FLYBACK BOOSTED CIRCUIT, LED BACKLIGHT DRIVE CIRCUIT AND LIQUID CRYSTAL DISPLAY

摘要

A flyback boosted circuit (20), comprising a transformer (21), a switch module (22), a drive module (23) and an output diode (Do). The transformer (21) has n primary coils (P1, P2) and one secondary coil (S); the switch module (22) has n switch elements (Q1, Q2); the dotted terminals of the n primary coils (P1, P2) are respectively connected to the n switch elements (Q1, Q2) on a one-to-one basis, and the other terminal of the primary coil (P1, P2) is connected to an input voltage (Vin); a dotted terminal of the secondary coil (S) is connected to the positive terminal of the output diode (Do), and the other terminal thereof is connected to the ground; an output capacitance (Co) is connected between the negative terminal of the output diode (Do) and the ground; and the drive module (23) provides control signals (DRV1, DRV2) respectively for the n switch elements (Q1, Q2) so as to control one of the n switch elements (Q1, Q2) to successively open during the time with a duty ratio D, and the sum of the duty ratios of the n switch elements (Q1, Q2) is D, where n is an integer greater than or equal to 2. The flyback boosted circuit (20) can effectively solve the problem of large heat productivity of the switch module (22) and can improve the output voltage range.