I am looking for an advice or brainstorm on what transceiver to use for fault tolerant RS485 in industrial environment.
Have 12V, A, B, GND bus on shielded 22/4, distance approx 20-30ft, baudrate 115.2k. Despite several protection mechanisms I seen MAX485 die or degrade, even though they should survive 12.5V and transceiver is shortable, and thermal protected. On at least two occasions I seen MAX485 inexplicably heat up - it was still communicating, but stopped when too hot and fully recovered after power down and cool-off and did not heat up anymore. Anyone seen MAX485 randomly inexplicably heat up ?
Looking to improve reliability by changing transceiver. The nodes must instantly recover from shorts to ground, bus 12V or between A and B without degradation.
Here is my current list of alternatives:
ST485 is rated up to ±14V on the bus lines. Gives more room than MAX485. Otherwise seems to have same protections.
SP485 (Exar/Sipex) is rated up to ±15V on bus lines, and Table 1 suggests chip disables outputs when fault is detected even though fault protection is not specified as feature.
75LBC184 is also rated to survive pernament ±15V on bus lines plus it has TVS built-in on both lines.