HEF4001UB 데이터 시트보기 (PDF) - Philips Electronics

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HEF4001UB

Quadruple 2-input NOR gate

Philips Electronics 

Philips Semiconductors

Quadruple 2-input NOR gate

Product specification

HEF4001UB

gates

APPLICATION INFORMATION

Some examples of applications for the HEF4001UB are shown below. Because of the fact that this circuit is unbuffered,

it is suitable for use in (partly) analogue circuits.

INH

O

H

L

L

OSC

In Fig.9 the oscillation frequency is mainly determined by R1C1, provided

R1 << R2 and R2C2 << R1C1.

The function of R2 is to minimize the influence of the forward voltage

across the protection diodes on the frequency; C2 is a stray (parasitic)

capacitance. The period Tp is given by Tp = T1 + T2, in which

T1 = R1C1 ln -V----D---D-V----+S----T-V----S---T-- and T2 = R1C1 ln-2--V-V----D-D--D-D----–-–----VV----S-S--T-T--- where

VST is the signal threshold level of the gate. The period is fairly

independent of VDD, VST and temperature. The duty factor, however, is

influenced by VST.

Fig.9 (a) Astable relaxation oscillator using two HEF4001UB gates; the diodes may be BAW62;

C2 is a parasitic capacitance.

(b) Waveforms at the points marked A, B, C and D in the circuit diagram.

January 1995

6

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