Basic Operation of a 555 Timer

• Threshold• Control Voltage• Trigger• Discharge• Reset• Output

Functional Diagram of 555 Timer

The 555 Timer Connected as a One-shot. Figure 8--49

One-shot Operationof the 555 timer. Figure 8--50

555 Timer as a One Shot

tw = 1.1R1C1 = 1.1(2000)(1F) = 2.2ms

555 Timer as a One Shot waveform

Astable operation of 555 Timer

tH = .7 (R1+R2)C1 =2.1ms tL = .7R2C1 = 0.7ms

Astable operation of 555 Timer

Astable operation of 555 Timer

Astable operation of 555 Timer

%1002

2

44.1

21

21

121

RR

RRDutyCycle

CRRf

Less Than 50% Duty Cycle. Figure 8--54

Example 8-14. Figure 8--55

%5.59%1004.92.2

7.42.2%100

2

64.5022.04.92.2

44.1

2

44.1

21

21

121

kk

kk

RR

RRDutyCycle

kHzFkkCRR

f

Astable operation of 555 Timer waveform

555 Timer Datasheet

555 Timer Datasheet