| ??? 08/31/05 13:49 Read: times |
#100350 - RS485 is a good alternative, indeed Responding to: ???'s previous message |
Erik said:
Thus I always (including this thread) push the use of RS422/RS485 transcievers for ANY signal that leaves the box. Yes, and there are very smart RS485 drivers like LT1785, providing 15kV ESD protection, protection against overvoltage up to +-60V, slew rate limiting to prevent impedance mismatch from eroding signal inegrity, a.s.o. Kai, your "terminations" is, in my opinion, just as risky if implemented with "the newbies flying leads" as is the ferrite solution. That's true. Anyhow, my point is that the resistors do not terminate to the line impedance, at the transmitter Zout is added and at the receiver Zin is added. Zin need not and must not be added with series termination! And to make the series termination impedance to equal the characteristic impedance of cable is really simple: Just add 47 Ohm, when driving a 100 Ohm cable with a 74HCMOS busdriver. For shorter cables even a certain impedance missmatch can be tolerated, especially if Schmitt triggers are used at the recieving end... Kai |
| Topic | Author | Date |
| driving ribboncabel - ESD precautions | 01/01/70 00:00 | |
| on interconnect | 01/01/70 00:00 | |
| Alternative | 01/01/70 00:00 | |
| comments. | 01/01/70 00:00 | |
| Recommended scheme | 01/01/70 00:00 | |
| 74H? | 01/01/70 00:00 | |
| nope | 01/01/70 00:00 | |
| Don't forget series termination | 01/01/70 00:00 | |
| series termination | 01/01/70 00:00 | |
| re: series termination | 01/01/70 00:00 | |
| an, in my opinion, much better way is to | 01/01/70 00:00 | |
| Series termination is the correct method | 01/01/70 00:00 | |
| both? | 01/01/70 00:00 | |
| Series termination prevents overshot | 01/01/70 00:00 | |
| HUH? | 01/01/70 00:00 | |
| Huh Huh? | 01/01/70 00:00 | |
| read the original post | 01/01/70 00:00 | |
| Think about the newbies | 01/01/70 00:00 | |
| That is exacltly why I always push the u | 01/01/70 00:00 | |
| RS485 is a good alternative, indeed | 01/01/70 00:00 | |
| Use a relay driver and sleep well ... | 01/01/70 00:00 | |
ferite bead, series termination, or | 01/01/70 00:00 |