Hi,

I am designing a circuit in which cathode is connected to a CLOCK and anode is pulled up to 5V.
My intention is when The pullup is present the clock should come at the load.
When pullup is not present output should be zero.

But what I can see is when pull up is not present there is a spike in output waveform.

When Pull up is present.



When Pullup is not present

 

It's due to the internal capacitance of the diode.
The datasheet gives the capacitance as 5pF
Replace the diode by a 5pF capacitor and see if you get the same spike.

 

Thank you.
I understood the problem.
May I know how any method to avoid the spikes

 

Thank you.
I understood the problem.
May I know how any method to avoid the spikes

Any of the following. . . .
Ignore them. Will they actually cause a problem?
If your GPIO has a filter option, use it.
Put a bigger capacitor across the 1M resistor (i.e. bigger than the diode capacitance)
Use an AND gate (74LVC1G08) instead of the diode circuit.

 

Ignore the spikes, they are not a real-world concern.