AnsweredAssumed Answered

signal rise time dependent (?!) on vertical zoom

Question asked by aurgathor on Jul 21, 2012
Latest reply on Jul 24, 2012 by algoss
I have an MSO9104A scope (well, rented by my employer ) and a small portion of my work is to characterize some signals. When I measure the rise time of a roughly 410 kHz I2C signal with vertical scale set to 1V, it's about 185ns. If I zoom out to a scale of 3.3V, the rise time is about 160 ns. Zooming out further to 5V gets me ~147 ns. On the other hand, zooming in to 500 mV gets me about 190 ns.

WTH is happening here?!   Why am I getting different results?   The only thing I'm doing is just changing the vertical scale. 

Methinks scaling should have no effect on rise time, but the scope is apparently giving me different results. The signal is 3.3V, BTW.