MAX3222: output has a step

Hi ACGUY,

I have a guess as to what may cause a waveform like this... 1) The PFET driving HIGH is partially turned on while the NFET driving low is transitioning on resulting in some contention between the two for a small amount of time resulting in this step you're seeing. 2) There is some kind of pass FET architecture on the output (like a level shifter or MUX) resulting in the two sides of the level shifter/MUX waiting for the capacitive loading to equalize. I assume #2 isn't the case since it's rare for RS232 output signals to be MUX'd/shifted..... 

I've assigned this thread to one of our RS232 experts to comment on but in the mean time, could you please provide answers to the following:

A) Is this waveform you're seeing occurring in multiple devices (10 out of 10 or only 1 out of 10 for example?)

B) Do you have a schematic we can review? 

-Bobby

ACGUY,

Thanks for your information. The reason of the step is like #1 point Bobby mentioned. Given the voltage level and slew rate are complied with the RS-232 standard, this behavior should not impact system performance and it raises no reliability concerns either. 

Regards,