LM555QML
LM555QML Timer
Literature Number: SNOSAP2B
LM555QML
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
resistor 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
nDirect replacement for SE555/NE555
nTiming from microseconds through hours
nOperates in both astable and monostable modes
nAdjustable duty cycle
nOutput can source or sink 200 mA
nOutput and supply TTL compatible
nTemperature stability better than 0.005% per ˚C
nNormally on and normally off output
Applications
nPrecision timing
nPulse generation
nSequential timing
nTime delay generation
nPulse width modulation
nPulse position modulation
nLinear ramp generator
Ordering Information
NS Part Number SMD Part Number NS Package Number Package Description
LM555H/883 H08A 8LD Metal Can
LM555J/883 J08A 8LD Ceramic Dip
Connection Diagrams
Dual-In-Line Package Metal Can Package
20149803
Top View
20149833
Top View
July 2006
LM555QML Timer
© 2006 National Semiconductor Corporation DS201498 www.national.com
Schematic Diagram
20149801
LM555QML
www.national.com 2
Absolute Maximum Ratings (Note 1)
Supply Voltage +18V
Power Dissipation (Note 2)
Metal Can 760 mW
CERDIP 1180 mW
Operating Temperature Range −55˚C ≤T
A
≤+125˚C
Maximum Junction Temperature (T
Jmax)
+150˚C
Storage Temperature Range −65˚C ≤T
A
≤+150˚C
Soldering Information (Soldering 10 Seconds) 260˚C
Thermal Resistance
θ
JA
CERDIP Still Air 125˚C/W
CERDIP 500LF / Min Air Flow 71˚C/W
Metal Can Still Air 176˚C/W
Metal Can 500LF / Min Air Flow 96˚C/W
θ
JC
CERDIP 20˚C/W
Metal Can 42˚C/W
ESD Tolerance (Note 3) 500V
Quality Conformance Inspection
Mil-Std-883, Method 5005 - Group A
Subgroup Description Temp ˚C
1 Static tests at 25
2 Static tests at 125
3 Static tests at -55
4 Dynamic tests at 25
5 Dynamic tests at 125
6 Dynamic tests at -55
7 Functional tests at 25
8A Functional tests at 125
8B Functional tests at -55
9 Switching tests at 25
10 Switching tests at 125
11 Switching tests at -55
12 Settling time at 25
13 Settling time at 125
14 Settling time at -55
LM555QML
www.national.com3
Electrical Characteristics
DC Parameters
The following conditions apply to all the following parameters, unless otherwise specified.
DC: +5V ≤V
CC
≤+15V
Symbol Parameter Conditions Notes Min Max Unit Sub-
groups
I
CCL
Supply Current Low State V
CC
= 5V, R
L
=∞5.0 mA 1
V
CC
= 15V, R
L
=∞12.0 mA 1
V
CC
= 18V, R
L
=∞,
V
2
=V
6
= 18V 18.5 mA 1
I
L7
Leakage Current Pin 7 V
CC
= 18V, V
7
= 18V,
V
2
=V
6
=0 100 nA 1
V
Sat
Saturation Voltage Pin 7 V
CC
= 15V, I
7
= 15mA,
V
2
=V
6
= 12V (Note 6) 240 mV 1
V
CC
= 4.5V, I
7
= 4.5mA (Note 6) 80 mV 1
V
CO
Control Voltage V
CC
= 5V,
V
2
=V
6
=4V 2.9 3.8 V 1, 2, 3
V
CC
= 15V,
V
2
=V
6
= 12V 9.6 10.4 V 1, 2, 3
V
Th
Threshold Voltage 9.5 10.5 V 1
I
Th
Threshold Current V
6
=V
Th
,V
2
= 7.5V,
V
Th
=V
Th
Test Measured Value (Note 7) 250 nA 1
I
Trig
Trigger Current V
2
= 0 500 nA 1
V
Trig
Trigger Voltage V
CC
= 15V 4.8 5.2 V 1
3.0 6.0 V 2, 3
V
CC
= 5V (Note 4) 1.45 1.9 V 1, 2, 3
I
Reset
Reset Current V
2
=V
6
= Gnd 0.4 mA 1
V
Reset
Reset Voltage 0.4 1.0 V 1
V
OL
Output Voltage Drop Low V
CC
= 5V, I
Sink
= +8mA,
V
7
= 5V, V
6
=5V 250 mV 1, 2, 3
V
CC
= 15V, I
Sink
= +10mA,
V
2
=V
6
= 15V
150 mV 1
250 mV 2, 3
V
CC
= 15V, I
Sink
= +50mA,
V
2
=V
6
= 15V
500 mV 1
800 mV 2, 3
V
CC
= 15V, I
Sink
= +85mA,
V
2
=V
6
= 15V 2.2 V 1,2,3
V
OH
Output Voltage Drop High V
CC
= 15V, I
Source
= 85mA 13 V 1
12.75 V 2, 3
V
CC
= 5V, I
Source
= 85mA 3 V 1
2.75 V 2, 3
Aƒ A Stable Frequency (Note 5) 45 51 KHz 1
tE Timing Error V
CC
= 5V (Note 5) ±2 % 1, 2, 3
V
CC
= 15V, 1KΩ≤R
A
≤100KΩ,
Timing error decreases with an
increase in V
CC
(Note 5) ±2 % 1, 2, 3
∆tE/∆V
CC
Timing Drift with Supply 5V ≤V
CC
≤15V (Note 5) 0.2 % / V 1, 2, 3
LM555QML
www.national.com 4
Electrical Characteristics (Continued)
AC Parameters
The following conditions apply to all the following parameters, unless otherwise specified.
