Levii is a small and easy-to-use 
level shifter for the I2C bus featuring bus transfers with up to 800 kbit/s. This is indispensable in applications where two I2C buses have to communicate with different bus voltage levels.
Additionally, Levii offers two bi-directional pins for general purposes including a second I2C bus.
In case you want the buses to be galvanically separated, please have a look at our product Optii.
The application of Levii is quite simple and straight forward:
Just apply the I2C lines SDA, SCL, ground and the I2C supply voltage of both buses to Levii.
The VCC lines are requested to offer a voltage between 1,8 V and 5,5 V as a reference voltage on both interfaces of Levii. If one is without power, Levii stays inactive and no signal is transmitted to the other bus.
An application example is available on Levii's Example Transfers page.
Figure 1 shows a simplified schematic of Levii. All four lines are built the same way, they are internally pulled up by a 10 kOhm resistor (Rp) and protected by a serial resistor of 22 Ohm (Rs).