Patent ID: 7279869
Filing Date: 2007-10-09
Classification: H02M,H03F,H03K

Abstract:
1. A pulse frequency modulation control circuit for controlling a switching regulator having a switching circuit and an inductive device to convert an input voltage to an output voltage, the pulse frequency modulation control circuit comprising: a current sensing circuit for generating a current detection signal representative of a current flowing through the inductive device; a voltage sensing circuit for generating a voltage detection signal representative of the output voltage; and a pulse generating circuit for generating a pulse control signal in response to the current detection signal and the voltage detection signal, the pulse control signal having a plurality of switch cycles, each of which consists of an ON-time applied to turn on the switching circuit and an OFF-time applied to turn off the switching circuit, wherein: the ON-time is adjusted in accordance with the current detection signal such that the ON-time is prolonged in response to an increase of a maximum of the current detection signal, and the OFF-time is adjusted in accordance with the voltage detection signal such that the OFF-time is prolonged in response to a reduction of a falling rate of the voltage detection signal wherein: the pulse generating circuit comprises: a reference ON-time setting circuit for preventing the ON-time from being shorter than a predetermined reference ON-time, and an ON-time adjusting circuit for dynamically adjusting the ON-time in accordance with the current detection signal, wherein: the reference ON-time setting circuit comprises: