Leadtrend Technology Corporation

Grenergy Opto Inc.

Weltrend Semiconductor Inc.

Yi-Lun Shen

Yu-Yun Huang

Ren-Yi Chen

Da-Chun Wei

Wen-Chung Yeh

Yi-Shan Chu

Ming-Ying Kuo

Yuan-Wen Chang

A power control device includes a switch control circuit, a first resistor, a second resistor, a third resistor, a sense node, a first comparator, a second comparator, a transformation circuit, and a logic control circuit. The switch control circuit outputs a driving signal according to a set signal and a reset signal. The first resistor, the second resistor, and the third resistor generate a reference voltage according to a feedback current. The sense node receives a current sample voltage. The first comparator outputs a first control signal according to the current sample voltage and the reference voltage. The transformation circuit outputs a short detection voltage according to the current sample voltage. The second comparator outputs the second control signal according to the current sample voltage and the short detection voltage. The logic control circuit gate outputs the reset signal according to the first control signal and the second control signal.

Power control device capable of detecting the condition of the sensing resistor

A control circuit includes a set of alternating-current (AC) power receiver terminals, a rectification unit, a transistor, a switch, a detection unit, a comparison unit and a logic control circuit. The AC power receiver terminals receive and send external AC power to the rectification unit. The rectification unit outputs an operation voltage accordingly. The transistor is coupled between the rectification unit and the switch. The detection unit is coupled to the rectification unit to generate a first detection voltage and a second detection voltage according to the operation voltage. When the first detection signal is equal to the second detection signal, the comparison unit sends a comparison signal. The logic control circuit turns on the transistor and the switch if the comparison signal still has not been received after a predetermined time interval has elapsed.

Control circuit capable of detecting status of receiving power and decreasing voltage of capacitor accordingly

A controller for generating jitters in a quasi resonant mode includes a feedback pin, a voltage generation unit, a pulse generator, and a comparator. The feedback pin is used for receiving a feedback voltage from a secondary side of a power converter. The voltage generation unit is used for generating a first voltage according to the feedback voltage and a pulse. The pulse generator is used for generating the pulse when a control signal controlling a power switch of a primary side of the power converter is enabled. The comparator is used for controlling enabling and disabling of a switching signal according to the first voltage and a variable reference voltage. The variable reference voltage is monotonously swung within a predetermined range according to a digital signal.

Controller for generating jitters in a quasi resonant mode and method for generating jitters in a quasi resonant mode

A power controller provides a block time in response to an output current to an output load, and the block time determines a maximum switching frequency of a switching mode power supply. An exemplifying power controller has an output current estimator, a block time generator, and a pulse width modulator. The output current estimator provides a load representative signal in response to a discharge time of the inductive device and a current sense signal, wherein the current sense signal represents a current through an inductive device. The block time generator provides a block time based on the load representative signal. The pulse width modulator generates a pulse-width-modulation signal to control a power switch in response to a compensation signal, which is in response to the output voltage to the output load. The cycle time of the pulse-width-modulation signal is limited to be not less than the block time.

Switching mode power supply capable of providing a block time in response to an output current

A controller for generating jitters in a constant current mode of a power converter includes a current pin, an auxiliary pin, a constant current control unit, and a control signal generation unit. The current pin is used for receiving a primary side voltage determined according to a resistor and a primary side current flowing through the power converter. The auxiliary pin is used for receiving a voltage corresponding to an auxiliary winding of the power converter. The constant current control unit is used for generating an adjustment signal according to the primary side voltage, a discharge time corresponding to the voltage, and a reference voltage. The reference voltage has a predetermined range jitter voltage. The control signal generation unit is used for adjusting a period of a gate control signal according to the adjustment signal.

Controller for generating jitters in a constant current mode of a power converter and method thereof

Power controllers and related primary-side control methods are disclosed. A disclosed power controller has a comparator and an ON-triggering controller. The comparator compares a feedback voltage with an over-shot reference voltage. Based on an inductance-coupling effect, the feedback voltage represents a secondary-side voltage of a secondary winding. Coupled to the comparator, the ON-triggering controller operates a power switch at about a first switching frequency when the feedback voltage is lower than the over-shot reference voltage. The ON-triggering controller operates the power switch at about a second switching frequency when the feedback voltage exceeds the over-shot reference voltage. The second switching frequency is less than the first switching frequency.

