CD14538B: Consultation on the output signal situation when the input signal of CD14538 changes

liujun

Part Number: CD14538B

Tool/software:

T=R1*C1

What is the high-level time of the Q pin output signal in Figure 1?

What is the formula for calculating the high level time of output signal Q when the period of the input signal is greater than T（T=R1*C1 ）?

When the period of the input signal is less than T, does the output signal Q always maintain a high level?

Figure 1

Thanks

3 months ago

0 Clemens Ladisch 3 months ago

Guru 316920 points

A trigger happens only on the falling edge of the SINGAL signal.

This device is retriggerable, i.e., each falling edge will extend the output pulse one period; see the bottom of p. 2 of the datasheet.

0 liujun 3 months ago in reply to Clemens Ladisch

Intellectual 310 points

Is the calculation result of T in Figure 1 the time width of the high-level output pulse at the Q terminal?

T=R1*C1=0.47s.

thank you!

0 Albert Xu1 3 months ago in reply to liujun

TI__Mastermind 38085 points

Hi Liujun,

Yes, that should be the general calculation. However, there is also a "K" factor involved (usually close to 1) but the datasheet provides some graphs for variation.

0 liujun 3 months ago in reply to Albert Xu1

Intellectual 310 points

thank you!

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CD14538B: Consultation on the output signal situation when the input signal of CD14538 changes