A feedback drive circuit

Abstract

The present invention relates to a feedback driving circuit, which comprises a channel LED current driving circuit module (003) for outputting matching currents of at least two LED channels according to a received digital signal; at least two sampling and holding circuit modules (001) , used to collect and hold the node voltages at one end of at least two LED channels respectively; the channel feedback voltage selection and error amplifier module (002) is used to determine the minimum voltage from the voltages output by the at least two sample and hold circuit modules (001), Amplify the minimum voltage and output it; the boosting driver stage circuit module (006) is used to perform a voltage step on the node voltages at the other ends of the at least two LED channels according to the channel feedback voltage selection and the output voltage of the error amplifier module (002). Adaptive adjustment. The invention ensures that the external voltage divider feedback resistance is saved without increasing the chip area, the voltage stability of the external circuit is maintained, the output voltage is optimized, and the utilization efficiency of the power supply is improved at the same time.

Description

technical field [0001] The invention relates to the field of design of boost-type high-voltage LED current drive circuits, in particular to a feedback drive circuit. Background technique [0002] LED backlights are used on small and cheap LCD panels; LED backlight structures are mainly divided into two types, series power supply and parallel power supply. The series power supply can use a lower constant current, but the input power needs to be raised to meet the series The total forward voltage level of the type power supply can drive the LED; the parallel type needs a higher constant current to drive, but reduces the demand for high voltage. Since the current of each LED in the same string is completely equal in the series power supply, there is no current matching problem; while in the parallel power supply, the current on each LED will have a certain deviation, and certain processing needs to be done on the current matching. [0003] The Boost LED driver in the prior art...

AI Technical Summary

Problems solved by technology

like Image 6 It is an LED output drive circuit with DAC current regulation function in the prior art. As shown in the figure, when setting different output currents, the VREF_LED voltage changes greatly. If the output drive current needs to change by 10 times, the VREF_LED voltage also needs to be changed. The change is 10 times. In order to ensure the normal operation of the maximum current, it is also necessary to increase the output voltage of Boost, which will also affect the utilization efficiency of this power supply.

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