Leadtrend Technology Corporation

Altek Corporation

Yuan-Wen Chang

Yi-Shan Chu

Ming-Nan Chuang

Ren-Yi Chen

Yu-Bin Wang

Yu-Chuan Liu

Yi-Lun Shen

Da-Chun Wei

Chun-Teh Chen

A method for controlling voltage crossing a power switch of a switched-mode power converter includes the steps of: controlling a switch frequency of the power switch of the switched-mode power converter to a first frequency as activating the switched-mode power converter; and then changing the switch frequency of the power switch to a second frequency after the switched-mode power converter is activated for a predetermined time; wherein the first frequency is lower than the second frequency.

Control circuit of a switched-mode power converter and method thereof

A control circuit for use in a power converter has a multi-function terminal, a current comparator circuit, and an under-voltage detection circuit. The current comparator circuit compares current flowing through a power switch of the power converter with a reference value through the multi-function terminal when the power switch is on, and turns the power switch off when the current reaches the reference value. The under-voltage detection circuit determines whether an input voltage of the power converter is less than a predetermined value through the multi-function terminal when the power switch is turned off.

Power converter with control circuit and related control method

A control method for adjusting leading edge blanking time in a power converting system is disclosed. The control method includes: receiving a feedback signal relative to a load connected to an output terminal of the power converting system; determining the leading edge blanking time to be a first value if the feedback signal has a magnitude about a first voltage; and determining the leading edge blanking time to be a second value if the feedback signal has a magnitude about a second voltage, wherein the first value is smaller than the second value, and the first voltage is greater than the second voltage.

Control method for adjusting leading edge blanking time in power converting system

A control circuit for adjusting leading edge blanking time is disclosed. The control circuit is applied to a power converting system. The control circuit adjusts a leading edge blanking time according to a feedback signal relative to a load connected to the output terminal of the power converting system. An over-current protection mechanism of the power converting system is disabled within the leading edge blanking time.

Control circuit for adjusting leading edge blanking time and power converting system using the same control circuit

A high voltage charging circuit is provided with the ability of rapid charging. The circuit is composed of a turn-on control circuit, a turn-off control circuit and a transistor. The turn-on control circuit is adopted to set a turn-on time of a transistor such that the transformer may store magnetic energy, while the turn-off control circuit is used to set a turn-off time of the transistor such that the transformer may release the magnetic energy to charge a high voltage capacitor. Smaller inductance reduces the turn-on time of the power transistor owing to the maximum current of the primary side of the transformer. Therefore, a small-sized transformer may be employed to reduce the volume of the charging circuit with nonoccurrence of saturation.

High voltage charging circuit

A pulse-width-modulation control circuit of a switching-mode power converter with a primary-side feedback control is disclosed. The switching-mode power converter includes a transformer, a power switch, a current sensing resistor and the pulse-width-modulation control circuit. The transformer includes a primary-side winding, a secondary-side winding and an auxiliary winding. The pulse-width-modulation control circuit includes a sample and hold circuit, a transconductor circuit, an error amplifier and a pulse-width-modulation generator.

Switching-mode power converter and pulse-width-modulation control circuit with primary-side feedback control

A high voltage charging circuit includes an activation control circuit, an inactivation control circuit and a power transistor. The activation control circuit is used for controlling an ON time period of the power transistor to enable the transformer to store excited-magnetic energy; the inactivation control circuit is used for controlling an OFF time period of the power transistor to make the transformer to release the excited-magnetic energy and use the excited-magnetic energy to charge the high voltage capacitor. Since the user can select a smaller Lp to keep constant the maximum value Ifor the primary side current I, the period tcan be made smaller as well, which means that a transformerwith a smaller volume can be utilized to reduce the entire size of the high voltage charging circuit.

High voltage charging circuit for charging a high voltage capacitor

A capacitance charge device with adjustable clamping voltage is disclosed in the invention, which includes a high-farad capacitance and a power supply device for charging to the high-farad capacitance. In addition, a switch device is connected between the power supply device and the capacitance, and through the on/off operations of the switch device, the on/off conductions between the power supply device and the capacitance can be controlled. Besides, a clamping circuit is connected between the switch device and the capacitance and also connected to the output terminal of the power supply device. In addition, the clamping circuit has a clamping voltage, which can be compared with the actual voltage so as to control the on/off operations of the switch device and in turn control the on/off conductions between the power supply device and the capacitance. In addition, the invention can constrain the battery voltage in the clamping voltage of the clamping circuit. By doing so, the system can be ensured not to be down because of a sudden tremendous voltage drop of the battery, and the clamping voltage is adjustable according to the variations in product design.

Growing community of inventors

Hsin-Chu, Taiwan

Yuan-Wen Chang