Are you talking about the output:
1. from a real device or;
2. from a simulation of a 555 timer?
If (1) then please study the datasheet for the specific device that you are asking about.
If (2) the please specify which 555 spice symbol you are using by showing a screenshot of the library it came from.
If you are using the 555\_BJT\_EE spice symbol then please read the description and study the datasheet referred to in that description\.:
@andyfierman thank you for your reply\,i am talking about the output of 555\_BJT\_EE\, i am confused about its output voltage\,i will learn about the Device\,thanks\.
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