I have the following circuit, where I put R52 = R53 = 2700 Ohms :

Schematic http://free0.hiboox.com/images/5013/ac1bae22d71c2e3cc17b4ed3eda3090a.png

Triggering levels are of 1V and 2V approximately according to my computations, that is okay according to the following figure showing input in green and output in blue :

Output http://free0.hiboox.com/images/5013/92bf3b53a5576a7863be561d561b74fe.png

But what I find really strange is that the maximum voltage output is around 3.3V and not at 5V. How would you explain that ? And last detail : how would you explain that the output is not exactly at 0V when the input is high?

Thank you very much for your help.