I Single Timer

LM555/ I SINGLE TIMER SINGLE TIMER The LM555/I is a highly stable controller capable of producing accurate timing pulses. With monostable operation, t...

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LM555/I

SINGLE TIMER

SINGLE TIMER

8 DIP

The LM555/I is a highly stable controller capable of producing accurate timing pulses. With monostable operation, the time delay is controlled by one external and one capacitor. With astable operation, the frequency and duty cycle are accurately controlled with two external resistors and one capacitor.

FEATURES • • • • •

High Current Drive Capability (= 200mA) Adjustable Duty Cycle Temperature Stability of 0.005%/°C Timing From µSec To Hours Turn Off Time Less Than 2µSec

8 SOP

APPLICATIONS • • • •

Precision Timing Pulse Generation Time Delay Generation Sequential Timing

BLOCK DIAGRAM

ORDERING INFORMATION Device

Package

LM555CN LM555CM LM555CIN LM555CIM

8 DIP 8 SOP 8 DIP 8 SOP

Operating Temperature 0 ~ +70°C -40 ~ +85°C

Rev. B

1999 Fairchild Semiconductor Corporation

LM555/I

SINGLE TIMER

ABSOLUTE MAXIMUM RATINGS

(TA = 25°C)

Characteristic Supply Voltage Lead Temperature (soldering 10sec) Power Dissipation Operating Temperature Range LM555C LM555CI Storage Temperature Range

Symbol

Value

VCC TLEAD

16 300

PD

600 0 ~ + 70 - 40 ~ + 85 - 65 ~ + 150

TOPR TSTG

Unit V °C mW °C °C °C

ELECTRICAL CHARACTERISTICS (TA = 25°C, VCC = 5 ~ 15V, unless otherwise specified) Characteristic Supply Voltage Supply Current ∗ (low stable) 1

Symbol

ICC

∗Timing Error (Monostable) 2 Initial Accuracy Drift with Temperature Drift with Supply Voltage

ACCUR ∆t/∆T ∆t/∆VCC

∗Timing Error (astable) 2 Intial Accuracy Drift with Temperature Drift with Supply Voltage

ACCUR ∆t/∆T ∆t/∆VCC

Control Voltage

VC

Threshold Voltage

VTH

∗ Threshold Current Trigger Voltage Trigger Voltage Trigger Current

VTR VTR ITR

Reset Voltage Reset Current

VRST IRST

3

Test Conditions

Typ

Max

Unit

VCC = 5V, RL = ∞

3

16 6

V mA

VCC = 15V, RL = ∞

7.5

15

mA

RA = 1KΩ to 100KΩ C = 0.1µF

1.0 50 0.1

3.0

% ppm/°C %/V

VCC

Min 4.5

RA = 1KΩ to 100KΩ C = 0.1µF

0.5

% ppm/°C %/V

2.25 150 0.3 10.0 3.33 10.0 3.33 0.1

11.0 4.0

V V V V

0.25

µA V V

VCC = 15V VCC = 5V VCC = 15 V VCC = 5V

9.0 2.6

VCC = 5V VCC = 15V VTR = 0V

1.1 4.5

1.67 5 0.01

2.2 5.6 2.0

0.4

0.7 0.1

1.0 0.4

ITH

µA V mA

LM555/I

SINGLE TIMER

ELECTRICAL CHARACTERISTICS (TA = 25°C, VCC = 5 ~ 15V, unless otherwise specified) Characteristic

Low Output Voltage

High Output Voltage

Rise Time of Output Fall Time of Output Discharge Leakage Current

Symbol

VOL

VOH

tR tF ILKG

Test Conditions VCC = 15V ISINK = 10mA ISINK = 50mA VCC = 5V ISINK = 5mA VCC = 15V ISOURCE = 200mA ISOURCE = 100mA VCC = 5V ISOURCE = 100mA

Min

12.75 2.75

Typ

Max

Unit

0.06 0.3

0.25 0.75

V V

0.05

0.35

V

12.5 13.3

V V

3.3 100 100 20

V ns ns nA

100

Notes: 1. Supply current when output is high is typically 1mA less at VCC = 5V 2. Tested at VCC = 5.0V and VCC = 15V 3. This will determine maximum value of RA + RB for 15V operation, the max. total R = 20MΩ, and for 5V operation the max. total R = 6.7MΩ

APPLICATION CIRCUIT

LM555/I

SINGLE TIMER

APPLICATION NOTE The application circuit shows astable mode. Pin 6 (threshold) is tied to Pin 2 (trigger) and Pin 4 (reset) is tied to VCC (Pin 8). The external capacitor C1 of Pin 6 and Pin 2 charges through RA, RB and discharges through RB only. In the internal circuit of the LM555 one input of the upper comparator is the 2/3 VCC (∗R1 =R2=R3, another input if it If it is connected Pin 6. As soon as charging C1 is higher than 2/3 Vcc, discharge transistor Q1 turns on and C1 discharges to collector of transistor Q1. Therefore, the flip-flop circuit is reset and output is low. One input of lower comparator is the 1/3 VCC, discharge transistor Q1 turn off and C1 charges through RA and RB. Therefore, the flip-flop circuit is set and output is high. So to say, when C1 charges through RA and R1 output is high and when C1 discharges through RB output is low. The charge time (output is high) T1 is 0.693 (RA+RB) C1 and the discharge time (output is low) T2 is 0.693 (RB C1). CC (In VCC-1/3V = 0.693) VCC-2/3VCC

Thus the total period time T is given by T=T1 +T2 = 0.693 (RA +2RB) C1. Then the frequency of astable mode is given by f=

=1 T

1.44 (RA + 2RB)C1

The duty cycle is given by D.C =

T =2 T

RB RA + 2RB

If you make use of the LM556 you can make two astable modes.

LM555/I

SINGLE TIMER

Astable Operation The LM555 can free run as a mulitivibrator by triggering itself; refer to Fig.2. The output can swing from VDD to GND and have 50 duty cycle square wave. Less than 1% frequency deviation can be observed, over a voltage range of 2 to 5V. f-1/1.4RC

Ο VCC

10KΩ

GND

1

8

2

7

TRIGGER

///

Ο VCC

DISCHARGE •

Ο

ALTERNATE OUTPUT

LM555C Ο

OUTPUT •

THRESHOLD

3

6

4

5

Ο

VCC RESET





Fig. 1. Astable Operation C ///

Monostable Operation The LM555 can be used as a one-short, i.e. monostable multivibrator. Initially, because the inside discharge transistor is on state, external timing capacitor is held to GND potential. Upon application of a negative TRIGGER pulse pin 2, the intern discharge transistor is off state and the voltage across the capacitor increases with time constant T = RAC and OUTPUT goes to high state. When the voltage across the capacitor equals 2/3VCC the inner comparator is reset by THRESHOLD input and the discharge transistor goes to on state, which in turn discharges the capacitor rapidly and drives the OUTPUT to its low state. VCC ( 18V)

Ο

RA 8

1 /// TRIGGER Ο

OUTPUT

RESET Ο

2

7

• DISCHARGE

LM555C 3

6

4

5

THRESHOLD



CONTROL VOLTAGE

OPTION CAPACITOR

C ///

Fig. 2. Monostable Operation



///

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Advance Information

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This datasheet contains the design specifications for product development. Specifications may change in any manner without notice.

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