HCF4047B

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Where tM = monostable mode pulse width. Values

for tM are as follows :

variation will be (+ 9.3%, - 0.0%).

Note : In the astable mode, the first positive half

In addition to variations from unit to unit, the

monostable pulse width may vary as a function of

4 - RETRIGGER MODE

The HCF4047B can be used in the retrigger mode

to extend the output-pulse duration, or to compare

the frequency of an input signal with that of the

internal oscillator. In the retrigger mode the input

pulse is applied to terminals 8 and 12, and the

output is taken from terminal 10 or 11. As shown in

fig.A normal monostable action is obtained when

one retrigger pulse is applied. Extended pulse

duration is obtained when more than one pulse is

second positive edge of the oscillator output

appears at flip-flop 4 (see logic diagram).

FIGURE A : Retrigger-mode waveforms

5 - EXTERNAL COUNTER OPTION

use of external counting circuitry. Advantages

include digitally controlled pulse duration, small

timing capacitors for long time periods, and

extremely fast recovery time.

A typical implementation is shown in fig. B. The

pulse duration at the output is

Where text = pulse duration of the circuitry, and N

is the number of counts used.

FIGURE B : Implementation of external counter option