Patent ID: 7239495

Claim:
An output circuit comprising: an output transistor connected in series with a load, wherein the output transistor supplies a load current; and a protection circuit for protecting the output transistor, wherein the protection circuit comprises a current detection circuit which detects if the load current exceeds a threshold value, and an off-signal generation circuit for generating an off-signal to turn off the output transistor, wherein the off-signal generation circuit generates the off-signal after an elapsed time from the detection of the load current exceeding the threshold value and the elapsed time depends on a voltage drop of the output transistor, wherein the off-signal generation circuit comprises a clock signal generation circuit which generates a clock signal and a counter for counting the clock signal and generating the off-signal after counting a given number of clocks, and wherein the clock signal generation circuit comprises a current generator which generates a current depending on the voltage drop of the output transistor and a capacitor to be charged with the current generated by the current generator, and the clock signal has a cycle depending on a charge time of the capacitor.