Ampower Technology Co., Ltd.

Yong-Long Lee

Chin-Po Cheng

Cheng-Hung Tsai

Chien-Hung Chen

Ying-Tsun Wu

An exemplary light emitting diode (LED) driving system includes a direct current/direct current (DC/DC) converter, a detection circuit, a control circuit, a pulse width modulation (PWM) controller, and a current balance circuit. The DC/DC converter outputs a suitable direct current voltage to drive an LED array. The detection circuit detects cathode voltages of LED strings of the LED array. The control circuit generates and outputs a control signal to the PWM controller, and generates and outputs various adjusting signals. The current balance circuit adjusts current flowing through two of the LED strings, which have a minimum and a maximum detected cathode voltage, respectively. The current balance circuit includes switches. A related LED driving method is also provided.

LED driving system and method

A multi-lamp driving system includes a pulse width modulation (PWM) controller, transformers, a current difference detection circuit, a lighting detection circuit, a frequency scanning detection circuit, a frequency regulating circuit, and a duty cycle regulating circuit. The current difference detection circuit detects difference among current flowing through lamps to determine if the current fluctuates. The lighting detection circuit determines if the lamps are lit according to the current, and generates a lighting indication signal after the lamps are lit. The frequency scanning detection circuit determines if the multi-lamp driving system is in a frequency scanning process according to the lighting indication signal, and generates a frequency scanning indication signal if the multi-lamp driving system is in the frequency scanning process. The duty cycle regulating circuit regulates duty cycles of the PWM signals upon the condition that the current fluctuates and the multi-lamp driving system is in the frequency scanning process.

Multi-lamp driving system

A light emitting diode (LED) backlight driving system drives at least one LED array, and includes a boost power stage circuit, a controller, a multi-channel constant current driving circuit, a voltage dividing circuit, and an offset voltage generating circuit. The boost power stage circuit boosts direct current (DC) power signals to output driving voltage to drive the LED array. The multi-channel constant current driving circuit controls current flowing through the LED array, and outputs regulating voltage to the controller to regulate the driving voltage. The voltage dividing circuit divides the driving voltage to generate feedback voltage to send to the controller. The offset voltage generating circuit generates offset voltage to modify the feedback voltage according to at least one mode selection signal. The controller controls the driving voltage according to the modified feedback voltage and the regulating voltage.

Light emitting diode backlight driving system

A multi-lamp driving system includes a power supply and at least one balance transformer. Each balance transformer includes two cores, two primary windings, two secondary windings and two protection windings. Each primary winding is wrapped around a core and serially connected to a lamp to form a first circuit branch in parallel connection with each other. The first circuit branches are powered by the power supply. The Each secondary winding is wrapped around a core and connected to a primary winding. The two secondary windings are connected in series to form a short circuit loop. Each of the protection windings is wrapped around a core and connected to a primary winding. The protection windings are wrapped in opposite directions and connected in series to form a second circuit branch. The second circuit branch outputs voltage signals to the power supply when induced voltages crossing the protection windings are unequal.

A backlight driving system comprises an inverter module, a current balance module, a feedback module and an open-lamp protection detection module. The inverter module provides electrical signals to a plurality of lamps. The current balance module balances currents flowing through the plurality of lamps. The feedback module detects the current of the backlight and generates a feedback signal to the invert module accordingly. The open-lamp protection detection module detects voltage variations of the feedback transformer and generates a detection signal to the inverter module accordingly. The inverter module regulates the currents flowing through the plurality of lamps according to the feedback signal and determines one or more of the plurality of lamps are faulty according to the detection signal generated by the open-lamp protection detection module, and stops providing the electrical signals to the plurality of lamps.

Backlight driving system

A multi-lamp driving circuit for driving a plurality of lamps includes at least one power stage circuit, at least one transformer circuit, a balancing circuit, and a control circuit. The power stage circuit converts external electrical signals to alternating current (AC) signals. The transformer circuit is connected to the power stage circuit, to convert the AC signals to high voltage electrical signals capable of driving the lamps. The balancing circuit balances current flowing through the lamps, and includes a capacitor balancing circuit and a transformer balancing circuit. The control circuit is connected between the balancing circuit and the power stage circuit, to control output of the power stage circuit according to variation of the current flowing through the lamps.

Multi-lamp driving circuit

A light source driving device for driving a light source includes a power stage circuit, a transformer circuit, a control circuit, and a fault detecting circuit. The power stage circuit converts an external electrical signal to an alternating current (AC) signal. The transformer circuit is connected between the power stage circuit and the light source to convert the AC signal to a high voltage electrical signal adapted for driving the light source. The fault detecting circuit detects whether the light source is nonfunctional, and outputs a fault signal upon the condition that the light source is nonfunctional. The fault detecting circuit includes a voltage level comparison circuit and a variable-benchmark voltage circuit. The control circuit is connected between the fault detecting circuit and the power stage circuit to output a control signal to the power stage circuit based on the fault signal.

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Jhongli, Taiwan

Yong-Long Lee