The TOPSwitch family implements, with only three terminals, all functions necessary for a DC to DC, converter: high voltage N-channel power MOSFET with controlled turn-on gate driver, voltage mode PWM controller with integrated 120 kHz oscillator, high voltage start-up bias circuit, bandgap derived reference, bias shunt regulator/error amplifier for loop compensation and fault protection circuitry. Compared to discrete MOSFET and controller or self oscillating (RCC) switching converter solutions, a TOPSwitch integrated circuit can reduce total cost, component count, size, weight and at the same time increase efficiency and system reliability. This device is well suited for Telecom, Cablecom and other DC to DC converter applications up to