Patent ID: 8378957

Claim:
A detector circuit comprising: a first input configured to couple to a set point terminal of a constant current source, the constant current source comprising: a transistor comprising a gate, a source, and a drain; and an operational amplifier comprising an inverting input, a non-inverting input, and an output; wherein the gate is coupled to the output of the operational amplifier, the source is coupled to a drive voltage node, the drain is coupled to a load, and the non-inverting input is coupled to the set point terminal; a second input configured to couple to the inverting input of the operational amplifier and the source of the transistor of the constant current source; and an output for setting a flag indicating that the transistor is operating in the triode region; wherein the detector circuit is configured to compare a difference between the voltage at the first input and the voltage at the second input to a reference condition, the reference condition being based on the triode transition voltage of the transistor at a selected drain-source current, and set the flag at the output when the difference exceeds the reference condition.