Looking for RS-485 interface through a controller

Hello,

First of all, for new designs you might consider a newer transceiver like THVD1451 or THVD1452.  These have some improvements and optimizations over the previous-generation devices.

As to how to handle enable controls, that depends on the application.  If the node will always be the only node transmitting on a given bus (e.g., in the case of a "master" node) and if the receiver will always be active then you could use a transceiver with no enable controls.  If the application needs to be able to disable the driver circuit to allow for other nodes to communicate on the bus, though, then enable controls are required.

Regarding termination, the short answer is that it is generally beneficial to use termination resistances at the two furthest ends of the cabling and to have their values match the characteristic impedance of the cabling (which is typically 120 Ohms differential in RS-485 implementations).  For more detailed information, though, you can reference this blog:

https://e2e.ti.com/blogs_/b/analogwire/archive/2016/07/28/rs-485-basics-when-termination-is-necessary-and-how-to-do-it-properly

If you have any further questions on this topic, though, please just let us know.

Best regards,
Max

Yes, transceivers with integrated isolation are available as well.  I'd recommend considering ISO1452.  Or, if you prefer you could use a non-isolated transceiver like THVD1452 along with external isolation (for example, via a digital isolator circuit).  The reference design you mentioned shows such an approach which makes use of a digital isolator with integrated isolated power rail generation.

The level shifter is used in that reference design to allow the microcontroller to run at 3.3 V while the isolator  runs at 5 V.  This is not needed if the two interfacing devices share a common VCC supply or otherwise have compatible interface logic levels.

Max

Yes, that's right.  One solution would be to use a digital isolator with integrated power and an external 485 transceiver (which could give some flexibility in the transceiver selection) and another could be to use an isolated 485 transceiver with external power generation.  You might also consider something like ISO3086T which integrates a transformer driver that can be used in isolated power rail generation.

Max