Feedback driving circuit

Abstract

The invention relates to a feedback driving circuit. The circuit includes a channel LED current driving circuit module (003) used for receiving matching current of at least two LED channels according to received digital signals, at least two sampling and holding circuit modules (001) used for acquiring and holding node voltage at one end of each of the least two LED channels respectively, a channel feedback voltage selection and error amplifier module (002) used for determining minimum voltage from voltage outputted from the sampling and holding circuit modules (001) and amplifying the minimum voltage and then outputting the amplified minimum voltage, and a voltage boosting driving-stage circuit module (006) used for performing adaptive adjustment on node voltage at the other ends of the least two LED channels according to the output voltage of the channel feedback voltage selection and error amplifier module (002). With the feedback driving circuit of the invention adopted, an external voltage splitting feedback resistor can be omitted under the condition that the area of a chip is not increased, and the voltage stability of an external circuit is maintained, and the output voltage of the external circuit is optimal, and the utilization efficiency of a power source is improved.

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 BoostLED 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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