Methods and power controllers for primary side control

A quasi-resonant (QR) converter introduces soft transition for valley switching and valley locking. One exemplifying QR converter is capable of performing valley switching, but has the valley switching in a specific signal valley of one switching cycle softly transit to the valley switching in another signal valley of a later switching cycle, via at least one switching cycle performing no valley switching.

Switching mode power supply capable of achieving soft transition for valley switching, or performing valley locking

Controllers and related control methods for a switched mode power supply are disclosed. The switched mode power supply has an inductive device and a power switch connected in series. An output current estimator in a controller is configured for receiving a current-sense signal representing an inductor current flowing through the inductive device and a discharge-time signal indicating a discharge time of the inductive device. The output current estimator generates a charge current in response to the discharge-time signal and the current-sense signal, thereby the charge current substantially corresponding to an output current that the switched mode power supply outputs to a load. The charge current is limited not to exceed a maximum value. A current limiter is configured for limiting the current-sense signal when the charge current is the maximum value.

Controllers and related control methods for generating signals representing an output current to a load in a switched mode power supply

Herein is disclosed a constant current control unit and a control method, for a switched mode power supply with primary side control. The switched mode power supply comprises a power switch and an inductive device. A reflective voltage of the inductive device is detected to generate a feedback voltage signal. By delaying the feedback voltage signal, a delayed signal is generated. According to the feedback voltage and the delayed signal, a discharge time of the inductive device is determined when the power switch is OFF. According to the discharge time and a current-sense signal, a maximum average output current of the switched mode power supply is stabilized. The current-sense signal represents a current flowing through the inductive device.

Constant current control units and control methods thereof for primary side control

Embodiments disclose control methods and control apparatuses for a switched mode power supply. The switched mode power supply comprises a current-controllable device. A driving current is provided to turn ON the current-controllable device. A conduction current passing through the current-controllable device is detected. The driving current is controlled according to the conduction current. The higher the conduction current the higher the driving current.

Control methods and apparatuses for switching mode power supplies

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

Disclosure includes control methods and power controllers with load compensation adapted for a power supply powering a load. A disclosed power controller comprises a converter and a control circuit. The converter converts the load signal at a first node to output a load-compensation signal at a second node. The load signal corresponds to an output power provided from the power supply to the load, and the converter includes a low-pass filter coupled between the first and second nodes. The control circuit is coupled to an inductive device via a feedback node, for controlling the output power to make a cross voltage of the inductive device approach a target voltage, based on a feedback voltage at the feedback node. The higher the load-compensation signal the higher the target voltage.

Control methods and power controllers with load compensation adapted for a power supply

The disclosure provides a power controller and related control method for a switch mode power supply operating in a quasi-resonant mode. The switched mode power supply has a power switch and an auxiliary winding. The power controller has a feedback pin connected to the auxiliary winding. A clamp circuit is connected to the feedback pin and configured for clamping a voltage at the feedback pin by providing a clamp current. A peak hold circuit is connected to the clamp circuit for generating a peak record substantially corresponding to a peak value of the clamp current. A valley detector is configured for providing an entry signal indicating a start of a voltage valley. A delay circuit provides a trigger signal a delay time after the entry signal is provided. The delay time varies in response to the peak record, and the trigger signal is capable of turning on the power switch.

Power controllers and control methods suitable for operating a switched mode power supply in quasi-resonant mode

Disclosed include a control circuit adapted for a power controller powered by an operation voltage. When the operation voltage exceeds an over-voltage reference, the power controller stops power conversion provided by a power converter. The control circuit comprises a slope detector detecting a variation slope of the operation voltage. When the variation slope exceeds a drop rate, the slope detector recovers the power conversion. When the power conversion is recovered the power controller compares the operation voltage with the over-voltage reference.

Control circuits and control methods for over voltage protection in power suppliers

A sample-and-hold circuit for generating a variable sample delay time of a transformer includes a discharge detection unit, a sample delay time generation unit, and a comparator. The discharge detection unit generates a first voltage according to a first turning-on signal and a first reference current. Length of the first turning-on signal is varied with a discharge time of a present period of the transformer. The sample delay time generation unit generates a second voltage according to the first turning-on signal and a second reference current. The comparator generates a sample signal to a control circuit of the transformer according to a first voltage corresponding to a previous period of the transformer and a second voltage corresponding to the present period of the transformer. The first reference current is K times the second reference current, and 0&#x3c;K&#x3c;1.

Growing community of inventors

Hsin-Chu, Taiwan

Yi-Lun Shen