Abstract: A power conversion apparatus and an over current protection (OCP) method thereof are provided. The OCP method includes generating a pulse-width-modulation (PWM) signal according to a loading status of an electronic device, so as to switch a power switch in the power conversion apparatus and thus making the power conversion apparatus providing an output voltage to the electronic device; generating an OCP reference signal with variable slope according to a feedback signal related to the loading status of the electronic device and a system operation voltage of a PWM controller chip in the power conversion apparatus that is used for generating the PWM signal; and comparing a sensing voltage corresponding to a current following through the power switch on a resistor, and the OCP reference signal with variable slope to determine whether to activate an OCP mechanism to control the PWM controller chip whether to generate the PWM signal.

Abstract: A light-emitting-diode (LED) driving apparatus is provided, and which includes a power switch having a first terminal coupled to a first node and a second terminal coupled to a second node, wherein an LED string is coupled between a DC voltage and the first node; a first resistor coupled between the second node and a ground potential; and a control chip for generating a driving signal in response to a voltage on the second node and a bandgap voltage during an activation phase of the LED driving apparatus, so as to switch the power switch and thus making the LED string to be operated under a constant current for producing light, and further comparing a detection voltage obtained in response to a voltage on the first node with a predetermined voltage, so as to stop generating the driving signal when the detection voltage is greater than the predetermined voltage.

Abstract: A light emitting diode (LED) driving apparatus is provided, and which includes a first operational amplifier (OPA) having a positive input terminal receiving a predetermined voltage related to a current flowing through an LED string; a first resistor having a first end coupled to a negative input terminal of the first OPA and a second end coupled to a ground; a power transistor having a gate coupled to an output of the first OPA, a drain coupled to a cathode of the LED string and a source coupled to the first end of the first resistor; an error amplifier having a first input terminal coupled to the gate of the power transistor, a second input terminal receiving a reference voltage and an output terminal outputting a control voltage; and a power conversion stage providing a DC voltage to an anode of the LED string according to the outputted control voltage.

Abstract: A power conversion apparatus and a brown-out protection method are provided. The brown-out protection method includes sampling a rectification signal relating to an AC voltage received by the power conversion apparatus by adopting a discrete sampling means; and when a peak value of the sampled rectification signal has reached to a predetei mined value within a predetermined duration, making a pulse width modulation (PWM) control chip in the power conversion apparatus provide a PWM signal to switch a power switch in the power conversion apparatus, and thereby making the power conversion apparatus provide an output voltage to an electronic device; otherwise, making the PWM control chip to stop providing the PWM signal.

Abstract: A light emitting diode (LED) driving apparatus is provided, which includes a power conversion circuit for receiving and converting an input power so as to generate a DC voltage to simultaneously drive a plurality of LED strings arranged in parallel; and a plurality of current regulation chips each having a single regulation channel and respectively corresponding to the LED strings, wherein an ith current regulation chip is only used for regulating a current flowing through an ith LED string, where i is a positive integer.

Abstract: A power conversion apparatus and an over current protection (OCP) method thereof are provided. The OCP method includes generating a pulse-width-modulation (PWM) signal according to a loading status of an electronic device, so as to switch a power switch in the power conversion apparatus and thus making the power conversion apparatus providing an output voltage to the electronic device; generating an OCP reference signal with variable slope according to a feedback signal related to the loading status of the electronic device and a system operation voltage of a PWM controller chip in the power conversion apparatus that is used for generating the PWM signal; and comparing a sensing voltage corresponding to a current following through the power switch on a resistor, and the OCP reference signal with variable slope to determine whether to activate an OCP mechanism to control the PWM controller chip whether to generate the PWM signal.

Abstract: A frequency-jitter-controller for a power-converter is provided, and which includes a first and a second capacitance units, a first and a second charge-discharge control units, a comparing unit and a control unit. Both capacitance units are charged to a crossing-voltage during a charging phase and discharged to a reference voltage and a clamp voltage respectively during a discharging-phase in response to operations of both charge-discharge control units. The comparing unit outputs a pulse signal, compares voltages of both capacitance units during the charging phase, and compares the voltage of the first capacitance unit and the reference voltage during the discharging phase. The control unit generates a frequency jitter control signal according to the pulse signal to adjust a rising rate of the voltage on the second capacitance unit, so as to change a frequency of the pulse signal, and thus reduce EMI generated by switching switch-elements in the power-converter.

Abstract: A power conversion apparatus with adjustable leading-edge-blanking (LEB) time and an over current protection (OCP) method thereof are provided. In the OCP method, a pulse-width-modulation (PWM) signal is generated according to the loading status of an electronic device to switch a power switch in the power conversion apparatus and thus the power conversion apparatus to supply an output voltage to the electronic device. A variable or fixed LEB signal is generated according to the PWM signal and the rising and falling edges of a spike signal induced at turn-on instant of the power switch. The PWM signal is constantly/continuously generated to switch the power switch during an enabling period/phase of the variable or fixed LEB signal, and whether an over current is produced in the power conversion apparatus is constantly detected to determine whether to activate an OCP mechanism during a disabling period/phase of the variable or fixed LEB signal.