All:
Would appreciate some help on this. I am following the attached schematic which uses a 74xx245 (Octal 3 state non inverting). I can only assume the purpose of the 74xx245 is to act as a logic level translator to convert the incoming signals (pic micro)from 5v to 3.3 v for a LCD.
I have hooked up the schematic with VDD at 3.3v. When testing the A side on my scope I am seeing voltages of 5v which is correct as this is the pic outputs, but the B side is returning 4.3 volts to the LCD. Should the B side not return signals of 3.3volts, otherwise what is the point. Perhaps I am missing something in the schematic and/or it is not working properly?. I assume the 4.3v is simply the voltage drop from the internal circuitry of the xx245.
Seems to me the 74xx245 is the wrong choice of a translator and something else would be better suited, but I see it used in this particular arrangment before.
Comments/suggestions
Cheers
Would appreciate some help on this. I am following the attached schematic which uses a 74xx245 (Octal 3 state non inverting). I can only assume the purpose of the 74xx245 is to act as a logic level translator to convert the incoming signals (pic micro)from 5v to 3.3 v for a LCD.
I have hooked up the schematic with VDD at 3.3v. When testing the A side on my scope I am seeing voltages of 5v which is correct as this is the pic outputs, but the B side is returning 4.3 volts to the LCD. Should the B side not return signals of 3.3volts, otherwise what is the point. Perhaps I am missing something in the schematic and/or it is not working properly?. I assume the 4.3v is simply the voltage drop from the internal circuitry of the xx245.
Seems to me the 74xx245 is the wrong choice of a translator and something else would be better suited, but I see it used in this particular arrangment before.
Comments/suggestions
Cheers