A burn-in system includes a testing stage configured to stress test one an integrated circuit and a power stage having a voltage control mode and a current control mode. The power stage is configured to supply power to the testing stage. One embodiment of the power stage includes a pulse width modulator, a current control circuit and a voltage control circuit. The pulse width modulator is configured to generate a modulated power output that is coupled to the testing stage. The current control circuit is configured to produce a current error output signal that is based on a difference between a measured load current, which is indicative of the current that is supplied to the testing stage by the modulated power output, and target load current. The voltage control circuit is configured to produce a voltage error output signal that is based on a difference between a measured load voltage, which is indicative of the voltage across a load of the testing stage, and a target load voltage when the power stage is in the voltage control mode. The voltage control circuit is further configured to produce the voltage error output signal that is based on the current error output signal when the power stage is in the current control mode. The modulated power output is based on the voltage error output signal.