Patent ID: 7605598

Claim:
A power semiconductor device, comprising: an output transistor having main cells and sense cells, a control input connected to the main and sense cells, and main and sense cell controlled outputs; an output terminal connected to one of the main cell controlled outputs for connection to a load; a feedback circuit for measuring the voltage across the main cell controlled outputs of the output transistor and for controlling the voltage on the control input, the feedback circuit including a first comparator configured to output a signal responsive to the magnitude of the voltage across the main cell controlled outputs and a diode connected in series between the output of the first comparator and the control input, the diode orientated to pass current between the output of the first comparator and the control input to increase the voltage across the main cell controlled outputs; a reference current supply feeding a reference current through the sense cell controlled outputs; and a second comparator arranged to compare the voltages across the main cell controlled outputs and the sense cell outputs and to output a low-current signal when the magnitude of the voltage across the main cell controlled outputs falls below that across the sense cell outputs.