Leadtrend Technology Corporation

Mao-Shih Li

Ching-Tsan Lee

Ming-Chang Tsou

Hung-Ching Lee

Yao-Tsung Chen

San-Yi Li

Pai-Feng Liu

Hsin Hung Lu

Chin-Ho Wu

Hsien-Te Huang

Chih-Nan Hsia

San Yi Li

A power supply is configured to limit its output power, converting an input voltage on a primary side into a bus voltage on a secondary side. A current-sense resistor detects a bus current output from the power supply to provide a current-sense signal. A bus switch is electrically connected to a secondary winding on the secondary side, configured to selectively supply power to the bus voltage. A power delivery controller controls the bus switch in response to the current-sense signal and a power detection signal on the secondary side. The power delivery controller provides a power threshold in response to the bus voltage, compares the power detection signal with the power threshold, and turns off the bus switch to stop supplying power to the bus voltage if the power detection signal exceeds the power threshold, thereby limiting the output power of the power supply.

Power supplies with limited power protection and relevant control methods

A secondary controller applied to a secondary side of a power converter includes a detector and a standby signal generation circuit. The detector is used for detecting a first signal and a second signal of a universal serial bus device, and a frequency of a synchronization signal corresponding to a primary side of the power converter. The standby signal generation circuit is coupled to the detector for delaying a first predetermined time to generate a standby signal to a primary controller of the primary side of the power converter when the detector fails to detect the first signal and the second signal, and the frequency of the synchronization signal is less than a first predetermined frequency, wherein the primary controller enters a standby mode according to the standby signal.

Standby power control for a flyback USB device using primary side frequency and data port sensing

Disclosed are LED controllers for dimming. An LED controller includes a current driver, a pulse-width modulator, a feedback circuit, and a decoupling circuit. The current driver, selectively in response to a dimming signal, causes a driving current flowing through one LED string. The dimming signal is capable of defining a dimming ON period and a dimming OFF period. The pulse-width modulator generates a PWM signal to control a power switch, in order to buildup a driving voltage at a power node of the LED string. The PWM signal is generated in response to a compensation signal. The feedback circuit, based upon a feedback voltage from the light emitting device, drives a compensation capacitor to generate the compensation signal. The decoupling circuit defines a decoupling period at the start of the dimming ON period and causes the feedback circuit not driving the capacitor during the decoupling period.

LED controllers for dimming at least one LED string

A control circuit suitable for a power supply. The power supply has a transformer with a primary winding and a secondary winding magnetically coupled to each other. The transformer is configured to transfer electric energy from a primary side to a secondary side and to build an output power source in the secondary side. The control circuit has a primary-side controller and a secondary-side controller. The primary-side controller is in the primary side, configured to control a current through the primary winding. In the secondary side, the secondary-side controller is powered by the output power source and configured to provide a command code with several command bits sequentially transmitted to the primary-side controller, so as to set an operation mode that the primary-side controller operates in.

Power supplies and control methods suitable for sequentially transmitting command bits from secondary side to primary side

A control method is disclosed for light dimming. A dimming condition signal is provided to represent whether a light emitting device is expected to be emitting light. The duration when the dimming condition signal is at a logic value indicating the light emitting device is emitting light is a dimming-ON time, in which a close loop is provided to make a power converter convert electric energy to the light emitting device such that the light emitting device is capable of emitting light. A power-ON time is the duration when the power converter converts electric energy to the light emitting device. When the dimming-ON time ends and is less than a minimum power-ON time, the power converter continues converting the electric energy to the light emitting device so as to keep the power-ON time not less than the minimum power-ON time.

Growing community of inventors

Zhubei, Taiwan

Mao-Shih Li