SN65HVD75: Bus I/O shorted to GND

Hi Takahashi-san,

So the output current during a short circuit is limited to +/-160mA. So the device is protected against the current itself - but might not be directly protected from the self heating due to the current. 

However with that being said depending on operating temperature it could push the device into thermal shutdown. 

So if you are "D" package for example and you short driver output to GND if the bus output is trying to output a "high" value that means the power dissipated along the driver stack is VCC * I_OS - so 0.16 * 3.3 = 528mW. If you look at the R_theta_JA value for the "D" package it is 110.7C/W - so the temperature rise on the "D" package would be ~58C. If you are running the device at TA = 125C a short circuit to ground would most likely cause the device to violate the 150C junction temperature and go over the thermal shutdown limit (typically 170C) - which at that point the driver outputs will go hi-z. The important thing to note is that the thermal shutdown circuit typically kicks in 20C above the max junction temperature. 

Please note that this is just a rough example as the R_theta_JA value in the data sheet will be different for that part in customer system because that value is strongly influenced by specific system it is placed into - so the numbers will most likely be different for customer - however the concern is the same; shorts cause a lot of heat dissipation which may cause issues depending on operation point in which short occurs.  Adding things like heat sinks and if possible air flow over IC does improve that situation as it will lower the heat dissipation into junction. 

So the short circuit itself won't damage the device - but it will cause it to heat up quite of a bit which could lead to damage or pushing the device into thermal shutdown. 

Please let me know if you have any other questions!

Best,

Parker Dodson