LM555
Timer
General Description
The LM555 is a highly stable device for generating accurate
time delays or oscillation. Additional terminals are provided
for triggering or resetting if desired. In the time delay mode of
operation, the time is precisely controlled by one external re-
sistor and capacitor. For astable operation as an oscillator,
the free running frequency and duty cycle are accurately
controlled with two external resistors and one capacitor. The
circuit may be triggered and reset on falling waveforms, and
the output circuit can source or sink up to 200mA or drive
TTL circuits.
Features
n
Direct replacement for SE555/NE555
n
Timing from microseconds through hours
n
Operates in both astable and monostable modes
n
Adjustable duty cycle
n
Output can source or sink 200 mA
n
Output and supply TTL compatible
n
Temperature stability better than 0.005% per C
n
Normally on and normally off output
n
Available in 8-pin MSOP package
Applications
n
Precision timing
n
Pulse generation
n
Sequential timing
n
Time delay generation
n
Pulse width modulation
n
Pulse position modulation
n
Linear ramp generator
Schematic Diagram
DS007851-1
February 2000
LM555
T
imer
2000 National Semiconductor Corporation
DS007851
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Connection Diagram
Ordering Information
Package
Part Number
Package Marking
Media Transport
NSC Drawing
8-Pin SOIC
LM555CM
LM555CM
Rails
M08A
LM555CMX
LM555CM
2.5k Units Tape and Reel
8-Pin MSOP
LM555CMM
Z55
1k Units Tape and Reel
MUA08A
LM555CMMX
Z55
3.5k Units Tape and Reel
8-Pin MDIP
LM555CN
LM555CN
Rails
N08E
Dual-In-Line, Small Outline
and Molded Mini Small Outline Packages
DS007851-3
Top View
LM555
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2
Absolute Maximum Ratings
(Note 2)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
+18V
Power Dissipation (Note 3)
LM555CM, LM555CN
1180 mW
LM555CMM
613 mW
Operating Temperature Ranges
LM555C
0C to +70C
Storage Temperature Range
-65C to +150C
Soldering Information
Dual-In-Line Package
Soldering (10 Seconds)
260C
Small Outline Packages
(SOIC and MSOP)
Vapor Phase (60 Seconds)
215C
Infrared (15 Seconds)
220C
See AN-450 "Surface Mounting Methods and Their Effect
on Product Reliability" for other methods of soldering
surface mount devices.
Electrical Characteristics
(Notes 1, 2)
(T
A
= 25C, V
CC
= +5V to +15V, unless othewise specified)
Parameter
Conditions
Limits
Units
LM555C
Min
Typ
Max
Supply Voltage
4.5
16
V
Supply Current
V
CC
= 5V, R
L
=
V
CC
= 15V, R
L
=
(Low State) (Note 4)
3
10
6
15
mA
Timing Error, Monostable
Initial Accuracy
1
%
Drift with Temperature
R
A
= 1k to 100k
,
50
ppm/C
C = 0.1F, (Note 5)
Accuracy over Temperature
1.5
%
Drift with Supply
0.1
%/V
Timing Error, Astable
Initial Accuracy
2.25
%
Drift with Temperature
R
A
, R
B
= 1k to 100k
,
150
ppm/C
C = 0.1F, (Note 5)
Accuracy over Temperature
3.0
%
Drift with Supply
0.30
%/V
Threshold Voltage
0.667
x V
CC
Trigger Voltage
V
CC
= 15V
5
V
V
CC
= 5V
1.67
V
Trigger Current
0.5
0.9
A
Reset Voltage
0.4
0.5
1
V
Reset Current
0.1
0.4
mA
Threshold Current
(Note 6)
0.1
0.25
A
Control Voltage Level
V
CC
= 15V
V
CC
= 5V
9
2.6
10
3.33
11
4
V
Pin 7 Leakage Output High
1
100
nA
Pin 7 Sat (Note 7)
Output Low
V
CC
= 15V, I
7
= 15mA
180
mV
Output Low
V
CC
= 4.5V, I
7
= 4.5mA
80
200
mV
LM555
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Electrical Characteristics
(Notes 1, 2) (Continued)
(T
A
= 25C, V
CC
= +5V to +15V, unless othewise specified)
Parameter
Conditions
Limits
Units
LM555C
Min
Typ
Max
Output Voltage Drop (Low)
V
CC
= 15V
I
SINK
= 10mA
0.1
0.25
V
I
SINK
= 50mA
0.4
0.75
V
I
SINK
= 100mA
2
2.5
V
I
SINK
= 200mA
2.5
V
V
CC
= 5V
I
SINK
= 8mA
V
I
SINK
= 5mA
0.25
0.35
V
Output Voltage Drop (High)
I
SOURCE
= 200mA, V
CC
= 15V
12.5
V
I
SOURCE
= 100mA, V
CC
= 15V
12.75
13.3
V
V
CC
= 5V
2.75
3.3
V
Rise Time of Output
100
ns
Fall Time of Output
100
ns
Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.
Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is func-
tional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guar-
antee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is
given, however, the typical value is a good indication of device performance.
Note 3: For operating at elevated temperatures the device must be derated above 25C based on a +150C maximum junction temperature and a thermal resistance
of 106C/W (DIP), 170C/W (S0-8), and 204C/W (MSOP) junction to ambient.
Note 4: Supply current when output high typically 1 mA less at V
CC
= 5V.
Note 5: Tested at V
CC
= 5V and V
CC
= 15V.
Note 6: This will determine the maximum value of R
A
+ R
B
for 15V operation. The maximum total (R
A
+ R
B
) is 20M
.
Note 7: No protection against excessive pin 7 current is necessary providing the package dissipation rating will not be exceeded.
Note 8: Refer to RETS555X drawing of military LM555H and LM555J versions for specifications.
LM555
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Typical Performance Characteristics
Minimuim Pulse Width
Required for Triggering
DS007851-4
Supply Current vs.
Supply Voltage
DS007851-19
High Output Voltage vs.
Output Source Current
DS007851-20
Low Output Voltage vs.
Output Sink Current
DS007851-21
Low Output Voltage vs.
Output Sink Current
DS007851-22
Low Output Voltage vs.
Output Sink Current
DS007851-23
LM555
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