THVD1450: Driver output short to GND?

Hi Lutz,

Lutz Naumann said:

What is not clear to me is what happens to the driver if one of the driver outputs shorts to GND permanently in case of cable failure or miswiring. Will the driver survive?

Yes, the device is expected to survive this since this technically is part of the IOS spec definition (if the output is shorted to any voltage between -7V to +12V which includes GND).

Typically what you see when a PFET is shorted is the FET enters saturation mode and the current gets restricted as VDS gets larger. Since the current technically gets limited, at some point the thermal build up will flatten (stop getting hotter). 

Lutz Naumann said:

I assume the power stage will operate at is short circuit current capability permanently.

Correct, if the power rail doesn't brown out then the device will continue to hold that short.

Lutz Naumann said:

Is there a thermal or other protection or is this potentially subject to fail? I is great that the receiver is fail safe.

No, our devices with thermal shutdown will be called out in the datasheet in the electrical parameters section. This device doesn't include a thermal shutdown circuit.

Lutz Naumann said:

But what about the output?

You mean the R pin? It will reflect whatever A-B logic is. So it depends which pin gets shorted to GND. If A gets shorted to GND you will probably have R stuck at a logic low. If B gets shorted to GND, you will probably see R hold a logic high. This is assuming the receiver circuit is enabled (RE# is held low).

-Bobby