I am working on a project to output a graph from an Arduino Uno R3 to a generic TFT screen. The TFT screen needs a 3.3V input instead of the 5 V output by the Uno. I am trying to use an Adafruit 8-channel voltage leveller to make this transition. The voltage leveller uses the Texas Instruments TSX0108 chip. Here is a photo of the chip on my board. I have noted the voltages associated with each wire.
In the pictured set up, I am trying to make sure the voltage leveller is working because when I hooked it up to my screen, the Arduino could not run the display.
When I power up the voltage leveller using the Arduino 5V output connected to B1 using the arrangement in the photo (see schematic below), I measure output voltage on A1 of 0.000 V.
Everything I've read seemed to say the TSX0108 had internal pull up resistors. However, I decided to add a resistor (see schematic below for where I put the resistor). Once I added a resistor, I was now able to measure an output voltage on A1. However, the output voltage was not 3.3V as I expected it to be. The highest I've been able to get the voltage on A1 was 2.2V.
Should I just keep trying a larger resistor until A1 outputs 3.3V when B1 is 5V?
If I need a pull up resistor that seems to defeat the purpose of a voltage leveller. I might as well just make a voltage divider using resistors without the chip. Has anyone else encountered this with the Adafruit 8 channel voltage leveller?