I have 6 RGB LED strips and I would like to control them by Raspberry PI. 6 strips with 3 colors each require 18 controllable PWM sources, so I have SN3218 which is exactly what I need. But I am not sure how to connect it with the LEDs because they are 12V and I have 3 or 5V. I tried to use this tutorial https://popoklopsi.github.io/RaspberryPi-LedStrip but the problem is that from Raspberry itself there is positive output pin but SN3218 has negative outputs. My naive approach would be to change NPN transistor to PNP but I guess that it won't be so easy.
Here is a schematic from this web page which shows a TTL to 12 volt inverting switch.
If the SN3218 outputs are open collector you should add pull up resistors at the SN3218 output pins.