The C3 version is a more complete version of C2. It integrates:
ESD protection on USB data lines with U1, a specific ESD chip for USB type C; this chip is parallelized to the lines so it is optional in the sense that the data lines will be there even if the chip is removed;
Overcurrent protection through a resettable PTC fuse F1;
Transient Voltage Supression of the USB power rails through a TVS diode D1;
The grounding is done through a star grounding configuration. On both top and bottom sides of the PCB there is a copper pour that corresponds to the power ground to which the USB ground signal, the connector shielding are connected. The GND signal that goes to the main PCB is isolated from noise and sudden currents through a ferrite bead L1, a low-resistance bead with 120 ohms impedance at 100MHz;
All mounting screws are isolated except for one. This particular mounting screw is tied to the power ground signal, yielding a double shielding effect. This screw grounds the case and ensures any possible discharge from the ambient or the user is fed back to the USB shield through a single possible path, avoiding current loops inside the case material. Since this screw is electrically active, it is highly advised to use stainless steel screws to avoid oxidation;
The other three screw points are metallized only on the top part; this avoids any possible short-circuit with the case.
However, C3 also aims to be backwards compatible with C1:
C3 has the same dimensions and screw points than C1;
C3 uses the same connector footprint for the USBC and the same JST connector than C1
Adittionally, C3 is compatible with the JLC SMD Assembly library so that it can be order already assebled at very low cost.
Aesthetically, C3 features a logo of nine stars, each representing the designers involved in its creation.
The C3 version is a more complete version of C2. It integrates:
However, C3 also aims to be backwards compatible with C1:
Adittionally, C3 is compatible with the JLC SMD Assembly library so that it can be order already assebled at very low cost.
Aesthetically, C3 features a logo of nine stars, each representing the designers involved in its creation.