I am trying to downshift a 5V TTL signal to 3V logic signal using NTB0102 level shifter. The connection is described below:
However, my oscilloscope measurements are distorted. Even the input signal (out of the microcontroller pin-pin connected) does not look like a true TTL 0-5V signal:
Placing caps on VCC does not help. Reversing the propagation way (0-3V input to 0-5V output) also produces ugly picture. Pulling UP/DOWN microcontrollre's output pin does not make a difference. Any ideas about what's going on?
The layout:
After someone suggested using 10x probes, I have an improvement in the output signal, but it still does not like a square wave:
Best Answer
Two more guesses: