LMC555 (NS).pdf

May 2006

LMC555

CMOS Timer

General Description

The LMC555 is a CMOS version of the industry standard

555 series general purpose timers. In addition to the stan-

dard package (SOIC, MSOP, and MDIP) the LMC555 is also

available in a chip sized package (8 Bump micro SMD) using

National’s micro SMD package technology. The LMC555

offers the same capability of generating accurate time delays

and frequencies as the LM555 but with much lower power

dissipation and supply current spikes. When operated as a

one-shot, the time delay is precisely controlled by a single

external resistor and capacitor. In the stable mode the oscil-

lation frequency and duty cycle are accurately set by two

external resistors and one capacitor. The use of National

Semiconductor’s LMCMOS ™ process extends both the fre-

quency range and low supply capability.

Features

n Less than 1 mW typical power dissipation at 5V supply

n 3 MHz astable frequency capability

n 1.5V supply operating voltage guaranteed

n Output fully compatible with TTL and CMOS logic at 5V

supply

n Tested to −10 mA, +50 mA output current levels

n Reduced supply current spikes during output transitions

n Extremely low reset, trigger, and threshold currents

n Excellent temperature stability

n Pin-for-pin compatible with 555 series of timers

n Available in 8-pin MSOP Package and 8-Bump micro

SMD package

Pulse Width Modulator

00866915

00866920

Ordering Information

Package

Temperature Range Package Marking

Transport Media

NSC Drawing

Industrial

−40˚C to +85˚C

8-Pin Small Outline (SO)

LMC555CM

Rails

M08A

LMC555CMX

2.5k Units Tape and Reel

8-Pin Mini Small Outline

(MSOP)

LMC555CMM

ZC5

1k Units Tape and Reel

MUA08A

LMC555CMMX

3.5k Units Tape and Reel

8-Pin Molded Dip (MDIP)

LMC555CN

Rails

N08E

8-Bump micro SMD

LMC555CBP

250 Units Tape and Reel

BPA08EFB

LMC555CBPX

3k Units Tape and Reel

8-Bump micro SMD

NOPB

LMC555CTP

F02

250 Units Tape and Reel

TPA08EFA

LMC555CTPX

3k Units Tape and Reel

Note: See Mil-datasheet MNLMC555-X for specifications on the military device LMC555J/883.

LMCMOS ™ is a trademark of National Semiconductor Corp.

DS008669

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Connection Diagrams

8-Pin SOIC, MSOP, MDIP

00866901

Top View

8-Bump micro SMD

00866909

Top View

(Bump Side Down)

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Absolute Maximum Ratings (Notes 2, 3)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

Supply Voltage, V +

Thermal Resistance (

θ JA ) (Note 2)

SO, 8-Pin Small

Outline

169˚C/W

15V

MSOP, 8-Pin

Mini Small

Outline

Input Voltages, V TRIG ,V RES ,V CTRL ,

V THRESH

225˚C/W

−0.3V to V S + 0.3V

MDIP, 8-Pin

Molded Dip

Output Voltages, V O ,V DIS

15V

111˚C/W

Output Current I O ,I DIS

100 mA

8-Bump micro

SMD

Storage Temperature Range

−65˚C to +150˚C

220˚C/W

Soldering Information

MDIP Soldering (10 seconds)

260˚C

Maximum

Allowable Power

Dissipation @ 25˚C

MDIP-8

SOIC, MSOP Vapor Phase (60 sec)

215˚C

1126 mW

SOIC, MSOP Infrared (15 sec)

220˚C

SO-8

740 mW

Note: See AN-450 “Surface Mounting Methods and Their Effect on Product

Reliability” for other methods of soldering surface mount devices.

MSOP-8

555 mW

8 Bump micro

SMD

Operating Ratings (Notes 2, 3)

568 mW

Termperature

Range

−40˚C to +85˚C

Electrical Characteristics (Notes 1, 2)

Test Circuit, T = 25˚C, all switches open, RESET to V S unless otherwise noted

Symbol Parameter

Conditions

Min Typ Max Units

(Limits)

I S

Supply Current

V S = 1.5V

V S =5V

V S = 12V

100

150

250

400

µA

V CTRL

Control Voltage

V S = 1.5V

V S =5V

V S = 12V

0.8

2.9

7.4

1.0

3.3

8.0

1.2

3.8

8.6

V DIS

Discharge Saturation Voltage V S = 1.5V, I DIS =1mA

V S = 5V, I DIS =10mA

150

300

V OL

Output Voltage (Low)

V S = 1.5V, I O =1mA

V S = 5V, I O =8mA

V S = 12V, I O =50mA

0.2

0.3

1.0

0.4

0.6

2.0

V OH

Output Voltage

(High)

