RS485/RS232 Multiprotocol Transceiver IC
RS485/RS232 Multiprotocol Transceiver IC
(OP)
Hello,
I am using this LTC1387 software selectable multiprotocol chip with an RS485 to Ethernet converter. I am worried about the receiver inputs only being +/-25VDC. I have seen many RS485 transceiver chips with +/-60VDC on the front end of the receivers. IS there anything I can do to protect my receivers if say a voltage of 60V is produced? Resistor in series on the receiver line. A 80V rated schottky diode in parallel would not work because it will still blow the socks off the receiver.
Thanks
I am using this LTC1387 software selectable multiprotocol chip with an RS485 to Ethernet converter. I am worried about the receiver inputs only being +/-25VDC. I have seen many RS485 transceiver chips with +/-60VDC on the front end of the receivers. IS there anything I can do to protect my receivers if say a voltage of 60V is produced? Resistor in series on the receiver line. A 80V rated schottky diode in parallel would not work because it will still blow the socks off the receiver.
Thanks





RE: RS485/RS232 Multiprotocol Transceiver IC
If you are concerned about a specific threat by a known or expected device then we can address that. If you are just shotgunning don't waste your money here, it will work fine.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: RS485/RS232 Multiprotocol Transceiver IC
RE: RS485/RS232 Multiprotocol Transceiver IC
I think of using them but always end up having connector problems, etc., then having it just not make sense at some point.
Well heck, why do you want 60v?? Both these techniques are supposed to occur below +/- 15V!!
If you want to heap on more protection(I would not) then get out your 21V Transorbs and run them to the ground point, both low and high sides.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: RS485/RS232 Multiprotocol Transceiver IC
RE: RS485/RS232 Multiprotocol Transceiver IC
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: RS485/RS232 Multiprotocol Transceiver IC
RE: RS485/RS232 Multiprotocol Transceiver IC
Then again, since it may take a long time to deploy and retrieve a ROV, the operators may end up operating in a storm. Even though salt water is conductive, a long cable connected at each end to exposed metal may be a great lighting conductor!
RE: RS485/RS232 Multiprotocol Transceiver IC
One approach was to transformer couple all RS485 lines, similar to the approach Ethernet takes. This provide galvonic isolation to thousands of volts. Only downside is that you need to have constant transitions in your data, so the data needs to be NRZ encoded or similar. For this reason I opted not to go this way.
The other approach is simply use a fuse. Each line Tx+, Tx-, Rx+, Rx- gets a fuse. A small 0.1A fast blow fuse in series with each line has no effect on the data, adds no significant resistance, and will add enough protection to prevent the circuit from a major fault or huge differential voltages. There are also self healing fuses, but not sure how fast they are.
-Bill
CE Designer Forum
www.cedesigner.com