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US 8,947,893 B2Granted
Switch controller and converter including the same for prevention of damage
AssigneeFairchild Korea Semiconductor Ltd.
InventorsJin-Tae Kim, Shanmei Li, Jongmu Lee
Life of this patent
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Abstract
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.
Claims21
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.
1 more element
A converter comprising:
- a main switch for performing a switching operation in response to a first control signal;
- an auxiliary switch, connected between the main switch and a ground, for performing a switching operation in response to a second control signal having a different phase from the first control signal;
- a transformer including a primary coil and a secondary coil connected to an output end, and transforming an input voltage into an output voltage by the switching operations of the main switch and the auxiliary switch;
- and
- a switch controller for generating the first control signal and the second control signal by using a feedback voltage corresponding to the output voltage and a voltage of a signal corresponding to a current flowing to the primary coil, and increasing a turn-on time of the auxiliary switch to keep the auxiliary switch turned on by determining to turn off the auxiliary switch after a maximum turn-on duration of the auxiliary switch has elapsed when the voltage of the signal corresponding to the current flowing to the primary coil is greater than a reference voltage.
2 more elements
Dependencies are inferred from the claim text.