Patent ID: 7944191
Filing Date: 2011-05-17
Classification: H02M,Y02B

Abstract:
1. A switch mode power supply (SMPS) capable of operating in three different operational modes including a buck mode, a boost mode, and a buck-boost mode, comprising: a power stage further including a plurality of switches operatively switched to generate an output signal that has a predetermined relationship with an input signal, depending on which operational mode has been selected; and a controller stage for determining said operational modes, each of said operational modes being set by determining logic values of a first control signal at a first clock signal of fixed frequency and a second control signal at a second clock signal of fixed frequency respectively, said controller stage operable to change said logic values of said first control signal and said second control signal by comparing feedback signal (FB) to a reference signal (V wherein said clock-and-ramp generator further comprises: a current source operable to generate a fixed current; a first NAND gate electrically coupled to receive said first clock signal to drive a first n-channel Metal Oxide Semiconductor transistor; a second NAND gate electrically coupled to receive said second clock signal to drive a second n-channel Metal Oxide Semiconductor transistor; an offset voltage source, electrically coupled to said second nMOS transistor operable to generate a DC offset voltage proportional to said fixed frequency and said phase difference between said first clock signal and said second clock signal; and a capacitor electrically coupled to said current source, said first nMOS transistor and said second nMOS transistor.