SN65HVD3085E: What's the difference

Hi Yoshihiko,

The short answer is yes - you should be able to implement the THVD1520DR in place of the SN65HVD3085EDR without modification in most applications. The THVD1520DR has the same pinout and its main differences are that the THVD1520DR has a wider hysteresis curve which gives it more immunity to events that could cause glitches, the THVD1520 consumes slightly less power,  and the THVD1520 supports up to 10Mbps (but it support lower rates) 

The longer answer is yes - but since the THVD1520 can support higher data-rates as its transition edges are faster - this means that even when using it at a data-rate that can be handled by both of the devices mentioned above the 1520 will have more energy at higher bandwidths due to its faster edge transitions. If the system is terminated (120 ohms on each end of bus and a 120 characteristic impedance path/cable between the nodes) than these faster edge rates shouldn't be too much of a concern. If the system is unterminated then things like length of signal path, number of nodes, and data-rate need to be check to see if 1. What frequency bands of the data signal do I need to consider for transmission line effects and 2. are the reflections on the line large enough to corrupt data? 

So essentially if the system is terminated  (120 ohm resistors from A to B on the two RS-485 nodes on each end of the cable  (if more than two nodes only the extreme ends of the line need to be terminated) and the characteristic impedance of the transmission line is ~120 ohms then there shouldn't be much of an issue. However one more thing to note is if anything else is added to the A/B bus besides the termination resistors and transceivers as this could effect internal hysteresis  of the device and could change operation. But in general if they are both used in typical RS-485 terminated applications it should be okay to drop in replace the part.

If you have any other questions please let me know!

Best,

Parker Dodson