Leadtrend Technology Corporation

Ming Chang Tsou

Meng Jen Tsai

Chih Chi Chang

Chao-Chih Lin

Pao-Chu Chou

A power controller provides a PWM signal to a power switch in response to a compensation signal to control the power switch, the compensation signal generated in response to an output voltage of a power converter. The power controller is configured to provide a maximum switching frequency limiting a switching frequency of the PWM signal. The power controller jitters the maximum switching frequency, making the maximum switching frequency have a first average switching frequency and a first variation ratio when the compensation signal is a first compensation value, and have a second average switching frequency and a second variation ratio when the compensation signal is a second compensation value. The first average switching frequency is higher than the second average switching frequency, and the second variation ratio is larger than the first variation ratio.

Switching-mode power supplies and power controllers capable of jittering switching frequency

A power controller disclosed is for the use of a power converter with an inductive to regulate an output power source. The power controller has a PWM signal generator and a jitter inducer. The PWM signal generator controls a power switch to generate consecutive switching cycles. In each switching cycle the PWM signal generator controls a peak to regulate the output power source, and the peak is capable of representing a current flowing through the inductive device. The jitter inducer, connected to the PWM signal generator, is for altering the peak, so as to make a difference between two consecutive peaks. The difference has a sign and a magnitude. The jitter inducer makes the sign changed switching cycle by switching cycle.

Power controllers with frequency jittering, and control methods thereof

Herein is disclosed a control method suitable for a switching mode power supply. A power switch is controlled according to a clock signal to transfer electrical energy from an input power source to an output power source. A feedback signal is provided in response to an output voltage of the output power source. A clock signal is generated in response to the feedback signal and an input voltage of the input power source. The clock signal has a clock frequency determining a switching frequency of the power switch. When the feedback signal exceeds a relatively-high level, the clock frequency increases in response to decrease to the input voltage. When the feedback signal is below a relatively low level, the clock frequency is independent from the input voltage.

Power controllers and control methods thereof for switching mode power supplies

Control methods and related power controllers diminish audible noise in a power supply capable of performing valley switching. The power supply has an inductive device and a power switch. When the power switch is OFF, a winding voltage of the inductive device oscillates to provide an oscillation signal with at least one signal valley. An occurrence number of the signal valley is detected, and is compared with a lock number. When the occurrence number and the lock number fit a predetermined condition, the power switch is turned ON to start a cycle time at a start moment. Whether the start moment falls within an expectation window is checked. The lock number is changed if the start moment falls outside of the expectation window.

Switching-mode power supplies capable of operating at valley switching, and relevant control methods

A power converter provides a dummy load to lower an output voltage under a light-load or no-load condition. The power converter has a primary winding and a secondary winding isolated from each other. The secondary winding can de-energize to provide the output voltage at an output node for powering a load. The winding voltage at across the secondary winding is sensed to provide a non-switching time, which is checked if it exceeds a predetermined reference time. The output voltage is compared with a predetermined voltage. A discharge current is provided as the dummy load to drain from the output node and to lower the output voltage if the on-switching time exceeds the predetermined reference time and the output voltage exceeds the predetermined voltage.

Dummy load controllers and control methods for power supplies capable of quickly lowering output voltage at output node

A power controller with over power protection is disclosed, capable of providing a pulse-width-modulation signal to control a power switch. The power controller comprises a pulse width modulator, first and second oscillators, and an over power detector. The pulse width modulator generates the pulse-width-modulation signal. The first oscillator is coupled to the pulse width modulator, for determining a cycle time of the pulse-width-modulation signal. The second oscillator, independent from the first oscillator, determines a maximum over power duration. The over power detector detects the occurrence of an over power event. When the over power event lasts for the maximum over power duration, the pulse-width-modulation signal switches OFF the power switch constantly.

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Zhubei, Taiwan

Ming Chang Tsou