AC: +5V ≤V
CC
≤+15V
Symbol Parameter Conditions Notes Min Max Unit Sub-
groups
tR Rise Time V
Trig
= 5V (Note 5) 250 nS 9, 10
(Note 5) 400 nS 11
tF Fall Time V
Trig
= 5V (Note 5) 250 nS 9, 10
(Note 5) 400 nS 11
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed
specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJmax (maximum junction temperature), θJA (package
junction to ambient thermal resistance), and TA(ambient temperature). The maximum allowable power dissipation at any temperature is PDmax =(T
Jmax -T
A)/θJA
or the number given in the Absolute Maximum Ratings, whichever is lower.
Note 3: Human body model, 1.5KΩin series with 100pF.
Note 4: Guaranteed by tests at VCC = 15V.
Note 5: Guaranteed parameter, not tested.
Note 6: No protection against excessive pin 7 current is necessary providing the package dissipation rating will not be exceeded.
Note 7: This will determine the maximum value of RA+R
Bfor 15V operation. The maximum total (RA+R
B)is20MΩ.
LM555QML
www.national.com5
Typical Performance Characteristics
Minimum Pulse Width
Required for Triggering
Supply Current vs.
Supply Voltage
20149804 20149819
High Output Voltage vs.
Output Source Current
Low Output Voltage vs.
Output Sink Current
20149820 20149821
Low Output Voltage vs.
Output Sink Current
Low Output Voltage vs.
Output Sink Current
20149822 20149823
LM555QML
www.national.com 6
Typical Performance Characteristics (Continued)
Output Propagation Delay vs.
Voltage Level of Trigger Pulse
Output Propagation Delay vs.
Voltage Level of Trigger Pulse
20149824 20149825
Discharge Transistor (Pin 7)
Voltage vs. Sink Current
Discharge Transistor (Pin 7)
Voltage vs. Sink Current
20149826 20149827
LM555QML
www.national.com7
Applications Information
MONOSTABLE OPERATION
In this mode of operation, the timer functions as a one-shot
(Figure 1). The external capacitor is initially held discharged
by a transistor inside the timer. Upon application of a nega-
tive trigger pulse of less than 1/3 V
CC
to pin 2, the flip-flop is
set which both releases the short circuit across the capacitor
and drives the output high.
The voltage across the capacitor then increases exponen-
tially for a period of t = 1.1 R
A
C, at the end of which time the
voltage equals 2/3 V
CC
. The comparator then resets the
flip-flop which in turn discharges the capacitor and drives the
output to its low state. Figure 2 shows the waveforms gen-
erated in this mode of operation. Since the charge and the
threshold level of the comparator are both directly propor-
tional to supply voltage, the timing interval is independent of
supply.
During the timing cycle when the output is high, the further
application of a trigger pulse will not effect the circuit so long
as the trigger input is returned high at least 10µs before the
end of the timing interval. However the circuit can be reset
during this time by the application of a negative pulse to the
reset terminal (pin 4). The output will then remain in the low
state until a trigger pulse is again applied.
When the reset function is not in use, it is recommended that
it be connected to V
CC
to avoid any possibility of false
triggering.
