Abstract: A control circuit for the regulation of fan speed control in a computer power supply with software controlled shutdown and automatic restart for over-temperature protection. The control circuit overrides the control inputs when the temperature inputs indicate a temperature above a specific level.

Abstract: A snubber circuit with two switches which are switched together. The two switches form a pair of active networks with complementary diode locations, and a capacitor is connected to provide a path for transient current through both diodes. The two switches are preferably switched simultaneously to minimize conduction losses. When Switches S1 and S2 are turned off, the voltage through across capacitor Cs is nearly zero. Turning off S1 and S2 causes current flowing through S1 and S2 to be diverted through D1, Cs, and D2. Therefore, the voltage across S1 and S2 is a very low value and consequently, the turn-off losses are low. Alternatively, at the time when S1 and S2 are turned on, the peak current through S1 and S2 is equal to the boost inductor current. Therefore switching losses are minimized and the converter can operate at higher frequencies.