High-power LED driver

Abstract

The invention discloses a high-power LED driver comprising a boost-buck switching converter which takes a first pole terminal and a second pole terminal of an inductor as output ends, a current detector for detecting current value of the inductor in the switching converter and a controller for receiving a signal of the current detector. A cycle control circuit is arranged in the boost-buck switching converter for receiving a control signal of the controller to maintain the current of the inductor within a certain threshold; the cycle control circuit comprises a first power switch tube which isconnected between the second pole terminal of the inductor and a ground terminal and a second power switch tube which is connected between the first pole terminal and the second pole terminal; and the controller comprises a first control terminal and a second control terminal for respectively controlling the first power switch tube and the second power switch tube to turn on and turn off. Compared with the traditional driver, the LED driver reduces a power element and can provide stable current for an LED and achieve a higher dimming ratio than the traditional structure by being matched withthe corresponding control strategy.

Description

technical field [0001] The invention relates to the field of power electronics design, in particular to a high-power light-emitting diode (LED) driver. Background technique [0002] White light LED is called "the new light source of the 21st century" because of its outstanding advantages such as long life and energy saving. In addition, due to its three-wavelength full-color and high lumen characteristics, it is very suitable for use as a display backlight. [0003] In order for the LED to work efficiently and stably, it must be powered by a dedicated drive controller. Due to the characteristics of the LED itself, current LED drivers usually use current control, that is, to maintain stable brightness and color by constant average current flowing through the LED. Therefore, the overall development trend of LED drivers is: to further improve the conversion efficiency and output power under the premise of ensuring the output current control accuracy; to reduce the number of p...

AI Technical Summary

Problems solved by technology

[0005] But this dimming method has disadvantages, such as Figure 4 As shown, firstly, when the PWM dimming signal control is “on”, if the peak current control is adopted, affected by the control loop, the LED current needs to go through several switching cycles (that is, the signal cycle for controlling the power switch tube) to reach the rated current value; Secondly, the switching signal is not synchronized with the PWM dimming signal

Due to the existence of the above two problems, the minimum "on time" of the PWM dimming signal is 3-5 switching cycles, which limits the dimming ratio and dimming frequency

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