Timeline for Proper shielding of a specific circuit
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Aug 1, 2023 at 12:01 | vote | accept | HansPeterLoft | ||
| Jul 31, 2023 at 8:56 | history | edited | Vincent | CC BY-SA 4.0 | added 31 characters in body |
| Jul 31, 2023 at 8:55 | comment | added | Tim Williams | Put another way: the chassis can be used as an extension of the ground plane. The minor tweak I would make here is to show the PCB-chassis GND connections clustered around the connectors, for this purpose. How close the signal shields must be to the PCB (or indeed right up to it) is determined by permissible crosstalk and data rate / bandwidth; you wouldn't strip shield from a USB-HS or eSATA port, but it won't matter for say RS-232. Overall great answer. | |
| Jul 31, 2023 at 8:34 | comment | added | Vincent | Inside the enclosure, a common solution is place cables against chassis for minimize the couplings (inductive because the loop surface signal/chassis (or ground) is minimum and capacitive with the multipoint grounding) with the internal noise sources. For your last question, in Europe the regulations require PE AND ground connected tightly together for safety reasons, except when no earth is present (aerospace or airborn application for example). | |
| Jul 31, 2023 at 8:34 | comment | added | Vincent | In general, it is important to have different strategies for internal EMC and external EMC (IEC 61000). The IEC 61000 standard lead to very strong disturbances from outside, EN 61000-4-4 (EFT) simulates motor starting, EN 61000-4-5 an indirect lightning strike, EN 61000-4-2 electrostatic discharge 4 or 8kV, etc. If you guide the shield on the inside to the PCB input connector and connect it there also to GND but EMC disturbances will be closer to your PCB. I strongly advise you to leave these problems outside the enclosure. | |
| Jul 31, 2023 at 8:33 | history | edited | Vincent | CC BY-SA 4.0 | added 2 characters in body |
| Jul 31, 2023 at 6:50 | comment | added | HansPeterLoft | Thank you, great illustrations. One problem i see with connecting the shield like in your last illustration is, that the signals are not shielded on the inside of the enclosure and when the noise source is there, it will directly couple into the senstive signals. Would it not make sense to further guide the shield on the inside to the PCB input connector and connect it there also to GND? You talk about grounding the shield, in your illustration this means PE AND ground connected tightly together? | |
| Jul 30, 2023 at 16:18 | history | answered | Vincent | CC BY-SA 4.0 |