Other

Jianbo Sun

Kun Cheng

Gang Shi

Zutao Liu

Fang Liu

Yun Lu

Xuguang Zhang

Zhengdong Zhang

An embodiment of the present invention relates to a method for detection of short circuit conditions in an LED array having one or more LED strings, each of which includes one or more LED devices. The method includes determining a minimum voltage that is the lowest of voltages associated with cathode terminals of the one or more LED strings. The method also includes determining if said minimum voltage is between a lower limit voltage and an upper voltage limit. If said minimum voltage is between the lower limit voltage and the upper voltage limit, then a result of a short circuit testing can be considered valid. Here, the short circuit testing includes comparing a sampled voltage associated with a cathode voltage of one of the LED strings with a short-circuit reference voltage.

Method and circuits for short-circuit protection of LED systems

The present invention relates to a parallel light emitting diode ('LED') drive circuit and provides a drive circuit configured to drive a parallel array of LEDs. The drive circuit comprises: a plurality of switches, a plurality of sampling resistors, and a plurality of chopper amplifiers. Each switch is coupled to a respective LED in the LED array. Each chopper operational amplifier configured to receive a reference voltage and a switching control signal and generate an input offset voltage. Each chopper operational amplifier includes a differential amplifier including an input transistor pair and a current mirror transistor pair, of which the electrical positions can be reserved when the switching control signal is switched between a first state and a second state, wherein the offset voltage, which causes the lightness mismatching in a parallel LED circuit, can be cancelled.

Drive circuit for parallel array of light emitting diodes

The present invention relates to a parallel light emitting diode ('LED') drive circuit and provides a drive circuit configured to drive a parallel array of LEDs. The drive circuit comprises: a switching control signal generator, a plurality of switches, a plurality of sampling resistors, and a plurality of chopper amplifiers. Each switch is coupled to a respective LED in the LED array. Each chopper operational amplifier configured to receive a reference voltage and a switching control signal generated by the switching control signal generator and generate an input offset voltage. Each chopper operational amplifier includes a differential amplifier including an input transistor pair and a current mirror transistor pair, of which the electrical positions can be reserved when the switching control signal is switched between a first state and a second state, wherein the offset voltage, which causes the lightness mismatching in a parallel LED circuit, can be cancelled.

Dynamically controllable drive circuit for parallel array of light emitting diodes

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Jianbo Sun