Variable blanking frequency for resonant converters
AssigneeSemiconductor Components Industries, LLC
InventorsBonggeun Chung, Taesung Kim, Gwanbon Koo
Life of this patent
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Abstract
A power supply includes a transistor that is connected to a primary winding of a transformer. A controller controls a switching operation of the transistor by quasi-resonant switching. The controller receives a feedback voltage and adjusts the feedback voltage to adjust a blanking frequency, which is an inverse of a blanking time during which the transistor is prevented from being turned on. The controller turns on the transistor after expiration of the blanking time based on a level of a resonant ring.
Claims20
A circuit for controlling a power supply, the circuit comprising:
- a driver circuit configured to output a gate drive signal;
- and
- a blanking frequency generator circuit configured to generate a blanking signal based on a level of an input line voltage of the power supply and a feedback signal, the feedback signal having a value corresponding to an output voltage of the power supply, and the blanking signal being asserted in response to a rising edge of the gate drive signal to indicate a blanking interval;
- wherein the blanking signal operates to prevent the gate drive signal from being turned on when the blanking signal is asserted.
A circuit for controlling a power supply, the circuit comprising:
- a valley detect circuit configured to generate a valley detect signal indicating a valley, the valley corresponding to a low level of a resonant ring voltage;
- a blanking frequency generator circuit configured to generate a blinking signal according to an input line voltage of the power supply and a feedback signal, the feedback signal having a value corresponding to an output voltage of the power supply;
- an oscillator circuit to generate a clock signal according to the valley detect signal and a blanking signal;
- and
- a Pulse Width Modulation (PWM) circuit to generate a gate drive signal according to the clock signal and a current sense signal,
- wherein the blanking signal is asserted in response to a rising edge of the gate drive signal.
A method for controlling a power supply, the method comprising:
- generating, by a blanking frequency generator circuit, a blanking signal based on a level of an input line voltage of the power supply and a feedback signal, the feedback signal having a value corresponding to an output voltage of the power supply, and the blanking signal being asserted in response to a rising edge of a gate drive signal to indicate a blanking interval;
- and
- preventing the gate drive signal from being turned on when the blanking signal is asserted.
Dependencies are inferred from the claim text.