Patent ID: 9627983
Date: 2017-04-18
CPC Classifications: H02M

Claim:
1. A control circuit for suppressing excessive current in a voltage converter having a main switch controlling a primary current passing through a primary winding of a transformer, comprising: an acquisition unit for measuring a first voltage applied on a sense resistor connected in series with the primary winding at a moment an active state of a leading-edge blanking (LEB) signal for shielding an initial spike of the primary current ends, wherein the acquisition unit comprises a comparator having a non-inverting input end connected to the first voltage and an inverting input end connected to a reference voltage; and an oscillator connected to the output of the comparator, wherein a comparison result from the comparator is transmitted to and the comparison result triggers the oscillator to transmit a clock signal at a reduced frequency for preventing the primary current flowing through the primary winding of the transformer from exceeding a pre-set value when the first voltage exceeds the reference voltage.