8 Channels di-directionnal level shifter
The purpose of this converter is to allow the technologies 3.3V and 5V to coexist on the same mount. Indeed, the Arduino and Basic Stamp platforms work in 5V logic whereas most advanced sensors and extensions (LCD screen, Flash card,..) only work in 3.3V.
As assembly designers, you will need components to convert the voltage between 5V and 3.3V... protecting your 3.3V circuits from the 5V power supply.
It is possible to use voltage divider bridges made with resistors but these resistor mounts can slow down your circuits and cause problems/malfunctions really difficult to debug.
For this reason, Adafruit first used logic circuits of the 4050/74LVX245 series to perform logic transfer between 5V and 3.3V voltages. However, this series only works in one direction, which can present a problem in the implementation of BiDirectional interface... and make the mount implementation a little more complex.
This is where the bi-directional converter, the beloved TXB0108, comes in, component making this breakout truly unique!
This component performs a level shifting voltage conversion in both directions from almost any voltage to any voltage and will auto-detect direction. The only domain for which it does not work very well is the I2C bus (because it uses powerful pull-ups that disrupts the auto-detection direction sensor).
If you need to use pull-ups, this is possible but you have to use at least 50K Ohms resistors - The Arduino/AVRs internal pull-up resistors are about 100K Ohms, so perfect!
Using TXB0108 is more expensive than a 74LVX245 but you do not have to worry about the direction of the signal, which really makes life easier!
This breakout will save you from having to weld very small components. Adafruit also add 0.1µF capacitors on both sides of the converter and a pull-up resistor of 10Kb on the "output enable" pin... so you can use this circuit directly!