Patent ID: 9058777
Filing Date: 2015-06-16
Classification: G09G,H05B

Abstract:
1. A LED backlight driving circuit, comprising: a boost circuit for converting an input voltage to a needed output voltage and for providing the output voltage to at least one LED strings; a follower circuit connecting to a negative end of the LED string, the follower circuit configured for monitoring a negative end voltage of the LED string and for generating a follower voltage according to the negative end voltage, and the follower voltage couples with a reference voltage module; and the reference voltage module connecting to a reference voltage and the follower circuit, and the reference voltage module adjusts the output voltage according to the follower voltage generated by the follower circuit; wherein the follower circuit generates a first follower voltage coupling with the reference voltage module upon detecting that the negative end voltage of the LED string is smaller than a standard value, and the reference voltage module increases the output voltage according to the first follower voltage generated by the follower circuit, and the follower circuit generates a second follower voltage coupling with the reference voltage module upon detecting that the negative end voltage of the LED string is larger than the standard value, and the reference voltage module decreases the output voltage according to the second follower voltage generated by the follower circuit; the follower circuit comprises a comparison circuit and a voltage control circuit, the comparison circuit is for detecting the negative end voltage of the LED string and for generating a control signal, and the voltage control circuit is for generating the follower voltage according to the control signal, and the follower voltage couples with the reference voltage module; and the comparison circuit comprises a first comparator and a second comparator, wherein an inversed input of the first comparator receives a first reference voltage, an non-inverting input of the second comparator receives a second reference voltage, the non-inverting input of the first comparator connects to the inversed input of the second comparator and then connects to the negative end of the LED string, output ends of the first comparator and the second comparator generate signals for controlling the voltage control circuit to generate the follower circuit coupling with the reference voltage module, and wherein the first reference voltage is larger than the second reference voltage.