Figure 3 is a nomograph for easy determination of R, C
values for various time delays.
NOTE: In monostable operation, the trigger should be driven
high before the end of timing cycle.
ASTABLE OPERATION
If the circuit is connected as shown in Figure 4 (pins 2 and 6
connected) it will trigger itself and free run as a multivibrator.
The external capacitor charges through R
A
+R
B
and dis-
charges through R
B
. Thus the duty cycle may be precisely
set by the ratio of these two resistors.
In this mode of operation, the capacitor charges and dis-
charges between 1/3 V
CC
and 2/3 V
CC
. As in the triggered
mode, the charge and discharge times, and therefore the
frequency are independent of the supply voltage.
20149805
FIGURE 1. Monostable
20149806
VCC = 5V Top Trace: Input 5V/Div.
TIME = 0.1 ms/DIV. Middle Trace: Output 5V/Div.
RA= 9.1kΩBottom Trace: Capacitor Voltage 2V/Div.
C = 0.01µF
FIGURE 2. Monostable Waveforms
20149807
FIGURE 3. Time Delay
20149808
FIGURE 4. Astable
LM555QML
www.national.com 8
Applications Information (Continued)
Figure 5 shows the waveforms generated in this mode of
operation.
The charge time (output high) is given by:
t
1
= 0.693 (R
A
+R
B
)C
And the discharge time (output low) by:
t
2
= 0.693 (R
B
)C
Thus the total period is:
T=t
1
+t
2
= 0.693 (R
A
+2R
B
)C
The frequency of oscillation is:
Figure 6 may be used for quick determination of these RC
values.
The duty cycle is:
FREQUENCY DIVIDER
The monostable circuit of Figure 1 can be used as a fre-
quency divider by adjusting the length of the timing cycle.
Figure 7 shows the waveforms generated in a divide by three
circuit.
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
8shows the circuit, and in Figure 9 are some waveform
examples.
20149809
VCC = 5V Top Trace: Output 5V/Div.
TIME = 20µs/DIV. Bottom Trace: Capacitor Voltage 1V/Div.
RA= 3.9kΩ
RB=3kΩ
C = 0.01µF
FIGURE 5. Astable Waveforms
20149810
FIGURE 6. Free Running Frequency
20149811
VCC = 5V Top Trace: Input 4V/Div.
TIME = 20µs/DIV. Middle Trace: Output 2V/Div.
RA= 9.1kΩBottom Trace: Capacitor 2V/Div.
C = 0.01µF
FIGURE 7. Frequency Divider
20149812
FIGURE 8. Pulse Width Modulator
LM555QML
www.national.com9
Applications Information (Continued)
PULSE POSITION MODULATOR
This application uses the timer connected for astable opera-
tion, as in Figure 10, with a modulating signal again applied
to the control voltage terminal. The pulse position varies with
the modulating signal, since the threshold voltage and hence
the time delay is varied. Figure 11 shows the waveforms
generated for a triangle wave modulation signal.
LINEAR RAMP
When the pullup resistor, R
A
, in the monostable circuit is
replaced by a constant current source, a linear ramp is
generated. Figure 12 shows a circuit configuration that will
perform this function.
Figure 13 shows waveforms generated by the linear ramp.
The time interval is given by:
V
BE
.0.6V
20149813
VCC = 5V Top Trace: Modulation 1V/Div.
TIME = 0.2 ms/DIV. Bottom Trace: Output Voltage 2V/Div.
RA= 9.1kΩ
C = 0.01µF
FIGURE 9. Pulse Width Modulator
20149814
FIGURE 10. Pulse Position Modulator
20149815
VCC = 5V Top Trace: Modulation Input 1V/Div.
TIME = 0.1 ms/DIV. Bottom Trace: Output 2V/Div.
RA= 3.9kΩ
RB=3kΩ
C = 0.01µF
FIGURE 11. Pulse Position Modulator
20149816
FIGURE 12.
LM555QML
www.national.com 10
Applications Information (Continued)
50% DUTY CYCLE OSCILLATOR
For a 50% duty cycle, the resistors R
A
and R
B
may be
connected as in Figure 14. The time period for the output
high is the same as previous, t
1
= 0.693 R
A
C. For the output
low it is t
2
=
Thus the frequency of oscillation is
Note that this circuit will not oscillate if R
B
is greater than 1/2
R
A
because the junction of R
A
and R
B
cannot bring pin 2
down to 1/3 V
CC
and trigger the lower comparator.
