Abstract: A voltage conversion apparatus is provided. A leakage inductance energy recovery circuit is coupled to a primary side auxiliary winding and a control circuit, and recovers leakage inductance energy of a transformer circuit to supply an operating power to the control circuit. Before a main switch is turned on the next time, leakage inductance energy recovered previously is used to lower a cross-voltage of the main switch, so that transient loss of conduction of the main switch is eliminated or reduced, and circuit efficiency is improved.

Abstract: A pulse width modulation control circuit and a control method of a pulse width modulation signal are provided. A counter circuit generates a count value according to a phase-locked loop clock, and resets the count value according to a transition point of a synchronization signal. A comparison circuit compares the count value with a duty ratio set value, and sets the pulse width modulation signal to a high level while the count value is less than the duty ratio set value.

Abstract: An LED backlight system and an LED control circuit are provided. The LED backlight system includes an LED string and the LED control circuit. The LED control circuit includes an LED driver, a switching circuit and an abnormality detecting circuit. The LED driver is configured to generate a control signal. The switching circuit controls a current flowing through the LED string in response to the control signal. The abnormality detecting circuit is configured to detect a voltage or the current of a first end of the LED string. When the voltage or the current of the first end of the LED string is less than or equal to a threshold value, the abnormality detecting circuit turns off the switching circuit, and the abnormality detecting circuit detects an impedance of the first end of the LED string to determine an abnormal state of the LED string.

Abstract: A light emitting diode driving device and a light emitting diode backlight module are provided. A current is provided to a filter circuit by a controllable current source controlled by a dimming signal, so that the filter circuit generates a corresponding dimming voltage to control current flowing through a LED unit to dim the LED unit.

Abstract: A light emitting diode driving device and a light emitting diode backlight module are provided. A current is provided to a filter circuit by a controllable current source controlled by a dimming signal, so that the filter circuit generates a corresponding dimming voltage to control current flowing through a LED unit to dim the LED unit.

Abstract: A power conversion apparatus including a synchronous rectification (SR) transistor, a SR controller and a snubber circuit is provided. The SR controller is coupled to the SR transistor to control the SR transistor. A ground terminal of the SR controller is coupled to a source terminal of the SR transistor, and a power terminal of the SR controller is coupled to a system voltage. A first terminal of the snubber circuit is coupled to a drain terminal of the SR transistor. A second terminal of the snubber circuit is coupled to the power terminal of the SR controller. The snubber circuit obtains power from the drain terminal of the SR transistor and provides the system voltage accordingly.

Abstract: A power conversion apparatus and a synchronous rectification (SR) circuit thereof are provided. The power conversion apparatus includes a transformer and the SR circuit. A primary winding of the transformer receives an input voltage. A secondary winding of the transformer provides an output voltage to an output terminal. The SR circuit includes a SR transistor and a SR controller. The SR transistor is coupled between the secondary winding and the output terminal and controlled by a control signal. The SR controller is coupled to the SR transistor to receive a first detecting signal, and generates the control signal according to the first detecting signal. When the SR controller detects that the SR circuit is abnormal, the SR controller generates the controller signal to keep the SR transistor at an on state so as to perform an abnormal protection on the SR circuit.

Abstract: A power conversion apparatus and a synchronous rectification (SR) circuit thereof are provided. The power conversion apparatus includes a transformer and the SR circuit. A primary winding of the transformer receives an input voltage. A secondary winding of the transformer provides an output voltage to an output terminal. The SR circuit includes a SR transistor and a SR controller. The SR transistor is coupled between the secondary winding and the output terminal and controlled by a control signal. The SR controller is coupled to the SR transistor to receive a first detecting signal, and generates the control signal according to the first detecting signal. When the SR controller detects that the SR circuit is abnormal, the SR controller generates the controller signal to keep the SR transistor at an on state so as to perform an abnormal protection on the SR circuit.

Abstract: A power conversion apparatus and a synchronous rectification (SR) controller thereof are provided. The SR controller includes a first control circuit, a second control circuit, a pull-up circuit and a pull-down circuit. The first control circuit generates a pull-up control signal and a first pull-down signal according to a drain voltage of an SR transistor and a first voltage. The second control circuit compares the drain voltage with a second voltage to generate a second pull-down signal, and selects one of the first pull-down signal and the second pull-down signal as a pull-down control signal. The pull-up circuit and the pull-down circuit regulate a driving voltage on a gate terminal of the SR transistor in response to the pull-up control signal and the pull-down control signal respectively.

Abstract: A power conversion apparatus and a synchronous rectification (SR) controller thereof are provided. The SR controller includes a first control circuit, a second control circuit and a third control circuit. The first control circuit compares a drain voltage on a drain terminal of a SR transistor with a first voltage. When the drain voltage is lower than the first voltage, the first control circuit outputs a driving voltage to turn on the SR transistor. The second control circuit generates the driving voltage according to the drain voltage and a second voltage so as to control the SR transistor. The third control circuit compares the drain voltage with a third voltage. When the drain voltage is higher than the third voltage, the third control circuit outputs the driving voltage to turn off the SR transistor.

