Patent ID: 7034586

Claim:
A startup circuit for a DC—DC power converter, the power converter including an error amplifier which provides a compensation signal to a pulse width modulation (PWM) circuit that uses the compensation signal and a triangular PWM waveform to develop a PWM signal to control a switching circuit which converts an input voltage to an output voltage relative to a common power reference voltage, the switching circuit including an enable input, said startup circuit comprising: a first circuit that establishes a minimum peak voltage and a maximum peak voltage for the triangular PWM waveform; a second circuit that establishes a reference voltage having a linear relationship with the output voltage, wherein said reference voltage ranges from said minimum to maximum peak voltages while the output voltage ranges from the common power reference voltage to the level of the input voltage; and a comparator having a first input for receiving the compensation signal, a second input receiving said reference voltage, and an output providing an enable signal which is for providing to the enable input of the switching circuit.