Why need isolated IC in Aux car kit?

This kind of AUX car kit is supplied power by car and transfer audio signal to car by AUX cable. There is a ground loop. The positive electrons are transmitted from car to car kit by power cable, and some negative electrons will be transmitted from car kit to car by AUX cable. These negative electrons will cause current noise in your car speakers. We added one power isolated IC on PCB to prevent negative electrons escaping from Aux cable, so you can enjoy clean music on your car. You can see below picture. The isolated IC is bigger than Bluetooth module, and price is expensive. But the cancel noise effect is very good.

CRYSTAL CLEAR CALLS

Noise-cancelling technology ensures understandable calls without the annoying “speakerphone” sound. Your every word will come through clearly thanks to the HD Voice microphone. Whether you’re on a call or listening to music, the sound come out from car speakers.It's great enjoy.

VOICE GUIDANCE & CONTROL
Keep your hands on the wheel and simply use your voice to make and take calls.

MORE THAN JUST CALLS
When you’re not in a call, use it to stream music, GPS directions...

AUTO ON/OFF
When you get in your car, it automatically turns on using. Likewise, it will turn off by itself after you park and leave your car.