Patent ID: 7102340
Filing Date: 2006-09-05
Classification: H02M,H05B

Abstract:
1. A dual-mode pulse frequency modulation boost converter comprising: a power conversion circuit that receives an input voltage at a first level and that generates an output voltage at a second level, wherein the power conversion circuit includes a switching transistor to generate the output voltage; a pulse frequency modulator configured to control the switching transistor; an inner control loop configured to sense a switching current flowing through the switching transistor and to generate a first feedback signal to the pulse frequency modulator to turn the switching transistor off for a predefined duration when the switching current reaches a predetermined level, wherein the predetermined level is substantially constant in a first mode and is controlled by an output voltage feedback signal in a second mode; and an outer control loop configured to sense a load current, wherein the output control loop turns the pulse frequency modulator off when the load current is greater than a reference level during the first mode and forces the pulse frequency modulator to stay on during the second mode.