EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: bhj99 on May 05, 2023, 02:31:50 pm
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Hi all, I am am looking at a reference design involving a USB 2.0 DPDT switch NLAS7222A and was curious on the choice of resistor values R54 and R55 for the select input S on pin 10. The USB_EXT_VBUS would be 5V nominal. So, the voltage at pin 10 would be 5*(1/1.75) = 2.86V. From my understanding, wouldn't any V_IH of > 1.3V make the select input go high and just choose the resistors for the divider to meet that requirement? Or is there something in particular that I'm missing.
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The part isn't 5v tolerant on logic inputs so they are making a voltage that is comfortably under 3.3v even at worst case USB voltage high. I think they're just trying to make this clear.