THVD8000: Short circuit protection for THVD8000

Hi Sajul,

The THVD8000 can handle shorts in the following conditions:

A to B short.

A or B to GND short.

A or B to -7V to 12V (DC) short 

And it will be limited to +/-250mA  as dictated by RS-485 standard which this device mostly follows (differential input thresholds being the largest difference) and if the device is in receive mode it will read a short circuit between A and B as a logic 1. 

If you are talking about a short to higher voltage source - which may be possible in THVD8000 applications - the protection is really going to vary based on how much power is expected. It could be something more simple like a TVS / Surge Diodes from A and B to GND, a TVS/Surge diode between A and B, and pulse proof resistors at the A and B pins directly (usually 10 Ohms- but pulse proof is important).  What parts you use - depends fully on the kind of surge you are expecting. 

Other current protection that is uncommon is just fuses to break the line during fault. 

Please let me know if you have an expected fault case outside of what I described above and I will see if we suggest anything different. In general when you are just using the THVD8000 alone - the above architecture should be sufficient - as in Higher voltage applications (generally those over 36V - 50V - think 120V and higher) we change our suggested architecture - but in standard use cases - the three protection diodes (A to GND, B to GND, A to B - make sure they are bi-directional) + pulse proof resistors + the coupling network should be okay. 

Best,

Parker Dodson