Patent ID: 7812576

Claim:
A boost converter, comprising: an inductance that receives an input signal; a switch that controls current supplied by said inductance to a load; and a power factor control module comprising: a mode control module that selects an operating mode of said boost converter, operating modes of said mode control module include a continuous mode, a discontinuous mode, and a critical mode, wherein said critical mode occurs when said current is equal to 0; and a switch control module that (i) switches said switch at a switching frequency, (ii) sets said switching frequency equal to a first frequency when said mode control module selects said continuous mode, and (iii) sets said switching frequency equal to a second frequency when said mode control module selects said discontinuous mode, wherein said first frequency is different from said second frequency, wherein said switch control module calculates an off-time period of said switch for said discontinuous mode, wherein said switch control module prevents said boost converter from operating in said critical mode by changing said switching frequency between said first frequency and said second frequency during said off-time period, and wherein said off-time period (i) begins at a peak of said current and (ii) ends when said current decreases to a zero-crossing point.