I have a replacement of the internal USB camera for the laptop Acer Aspire 5750G. AFAIK USB has only 4 connections (5V, D+, D-, GND). On the PCB of the camera I noticed there are 5. They are labeled: 3.3V, D+, D-, GND and SH. Does anyone know what is "SH" connection for? It seems that it's just connected to GND but I'm not sure. Can anyone help me? Thank you.