| Jan Waclawek 06/06/09 04:29 Read: 237 times Bratislava Slovakia |
#165895 - isolation Responding to: Farshad Mohajeri's previous message |
Farshad Mohajeri said:
1) The horizontal design where both USB and RS485 ports are side by side, should be replaced by a vertical design where ports are on the opposing edges
2) The isolation gap between two grounds is not big enough I don't think these are really issues. There is more capacitive coupling in the optos than between the planes you have, and you can't really widen the gap beyond the distance of optos' pin rows. Farshad Mohajeri said:
3) Whole device can be powered from USB port, eliminating the EMI from power lines. (The reason that I didn't design it this way from beginning is that I wanted to isolate the PC from the converter as much as I can) This is the first thing I would do. Farshad Mohajeri said:
4) Place a ferrit-bead to filter power at USB chip VCC pin(s) Certainly. And 5V transils between the signals and the USB GND. Farshad Mohajeri said:
5) Reduce the copper in USB port area to the least possible area. Maybe, but not primarily. Farshad Mohajeri said:
6) Place the USB chip inside a faraday cage?
I don't think so. JW |
| Topic | Author | Date |
| FT232R USB to Serial | Farshad Mohajeri | 06/04/09 12:30 |
| Something silly ? | Steve M. Taylor | 06/04/09 13:36 |
| Capacitive Coupling | Farshad Mohajeri | 06/04/09 15:13 |
| Ideas | Steve M. Taylor | 06/04/09 15:51 |
| there is always SOME coupling... | Jan Waclawek | 06/04/09 15:52 |
| crash and reset the USB connection | Andy Neil | 06/04/09 16:24 |
| Very unlikely | Farshad Mohajeri | 06/04/09 16:30 |
| PC USB crash | Oliver Sedlacek | 06/05/09 03:06 |
| Isolated hub? | Andy Neil | 06/05/09 03:18 |
| PC Isolation? | Andy Neil | 06/05/09 03:20 |
| just blame the chip. | Erik Malund | 06/04/09 20:29 |
| Please see my other post with image (nt) | Farshad Mohajeri | 06/05/09 13:25 |
| is connector grounded on Your side? | Stefan KAnev | 06/05/09 01:42 |
| Huh? | Joseph Hebert | 06/05/09 09:21 |
| yes | Stefan KAnev | 06/05/09 09:38 |
| Floating the end of the cable shielding | Joseph Hebert | 06/11/09 11:37 |
| Was using wrong cable | Farshad Mohajeri | 06/11/09 12:36 |
| More information | Farshad Mohajeri | 06/05/09 13:21 |
| Hmm | Steve M. Taylor | 06/05/09 16:18 |
| isolation | Jan Waclawek | 06/06/09 04:29 |
| Update... | Farshad Mohajeri | 06/11/09 03:40 |
| USB and RS485 | Joseph Hebert | 06/11/09 11:44 |
| could this be it | Erik Malund | 06/11/09 12:01 |
| Tested both self-powered and bus-powered | Farshad Mohajeri | 06/11/09 12:41 |
| RS485 Converter | Farshad Mohajeri | 06/11/09 12:11 |
| el.circui? | Stefan KAnev | 06/11/09 13:59 |
| re: why? | Andy Peters | 06/19/09 12:22 |
| USB 1.1 | Farshad Mohajeri | 06/19/09 15:20 |
| re: USB 1.1 | Andy Peters | 06/19/09 16:34 |
popular culture | Jan Waclawek | 06/19/09 17:10 |