Q
I do not fully understand the "dc correctness and magnetic field immunity"
paragraph in the data sheet. The AC part is clear. But should I understand the
DC part as: If the input signal is between low threshold (0.8 V) and high
threshold (2.0 V) for more than 5 microsecond, the output will be defined by
the truth table. But what does the table say about undefined logical inputs?
Can you describe this a little better?
A
The DC correctness section says if the input does not detect a transition for
about 1us, then the encoder will send a refresh pulse indicating the state of
the input as high or low. If the level is not defined, as it would be for
between 0.8V and 2V, there is no guarantee what level of refresh pulse will be
sent, but what ever side of the threshold the input is, it will send that
refresh pulse. If you have noise on the input and the input is near the
threshold, keep in mind that there is about 100mV hysteresis and if the noise
is larger than this, the output could follow the noise and chatter.