V S = 1.5V, I O = −0.25 mA

V S = 5V, I O =−2mA

V S = 12V, I O = −10 mA

1.0

4.4

10.5

1.25

4.7

11.3

V TRIG

Trigger Voltage

V S = 1.5V

V S = 12V

0.4

3.7

0.5

4.0

0.6

4.3

I TRIG

Trigger Current

V S =5V

V RES

Reset Voltage

V S = 1.5V (Note 4)

V S = 12V

0.4

0.7

0.75

1.0

1.1

I RES

Reset Current

V S =5V

I THRESH

Threshold Current

V S =5V

I DIS

Discharge Leakage

V S = 12V

1.0

100

Timing Accuracy

SW 2, 4 Closed

V S = 1.5V

V S =5V

V S = 12V

0.9

1.0

1.1

1.25

1.20

1.25

∆

V S

Timing Shift with Supply

V S =5V ± 1V

0.3

%/V

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Electrical Characteristics (Notes 1, 2)

Test Circuit, T = 25˚C, all switches open, RESET to V S unless otherwise noted (Continued)

Symbol Parameter

Conditions

Min Typ Max Units

(Limits)

∆

Timing Shift with

Temperature

V S =5V

−40˚C

ppm/˚C

≤

+85˚C

f A

Astable Frequency

SW 1, 3 Closed, V S = 12V

4.0

4.8

5.6

kHz

f MAX

Maximum Frequency

Max. Freq. Test Circuit, V S = 5V

3.0

MHz

t R ,t F

Output Rise and

Fall Times

Max. Freq. Test Circuit

V S = 5V, C L =10pF

t PD

Trigger Propagation Delay

V S = 5V, Measure Delay

from Trigger to Output

100

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

functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which

guarantee 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: See AN-450 for other methods of soldering surface mount devices, and also AN-1112 for micro SMD considerations.

Note 4: If the RESET pin is to be used at temperatures of −20˚C and below V S is required to be 2.0V or greater.

Note 5: For device pinout please refer to table 1

Test Circuit (Note 5)

Maximum Frequency Test Circuit (Note 5)

00866902

00866903

TABLE 1. Package Pinout Names vs. Pin Function

Pin Function

Package Pin numbers

8-Pin SO, MSOP, and MDIP

8-Bump micro SMD

GND

Trigger

Outpu t

Reset

Control Voltage

Threshold

Discharge

V +

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Application Information

negative pulse to the reset terminal. The output will then

remain in the low state until a trigger pulse is again applied.

When the reset function is not use, it is recommended that it

be connected to V + to avoid any possibility of false triggering.

Figure 3 is a nomograph for easy determination of RC values

for various time delays.

Note: In monstable operation, the trigger should be driven high before the

end of timing cycle.

MONOSTABLE OPERATION

In this mode of operation, the timer functions as a one-shot

( Figure 1 ). The external capacitor is initially held discharged

by internal circuitry. Upon appli cation of a negative trigger

pulse of less than 1/3 V S to the Trigger terminal, the flip-flop

is set which both releases the short circuit across the capaci-

tor and drives the output high.

00866904

00866911

FIGURE 1. Monostable (One-Shot)

FIGURE 3. Time Delay

The voltage across the capacitor then increases exponen-

tially for a period of t H = 1.1 R A C, which is also the time that

the output stays high, at the end of which time the voltage

equals 2/3 V S . 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 generated in this

mode of operation. Since the charge and the threshold level

of the comparator are both directly proportional to supply

voltage, the timing internal is independent of supply.

ASTABLE OPERATION

If the circuit is connected as shown in Figure 4 (Trigger and

Threshold terminals connected together) it will trigger itself

and free run as a multivibrator. The external capacitor

charges through R A +R B and discharges through R B . Thus

the duty cycle may be precisely set by the ratio of these two

resistors.

00866910

V CC = 5V Top Trace: Input 5 V/Div.

TIME = 0.1 ms/Div. Middle Trace: Output 5 V/Div.

R A = 9.1 k

00866905

Ω

Bottom Trace: Capacitor Voltage 2 V/Div.

FIGURE 4. Astable (Variable Duty Cycle Oscillator)

C = 0.01 µF

FIGURE 2. Monostable Waveforms

In this mode of operation, the capacitor charges and dis-

charges between 1/3 V S and 2/3 V S . As in the triggered

mode, the charge and discharge times, and therefore the

frequency are independent of the supply voltage.

Figure 5 shows the waveform generated in this mode of

operation.

Reset overrides Trigger, which can override threshold.

Therefore the trigger pulse must be shorter than the desired

t H . The minimum pulse width for the Trigger is 20ns, and it is

400ns for the Reset. 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

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