TS3V556 Ver la hoja de datos (PDF) - STMicroelectronics

Número de pieza

componentes Descripción

Fabricante

TS3V556

3V LOW POWER DUAL TIMERS

STMicroelectronics 

TS3V556

ASTABLE OPERATION

When the circuit is connected as shown in

figure 4 , it triggers itself and free runs as a

multivibrator. The external capacitor charges

through RA and RB and discharges through RB only.

Thus the duty cycle may be precisely set by the ra-

tio of these two resistors.

In the astable mode of operation, C charges and

discharges between 1/3 VCC and 2/3 VCC. As in the

triggered mode, the charge and discharge times

and therefore frequency, are independent of the

supply voltage.

Figure 5 shows actual waveforms generated in this

mode of operation.

The charge time (output HIGH) is given by :

t1 = 0.693 (RA + RB) C

and the discharge time (output LOW) by :

t2 = 0.693 (RB) C

Thus the total period T is given by :

T = t1 + t2 = 0.693 (RA + 2RB) C

The frequency of oscillation is then :

f = 1 = 1.44

T (RA + 2RB) C

The duty cycle is given by : D = RB

RA + 2RB

Figure 4

VC C

Reset

Figure 5

t = 0.5 ms / div

OUTPUT VOLTAGE = 5.0V/div

RA

Out

TS3V556

RB

Control

Voltage

0.01 µF

C

CAPACITOR VOLTAGE = 1.0V/div

RA = RB = 4.8 k , C = 0.1 F , R L = 1.0k

6/8

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