I'm using the ADG3304 to translate the level of four input signals from 5V to 3.3V, but I have some problems.
The configuration is as follows:
I interface the input signals with HCPL-063A optocouplers. The output signals from this optocouplers have 1K pull-up resistors to 5V.
Then the signals are connectet to the Y pins of ADG3304 (the Vccy and EN are connected to 5V, while the Vcca is at 3.3V; also I have 100nF capacitor between Vccy and ground). Then the outputs of ADG3304 are connected to GPIOs of a BF518 dsp. (see attached image)
Between the HCPL-063A and the ADG3304 I had 1K resistors, but the signals that arrived at the DSP was always neither high nor low (a broad signal about 1.5V).
Now I removed those resistors but the signals at the DSP are always like this.
I'm not skilled in electronics, I hope someone can help me to better understand how to correctly configure this connection.