| ??? 05/24/08 13:08 Read: times |
#155077 - RS485 experiences Responding to: ???'s previous message |
Stefan, ifyou want isolated RS485, you're going to have to have an isolated dc/dc converter for the 75176 as the others have mentioned. Things you need to watch when running DC down the same cable is voltage drop across the 0V signal - however having isolated 75176 means this is less of a problem. 75176's don't like having DC in excess of the spec applied to the AB pins,therefore I usually would use a couple of SA5.0 transzorbs and 100mA polyswitches in series to protect the device. Maxim, LT and others have product that eliminates this problem (LT1785 is one chip). Also you might find you'll need a common signal for the RS485 bus apart from the AB signals to get the common mode voltage amongst the node the same. |
| Topic | Author | Date |
| RS485 questions | 01/01/70 00:00 | |
| Yes its required | 01/01/70 00:00 | |
| + | 01/01/70 00:00 | |
| you can not achieve isolation .... | 01/01/70 00:00 | |
| + | 01/01/70 00:00 | |
| why common power and isolated 485? | 01/01/70 00:00 | |
| where to get supply | 01/01/70 00:00 | |
| RS485 experiences | 01/01/70 00:00 | |
| all the stuff inside | 01/01/70 00:00 | |
| Prifibus alike | 01/01/70 00:00 | |
| not with '176 | 01/01/70 00:00 | |
| sn75lbc176 planed | 01/01/70 00:00 | |
| why galvanic isolation ? | 01/01/70 00:00 | |
| what is wrong? | 01/01/70 00:00 | |
| then try MAX3158 | 01/01/70 00:00 | |
| how about this little gem? | 01/01/70 00:00 | |
| have you read it fully | 01/01/70 00:00 | |
| It's just another way to get the job done. | 01/01/70 00:00 | |
| OK, I'll bend it in neon | 01/01/70 00:00 | |
| Prifibus alike ..... it isn't | 01/01/70 00:00 | |
| Galavanic isolation | 01/01/70 00:00 | |
| Galavanic isolation | 01/01/70 00:00 | |
| Do it like Profibus | 01/01/70 00:00 | |
| economical approach | 01/01/70 00:00 | |
Thanks for all answers! | 01/01/70 00:00 |