Proposed C2 version

[Gondolindrim]

This C2 version improves upon C1 in shielding and grounding matters. It also adds additional shielding features that are optional and can be ignored. The C2 version has the same dimensions and screw hole sizes, making it fully backwards compatible with designs that were designed for C1.

• A ground copper pour was added to the front copper layer to lessen ground impedance. A ground copper zone was not added to the back copper to avoid short circuits between ground and metal case.

• The connector shelding was removed from a straight grounding and an ESD circuit, comprised of C1 and R3, offers a simple but efficient grounding from EMI from the cable/connector shield. The copper zone under the connector was removed to prevent unwanted short circuits between the PCB copper and the cable metallic enclosure. If the user wishes not to use this feature, lest short either the C1 or R3 pads and not add the components;

• An ESD net of D1, R4 and C2, was added to effectively filter ESD coming from the metallic case upon which the daughterboard will be screwed. To this effect, the straight grounding of the case through MH1 through MH4 was also removed to prevent electricity from the case to reach the PCB and also any voltage fault on the PCB to reach the case and affect the user. If the user does not wish to use this feature, simply not add the components. Shorting the pads of one of the components D1, R4 or C2 will hard ground the enclosure.

• To this effect, only mounting hole MH1 was connected to a current path. This prevents grounding loop currents between the mounting holes, by offering a single current path through which a possible discharge is dealt with.

[Gondolindrim]

This PR is being closed because a more modern and mature C3 version will be pull-requested in the near future.