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.
20149817
VCC = 5V Top Trace: Input 3V/Div.
TIME = 20µs/DIV. Middle Trace: Output 5V/Div.
R1= 47kΩBottom Trace: Capacitor Voltage 1V/Div.
R2= 100kΩ
RE= 2.7 kΩ
C = 0.01 µF
FIGURE 13. Linear Ramp
20149818
FIGURE 14. 50% Duty Cycle Oscillator
LM555QML
www.national.com11
Revision History
Date
Released
Revision Section Originator Changes
08/04/05 A New Release to corporate format L. Lytle 1 MDS datasheet converted into once
datasheet in the corporate format. Removed
drift endpoints since not performed on 883
product. MNLM555-X Rev 0B0 to be
archived
04/10/06 B Ordering Information Table R. Malone NS Package Number and Description was
referenced incorrectly. Revision A will be
Archived.
07/25/06 C Applications Information, page 8 R. Malone Correct a typo in the paragraph after figure
1 (change the word internal to interval) to
reflect same change made to Commercial
data sheet. Revision B will be Archived.
LM555QML
www.national.com 12
Physical Dimensions inches (millimeters) unless otherwise noted
8LD Ceramic Dip Package (J)
NS Package Number J08A
LM555QML
www.national.com13
Physical Dimensions inches (millimeters) unless otherwise noted (Continued)
8LD Metal Can Package (H)
NS Package Number H08A
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
LIFE SUPPORT POLICY
NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body, or
(b) support or sustain life, and whose failure to perform when
properly used in accordance with instructions for use
provided in the labeling, can be reasonably expected to result
in a significant injury to the user.
2. A critical component is any component of a life support
device or system whose failure to perform can be reasonably
expected to cause the failure of the life support device or
system, or to affect its safety or effectiveness.
BANNED SUBSTANCE COMPLIANCE
National Semiconductor follows the provisions of the Product Stewardship Guide for Customers (CSP-9-111C2) and Banned Substances
and Materials of Interest Specification (CSP-9-111S2) for regulatory environmental compliance. Details may be found at:
www.national.com/quality/green.
Lead free products are RoHS compliant.
National Semiconductor
Americas Customer
Support Center
Email: new.feedback@nsc.com
Tel: 1-800-272-9959
National Semiconductor
Europe Customer Support Center
Fax: +49 (0) 180-530 85 86
Email: europe.support@nsc.com
Deutsch Tel: +49 (0) 69 9508 6208
English Tel: +44 (0) 870 24 0 2171
Français Tel: +33 (0) 1 41 91 8790
National Semiconductor
Asia Pacific Customer
Support Center
Email: ap.support@nsc.com
National Semiconductor
Japan Customer Support Center
Fax: 81-3-5639-7507
Email: jpn.feedback@nsc.com
Tel: 81-3-5639-7560
www.national.com
LM555QML Timer
IMPORTANT NOTICE
Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements,
and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should
obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are
sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment.
TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard
warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where
mandated by government requirements, testing of all parameters of each product is not necessarily performed.
TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and
applications using TI components. To minimize the risks associated with customer products and applications, customers should provide
adequate design and operating safeguards.
TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right,
or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information
published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a
warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual
property of the third party, or a license from TI under the patents or other intellectual property of TI.
Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied
by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive
business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional
restrictions.
Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all
express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not
responsible or liable for any such statements.
TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably
be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing
such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and
acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products
and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be
provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in
such safety-critical applications.
TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are
specifically designated by TI as military-grade or "enhanced plastic."Only products designated by TI as military-grade meet military
specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at
the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use.
TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are
designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated
products in automotive applications, TI will not be responsible for any failure to meet such requirements.
Following are URLs where you can obtain information on other Texas Instruments products and application solutions:
Products Applications
Audio www.ti.com/audio Communications and Telecom www.ti.com/communications
Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers
Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps
DLP®Products www.dlp.com Energy and Lighting www.ti.com/energy
DSP dsp.ti.com Industrial www.ti.com/industrial
Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical
Interface interface.ti.com Security www.ti.com/security
Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense
Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive
Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video
RFID www.ti-rfid.com
OMAP Mobile Processors www.ti.com/omap
Wireless Connectivity www.ti.com/wirelessconnectivity
TI E2E Community Home Page e2e.ti.com
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright ©2011, Texas Instruments Incorporated
