DRV8801 nFault output

I would like to use the nFault open drain output to turn on the LED in an Opto coupler to signal to our main controller. All our Opto LEDs are usually connected to 12V with a 680 Ohm current limit resistor. Is it safe to have the nFault pin connected to 12V through an LED and 680 Ohm resistor? The data sheet talks about a max "logic level" voltage of 7V. Also I cannot find any specification of how much current can be sunk by the nFault pin. Another question is about the 500mV max sense voltage. I am using a 0.25 Ohm resistor to limit the current to 2A. What will a short on the motor leads cause to the Sense input? During a motor short I can measure about 5A of current. This causes about 1.25V on the Sense input, way to much per data sheet.