Other Parts Discussed in Thread: SN65HVD234
Does the +-70V fault protection on the SN65HVD1781 also include protection against putting 70V directly across the A and B terminals? From what I can tell from the datasheet it looks like the fault protection is for voltages applied between one bus pin (A or B) and GND or VCC, but doesn't say anything about protection from voltages applied directly between pin A and B.
I have a unique possible application I'm investigating which involves sharing the bus wires between RS485, CAN, and " raw pulse" formats (not at the same time). A SN65HVD1781 (for RS485) and SN65HVD234 (for CAN) would share the two bus pins, but only one (or neither) device will be enabled depending on what type of bus the end user wants to use. Disabling either of those two devices would put its bus pin drivers into a high impedance state so it shouldn't affect the bus when disabled. The "raw pulse" format wouldn't use either of the two aforementioned devices, but instead would consist of a circuit to detect voltage pulses between about 7 and 26 volts between bus wires and is the reason why I'd like clarification of the specified fault protection. I see the SN65HVD234 has overvoltage protection up to +-36V, so I'd think 26V is OK. The bus could then be externally connected to other similar devices using either RS485 or CAN signaling, or alternatively could be controlled by a battery and mechanical, manually activated switch (think simple "external trigger"). The two devices need to then be capable of withstanding voltages up to about 26V between their two bus pins. I know I could mechanically switch the bus wires between devices (say with jumpers) depending on chosen bus type, but that would add complexity and it would be preferred if I could just connect all bus wire pairs together and expose a single two-pin connector to the end user.
Would this configuration be possible? Thanks!
