Patent ID: 6084451
Filing Date: 2000-07-04
Classification: H03K

Abstract:
A pulse width modulation controller for controlling a power switch, controller comprising:an error amplifier for receiving an feedback voltage and a first reference voltage in order to generate an error voltage;a multiplying portion for receiving an externally applied voltage and the error voltage and outputting a first control voltage, where the externally applied voltage is a voltage generated by the power switch when the controller is configured to operate in a current mode, such that the first control voltage is proportional to the multiplication product of the voltage generated from the power switch times a second reference voltage less the error voltage, and where the externally applied voltage is a ground voltage when the controller is configured to operate in a voltage mode, such that the first control voltage is proportional to the multiplication product of the ground voltage and the second reference voltage less the error voltage;an oscillator for generating a clock signal and an inverse sawtooth signal;a first comparator for comparing the inverse sawtooth signal with the first control voltage in order to generate a second control voltage;a flip-flop having set, reset and inverting output terminals, the set terminal being configured to receive the clock signal, the reset terminal being configured to receive the second control voltage; anda logic gate having first and second input terminals and an output terminal, the first input terminal being configured to receive the clock signal, the second terminal being coupled to the inverting output terminal of the flip-flop, and the output terminal being coupled to the power switch such that the output terminal of the logic gate controls the power switch.