Abstract: A power conversion apparatus is provided. A detecting circuit detects a current flowing into a boot voltage input pin and converts the current into a corresponding detecting voltage. An adjusting signal generating circuit generates an adjusting signal according to the detecting voltage. A control circuit adjusts control parameters thereof according to the adjusting signal.

Abstract: A power conversion apparatus is provided. A detecting circuit detects a current flowing into a boot voltage input pin and converts the current into a corresponding detecting voltage. An adjusting signal generating circuit generates an adjusting signal according to the detecting voltage. A control circuit adjusts control parameters thereof according to the adjusting signal.

Abstract: A power conversion apparatus including a flyback power conversion circuit, a control chip and a detection auxiliary circuit is provided. The flyback power conversion circuit receives and converts an input voltage into a DC output voltage. The control chip generates a PWM signal in response to a power supplying requirement to control the operation of the flyback power conversion circuit, wherein the control chip has a single multi-function detection pin. The detection auxiliary circuit assists the control chip to obtain a first detection voltage via the multi-function detection pin, such that the control chip performs a detection of an over temperature protection (OTP) and a detection of an over voltage protection (OVP) synchronously according to the first detection voltage. The first detection voltage is related to the DC output voltage or a thermal voltage of an environment temperature.

Abstract: Determine the duty cycle of the pulse width modulation signal to derive the voltage value of the alternating current voltage when the power supply is in the peak power working status. The voltage value of the alternating current voltage is determined as high if the duty cycle of the pulse width modulation signal is lower than the predetermined duty cycle. At this time, the limit detection voltage of the pulse width modulation controller is suppressed to protect the transistor switch, and the power supply can still provide the load apparatus with enough power. The power supply does not need any alternating current voltage detection circuit. The voltage value of the alternating current voltage is derived by determining the duty cycle of the pulse width modulation signal.

Abstract: A power conversion apparatus including a flyback power conversion circuit, a control chip and a detection auxiliary circuit is provided. The flyback power conversion circuit converts an input voltage into a direct current (DC) output voltage. The control chip generates a pulse width modulation (PWM) signal for controlling operations of the flyback power conversion circuit. The detection auxiliary circuit assists the control chip in obtaining a first detection voltage via a multi-function detection pin of the control chip within an enabling period of the PWM signal, so as to execute an over current detection according to the first detection voltage. Besides, the detection auxiliary circuit assists the control chip in obtaining a second detection voltage via the multi-function detection pin within a disabling period of the PWM signal, so as to execute a valley voltage detection according to the second detection voltage.

Abstract: A power conversion apparatus is provided. The power conversion apparatus includes a transformer, a synchronous rectification (SR) transistor and an SR control circuit. A first terminal of a primary side of the transformer receives an input voltage. A first terminal of a secondary side of the transformer provides an output voltage to a load. A first drain/source terminal of the SR transistor is coupled to a second terminal of the secondary side of the transformer. A second drain/source terminal of the SR transistor is coupled to a first ground terminal. A gate terminal of the SR transistor receives a control signal. The SR control circuit receives a signal of the first drain/source terminal of the SR transistor to determine statuses of the load and generate the control signal. When the load is a light load, the SR control circuit enters a power-saving mode and turns off the SR transistor.

Abstract: A power conversion apparatus and a protection method of the power conversion apparatus while a feedback current signal of the power conversion apparatus is abnormal are provided. The protection method includes a step of stopping switching a power switch if a duty cycle of a pulse width modulation signal is continuously greater than a preset duty cycle for at least one signal cycle and a voltage of a current sensing signal is smaller than a preset voltage level during the at least one signal cycle.

Abstract: A power conversion apparatus includes a power conversion circuit, a synchronous rectification transistor, a synchronous rectification control circuit, a feedback circuit, and a cable loss compensation circuit. The power conversion circuit converts an input voltage into an output voltage and provides it to a load. The synchronous rectification transistor is coupled in series to a current path on a secondary side of the power conversion circuit and switched according to a synchronous rectification control signal. The synchronous rectification control circuit generates the synchronous rectification control signal for controlling the switching of the synchronous rectification transistor. The feedback circuit generates an output indication current associated with the output voltage.

Abstract: A power conversion apparatus including a power conversion circuit, a light-emitting unit and a control chip is provided. The control chip has a multi-function pin and a feedback pin, where the multi-function pin and the feedback pin respectively receive a dimming signal and a feedback signal reflecting an output current of the light-emitting unit, and the control chip determines whether to generate a PWM signal to a power switch of the power conversion circuit according to the dimming signal and the feedback signal based on a duty ratio of the dimming signal.

Abstract: A LED backlight module including a LED string and a driving apparatus is provided. The driving apparatus comprises a sensing resistor, an adjustable voltage-divider circuit, a comparator, a power converter and a control circuit. The sensing resistor is coupled between a cathode of the LED string and a ground potential and generates a feedback voltage. The adjustable voltage-divider circuit generates a reference voltage according to a dividing ratio which is controlled by a first signal set and a second signal set. The comparator compares the feedback voltage and the reference voltage, and generates a control signal accordingly. The power converter provides a DC voltage to an anode of the LED string according to the control signal. The control circuit counts a disable period of a dimming signal to generate the first signal set, and counts an enable period of the dimming signal to generate the second signal set.