UPC1555C Просмотр технического описания (PDF) - NEC => Renesas Technology

Номер в каталоге

Компоненты Описание

производитель

UPC1555C

TIMER CIRCUIT

NEC => Renesas Technology 

µPC1555

APPLICATION CIRCUITS

(1) Monostable multivibrator

Fig. a Monostable Multivibrator Example

VCC = 5 to 15 V

Note 10

RL

4

TRIGGER

2

8

7

µPC1555 6

3

OUTPUT

5

1

R1

C1

Control voltage

0.01 µF

Fig. b Monostable Response Waveform

t = 0.1 ms/DIV

Trigger input voltage: 5 V/DIV

Output voltage: 5 V/DIV

"H"

"H"

"L"

"L"

Capacitor (C1) voltage: 2 V/DIV

When the µPC1555 is configured as shown in

Fig. a, it functions as a monostable multivibrator.

Applying a voltage one-third as high as VCC or less

(trigger pulseNote 9) to pin 2 (trigger pin) drives the

output to a high level. Under this condition, capacitor

C1 starts charging through resistor R1. When C1 is

charged up to two-thirds as high as VCC, pin 6 (threshold

pin) is turned on and inverted to a low level. At this point,

C1 starts discharging through pin 7. When a trigger

pulse is applied to pin 2 again, the same operation is

repeated. Fig. b shows this operation. A capacitor

connected to pin 5 functions as a nose filter for the

control voltage. If pin 4 (reset pin) is connected to 1 V

or higher (for example, by being connected to VCC), the

circuit operation can be stopped by switching it from 2

V or higher to a GND level.

The output pulse width (delay) is determined theo-

retically by (see Fig. c):

t = 1.1 • C1 • R1

(R1 = 9.1 kΩ, C1 = 0.01 µF, RL = 1 kΩ)

Fig. c Interrelationships among Output

Pulse Width, R1, and C1 (approxi-

mate value obtained by calculation)

100

t = 1.1 C1 R1

10

(R1)

1.0

0.1

0.01

0.001

10 100 1.0 10 100 1.0 10

µs µs ms ms ms s s

Output pulse width t

The value obtained by this equation is only an approximate value, however. If it is necessary to obtain an accurate

output pulse width, determine R1 and C1 through actual measurement and confirmation; a trimmer should be used

as required. Moreover, R1 should be 300 Ω or higher.

Notes 9. Keep the trigger pulse width smaller than the output pulse width.

10. If the load is connected across the output and GND pins, a “staircase” occurs in the output waveform.

The application circuits and their parameters are for references only and are not intended for use in actual

design-in's.

7

Share Link: