A local dimming constant current control circuit, driving power supply and TV

Abstract

The invention discloses a regional dimming constant current control circuit, a driving power supply and a TV set, wherein the regional dimming constant current control circuit is connected with an AC-DC conversion circuit, a main board and a backlight strip, and includes a dimming control module and a constant current drive module with a built-in boost control circuit and a multi-channel dimming switch tube; the dimming control module receives the drive signal and dimming signal output by the motherboard and transmits them to the constant current drive module. The drive signal boosts the first voltage output by the AC-DC conversion circuit to a preset voltage and then outputs it to the backlight light bar, and adjusts the gate duty cycle of the dimming switch tube of the corresponding channel according to the dimming signal, and then Adjust the current size of the corresponding channel. By adopting the built-in boost control circuit and the constant current drive module of the dimming switch tube, the structure of the regional dimming light source is effectively optimized, the problem of current instability caused by the crosstalk of the ground loop is reduced, and the PCB board area is effectively reduced to achieve The purpose of reducing costs.

Description

technical field [0001] The invention relates to the technical field of electrical power supplies, in particular to a control circuit for reducing output voltage ripple, a driving power supply and a television. Background technique [0002] With the rapid development of science and technology, the development of TV is also advancing by leaps and bounds, and consumers' requirements for TV picture quality are becoming more and more stringent. In order to meet the needs of consumers, TV manufacturers are also constantly making technological breakthroughs. At present, TVs with HDR functions can bring a strong visual shock in terms of color gamut, contrast, and depth of field, and consumers are full of praise. For LED TVs, to realize the perfect HDR function, the backlight partition of the module (that is, the Localdimming function) is indispensable, and the design of the backlight partition of the module can play the role of icing on the cake. [0003] At present, the most widel...

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Problems solved by technology

[0004] further as figure 2 As shown, the overall structure of IW7027 and IW7038 is similar. IW7038 integrates the switch MOSFET tube at the negative end of the backlight bar into the chip, and the working process is the same as that of IW7027. Both structures use a relatively independent DC to DC boost circuit. In practical applications, due to the high power, there is crosstalk between the ground loop of the DC-DC boost circuit and the ground loop of the IW7027 / 7038, causing the current of the backlight LED to be unstable, resulting in problems such as screen flicker or water ripple interference.

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