| ??? 03/24/07 02:23 Read: times Msg Score: +1 +1 Good Answer/Helpful |
#135738 - Clock signals Responding to: ???'s previous message |
Hi Mike,
Just out of curiosity, how do I calculate the minimum track width required based on a given track length and the frequency that goes through it? See previous replies. As for your clock, I've never had a need to control the impedance of my clock traces on an 805x board. I will tell you this. Make the traces as short as you can. I'm assuming you're using FR4 material, which means that as long as your traces are less than 6 inches or so you shouldn't really see any high speed effects and you shouldn't need controlled impedance. I can tell you that I use an oscillator, not just a crystal and parasitic caps. As for trace widths, mine are generally 0.010" wide. You say yours are almost 0.012" wide (0.3mm), so I don't see that you should have any problems. You should understand though, that trace length, while important to high speed digital effects, is irrelevant to trace impedance. Also, I do mine on a 2-layer board as well, and I don't have any high speed problems. For Kai, et al, I will add that I don't worry about EMC. If I were worried about EMC I would definitely be building 4-layer boards with Vcc and GND planes. |
| Topic | Author | Date |
| Track lengths and widths (8051) | 01/01/70 00:00 | |
| Controlled impedance | 01/01/70 00:00 | |
| It wont work out | 01/01/70 00:00 | |
| See the edited version of my original reply. | 01/01/70 00:00 | |
| an approximation is OK. | 01/01/70 00:00 | |
| Hard to really guide but... | 01/01/70 00:00 | |
| thanks for the width | 01/01/70 00:00 | |
| This is why Erik goes ballistic | 01/01/70 00:00 | |
| Clock signals | 01/01/70 00:00 | |
| thank you | 01/01/70 00:00 | |
| fast signals don't care about width | 01/01/70 00:00 | |
| "Clock signals"? | 01/01/70 00:00 | |
| clock | 01/01/70 00:00 | |
| be careful, Mike | 01/01/70 00:00 | |
| 1983 Fourth Edition | 01/01/70 00:00 | |
| Length is more important than width | 01/01/70 00:00 | |
| Try this, Mike | 01/01/70 00:00 | |
| I've tried to explain this. | 01/01/70 00:00 | |
| What Mike wants | 01/01/70 00:00 | |
| I meant "Dave and Kai" | 01/01/70 00:00 | |
| I understand... | 01/01/70 00:00 | |
| Join the club! | 01/01/70 00:00 | |
| Interesting note, Kai... | 01/01/70 00:00 | |
| signal integrity | 01/01/70 00:00 | |
Very cute | 01/01/70 00:00 |