAD
T
j
T
stg
Lead temperature (soldering 10 seconds)
Junction temperature
Storage temperature range
Absolute maximum ratings
Parameter
Value
18
±225
85
125
41
40
1000
100
1500
200
260
150
-65 to 150
mA
°C
°C
°C
V
Unit
V
mA
°C/W
R
thjc
°C/W
1. Short-circuits can cause excessive heating. These values are typical.
2. Human body model: a 100 pF capacitor is charged to the specified voltage, then discharged through a
1.5 kΩ resistor between two pins of the device. This is done for all couples of connected pin combinations
while the other pins are floating.
3.
Machine model: a 200 pF capacitor is charged to the specified voltage, then discharged directly between
two pins of the device with no external series resistor (internal resistor < 5
Ω).
This is done for all couples of
connected pin combinations while the other pins are floating.
4. Charged device model: all pins and the package are charged together to the specified voltage and then
discharged directly to the ground through only one pin. This is done for all pins.
Table 2.
Operating conditions
Parameter
Supply voltage
NE555
SA555
SE555
Maximum input voltage
Output current (sink and source)
Operating free air temperature range
NE555
SA555
SE555
Value
Unit
Symbol
V
CC
4.5 to 16
4.5 to 16
4.5 to 18
V
CC
±200
0 to 70
-40 to 105
-55 to 125
V
V
th
, V
trig
,
V
cl
, V
reset
I
OUT
V
mA
T
oper
°C
Doc ID 2182 Rev 6
3/20
Electrical characteristics
NE555 - SA555 - SE555
3
Table 3.
Symbol
Electrical characteristics
T
amb
= +25° C, V
CC
= +5 V to +15 V (unless otherwise specified)
SE555
Parameter
Min.
Supply current (R
L
=
∝)
Low state
V
CC
= +5 V
V
CC
= +15 V
High state
V
CC
= +5 V
Timing error (monostable)
(R
A
= 2 kΩ to 100 kΩ, C = 0.1
μF)
Initial accuracy
(1)
Drift with temperature
Drift with supply voltage
Timing error (astable)
(R
A
,
R
B
= 1 kΩ to 100 kΩ, C = 0.1
μF,
V
CC
= +15 V)
Initial accuracy
(1)
Drift with temperature
Drift with supply voltage
V
CL
Control voltage level
V
CC
= +15 V
V
CC
= +5 V
Threshold voltage
V
CC
= +15 V
V
CC
= +5 V
Threshold current
(2)
Trigger voltage
V
CC
= +15 V
V
CC
= +5 V
Trigger current (V
trig
= 0 V)
Reset voltage
(3)
Reset current
V
reset
= +0.4 V
V
reset
= 0 V
Low level output voltage
V
CC
= +15 VI
O(sink)
= 10 mA
I
O(sink)
= 50 mA
I
O(sink)
= 100 mA
I
O(sink)
= 200 mA
V
CC
= +5 V I
O(sink)
= 8 mA
I
O(sink)
= 5 mA
0.4
4.8
1.45
9.6
2.9
9.4
2.7
Typ.
Max.
Min.
Typ.
Max.
NE555 - SA555
Unit
I
CC
3
10
2
5
12
3
10
2
6
15
mA
0.5
30
0.05
2
100
0.2
1
50
0.1
3
0.5
%
ppm/°C
%/V
1.5
90
0.15
10
3.33
10
3.33
0.1
5
1.67
0.5
0.7
0.1
0.4
0.1
0.4
2
2.5
0.1
0.05
10.4
3.8
10.6
4
0.25
5.2
1.9
0.9
1
0.4
1
0.15
0.5
2.2
0.25
0.2
0.4
4.5
1.1
9
2.6
8.8
2.4
2.25
150
0.3
10
3.33
10
3.33
0.1
5
1.67
0.5
0.7
0.1
0.4
0.1
0.4
2
2.5
0.3
0.25
11
4
11.2
4.2
0.25
5.6
2.2
2.0
1
0.4
1.5
0.25
0.75
2.5
0.4
0.35
%
ppm/°C
%/V
V
V
th
I
th
V
trig
I
trig
V
reset
I
reset
V
µA
V
µA
V
mA
V
OL
V
4/20
Doc ID 2182 Rev 6
NE555 - SA555 - SE555
Table 3.
Symbol
Electrical characteristics
T
amb
= +25° C, V
CC
= +5 V to +15 V (unless otherwise specified) (continued)
SE555
Parameter
Min.
High level output voltage
V
CC
= +15 VI
O(sink)
= 200 mA
I
O(sink)
= 100 mA
V
CC
= +5 V I
O(sink)
= 100 mA
Discharge pin leakage current
(output high) V
dis
= 10 V
Discharge pin saturation voltage
(output low)
(4)
V
CC
= +15V, I
dis
= 15 mA
V
CC
= +5V, I
dis
= 4.5 mA
Output rise time
Output fall time
Turn off time
(5)
(V
reset
= V
CC
)
Typ.
Max.
Min.
Typ.
Max.
NE555 - SA555
Unit
V
OH
13
3
12.5
13.3
3.3
20
100
12.7
5
2.75
12.5
13.3
3.3
20
100
V
I
dis(off)
nA
V
dis(sat)
180
80
100
100
0.5
480
200
200
200
180
80
100
100
0.5
480
200
300
300
mV
t
r
t
f
t
off
ns
µs
1. Tested at V
CC
= +5 V and V
CC
= +15 V.
2. This will determine the maximum value of R
A
+ R
B
for 15 V operation. The maximum total (R
A
+ R
B
) is 20 MΩ for +15 V
operation and
3.5
MΩ for +5 V operation.
3.
Specified with trigger input high.
4. No protection against excessive pin 7 current is necessary, providing the package dissipation rating is not exceeded.
5. Time measured from a positive pulse (from 0 V to 0.8 x V
CC
) on the threshold pin to the transition from high to low on the
output pin. Trigger is tied to threshold.
Doc ID 2182 Rev 6
5/20
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