Switch controller and converter including the same for prevention of damage

摘要

In a converter using a transformer, a switch controller controlling a main switch and an auxiliary switch increase a turn-on time of the auxiliary switch when a voltage of a signal corresponding to a current flowing to a primary coil of the transformer is greater than a reference voltage for a predetermined period.

主权项

1. In a device including a main switch and an auxiliary switch and controlling the main switch and the auxiliary switch in a converter for generating an output voltage by using a transformer, a switch controller comprising:
an oscillator for generating an oscillator signal; a duty controller for generating a duty signal for controlling switching operations of the main switch and the auxiliary switch by using the oscillator signal, a result of comparing a signal corresponding to a primary coil current flowing at a primary coil of the transformer and a predetermined reference voltage, and a result of comparing a feedback voltage corresponding to the output voltage and the signal corresponding to the primary coil current, the duty controller increasing a turn-on time of the auxiliary switch by determining to turn off the auxiliary switch after a maximum turn-on duration of the auxiliary switch has elapsed based on the result of comparing the signal corresponding to the primary coil current and the predetermined reference voltage; and a gate driver for generating first and second control signals for controlling switching operations of the main switch and the auxiliary switch by using the duty signal.