Delayed Pulse Circuit

dl324

Joined Mar 30, 2015
17,152
I would like to know how to
determine the time delay.
The output of U4A will change when the input with the RC delay rises to the minimum value for a HIGH input. For CD4011 operating at 5V, that's typically 2.75V, but it could be as high as 3.5V.

Using the typical value:
\( \large V_f=V_i(1-e^{\frac{-t}{RC}})\)
\( \large t=-RCln(1-\frac{V_f}{V_i}) =-(10k\Omega)(10pF)ln(1-\frac{2.75V}{5V}) = 80ns\)
Or 0.8RC for typical and 1.2RC for maximum.
 
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Thread Starter

maker_2023

Joined Nov 20, 2023
173
The output of U4A will change when the input with the RC delay rises to the minimum value for a HIGH input. For CD4011 operating at 5V, that's typically 2.75V, but it could be as high as 3.5V.

Using the typical value:
\( \large V_f=V_i(1-e^{\frac{-t}{RC}})\)
\( \large t=-RCln(1-\frac{V_f}{V_i}) =-(10k\Omega)(10pF)ln(1-\frac{2.75V}{5V}) = 80ns\)
Or 0.8RC for typical and 1.2RC for maximum.
Thanks Dennis
 
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