US Patent No. 10,143,054

LIGHT-EMITTING DIODE DRIVER


Patent No. 10,143,054
Issue Date November 27, 2018
Title Light-emitting Diode Driver
Inventorship Shen-Xiang Lin, Taipei (TW)
Hsuan-Hao Chien, Taipei (TW)
Chih-Jen Hung, Taipei (TW)
Assignee DAZZO TECHONOLOGY CORPORATION, Taipei (TW)

Claim of US Patent No. 10,143,054

1. A light-emitting diode (LED) driver, for driving a plurality of LED strings, the LED driver comprising:a dimming control circuit, for receiving a pulse width modulation (PWM) signal and a clock signal and outputting a dimming signal and a sampling signal, wherein a turn-on time of the sampling signal at high-level is shorter than a clock cycle of the clock signal;
a first error amplifier, coupled to the dimming control circuit, for receiving a feedback voltage, a reference voltage and the dimming signal respectively and outputting a compensating voltage;
a second error amplifier, coupled to the first error amplifier, for receiving the compensating voltage and a ramp signal respectively and outputting a pulse voltage;
a driving controller, coupled to the dimming control circuit and the second error amplifier, for receiving the dimming signal and the pulse voltage respectively and outputting a control signal;
an output stage, coupled to the driving controller, a first terminal of the plurality of LED strings, an input voltage and a ground terminal respectively, for receiving the control signal and the input voltage and generating an output voltage to the plurality of LED strings, wherein a plurality of LED currents flows from the first terminal of the plurality of LED strings to a second terminal of the plurality of LED strings respectively;
a minimum voltage selecting unit, coupled to the second terminal of the plurality of LED strings, for sensing a plurality of LED voltages at the second terminal of the plurality of LED strings and selecting a minimum LED voltage from the plurality of LED voltages; and
a switch unit, coupled to the dimming control circuit, the first error amplifier and the minimum voltage selecting unit respectively and controlled by the sampling signal, for selectively conducting the minimum voltage selecting unit and the first error amplifier, so that the first error amplifier receiving the minimum LED voltage from the minimum voltage selecting unit.