Patent ID: 9742291
Date: 2017-08-22
CPC Classifications: H02M

Claim:
1. A control circuit, comprising: a) a power supply circuit comprising a bias capacitor coupled between a power terminal and a common node, wherein said power supply circuit is configured to supply power to said control circuit via said bias capacitor; b) a detection circuit coupled between said common node and a current output terminal of a main power switch of a power stage circuit, wherein said detection circuit is configured to detect current flowing through said main power switch; c) a current feedback circuit configured to generate a feedback signal according to a difference value between a sense value obtained from a voltage at said power terminal during an off state of said main power switch and a present voltage at said power terminal, wherein said feedback signal represents an inductor current of said power stage circuit; d) a control signal generator configured to generate a control signal according to said feedback signal to control said main power switch; and e) said current feedback circuit comprising a trigger circuit configured to activate a trigger signal when said control signal represents an off state of said main power switch in each switching cycle, a sample and hold circuit configured to sample said voltage at said power terminal according to said trigger signal, and to generate said sense value, and a differential amplifier configured to generate said feedback signal according to said difference value between said sense value and said voltage at said power terminal.