A single feedback direct push type DC dimming led lamp drive circuit

Abstract

The invention discloses a single-feedback direct push type DC dimming LED lamp tube drive circuit, which includes an AC-DC conversion circuit, a power supply circuit driven by the LED lamp tube, an AC-DC conversion circuit output voltage control circuit, and an AC-DC conversion circuit Internal Vcc" power-down suppression circuit, PWM to DC dimming control circuit, LED lamp current control circuit and single feedback LED lamp; the AC-DC conversion circuit of the present invention adopts a single output design, and the output AC-DC conversion circuit is single The group output voltage value is a variable voltage that is directly supplied to the single feedback LED lamp tube to work, without a large amount of high-frequency EMI radiation noise of the Boost boost circuit. The invention effectively reduces the standby power consumption of liquid crystal display products, and is more energy-saving and environmentally friendly. The invented drive circuit has low cost, high efficiency, low standby power consumption and lower EMI radiation characteristics.

Description

technical field [0001] The invention relates to a single feedback direct push type DC dimming LED lamp tube driving circuit. Background technique [0002] The traditional liquid crystal display product LED lamp circuit principle is as follows: figure 1 As shown, the commercial AC 90V-264V generates a low-voltage DC after voltage conversion by the AC-DC conversion circuit, such as: 19V DC, and the 19V DC is boosted by the Boost circuit to generate the working voltage required by an LED lamp. For example: 25V-70V direct current is used for LED lamps, the Boost booster circuit is driven by the booster circuit control chip, and the output feedback terminals of each light string in the LED lamp tube are electrically connected to the feedback pins of the booster circuit control chip. Connection, the boost circuit control chip controls the current of each light string in the LED lamp tube when it is working, so as to control the average brightness of the liquid crystal display scr...

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Problems solved by technology

[0003] However, the above-mentioned prior art has the following problems: 1. The cost and price of the parts and materials of the LED lamp tube drive power supply board are relatively high, and the market competitiveness has begun to be lacking in terms of price.

2. The conversion efficiency of the LED lamp drive circuit (excluding the conversion efficiency of the AC-DC conversion circuit) is between 85% and 90%, and the conversion efficiency is not high. When designing EPA7.0 new energy-efficient LCD products, it is often necessary to further Only by improving the power conversion efficiency of the AC-DC conversion circuit can it meet the requirements of the EPA7.0 new energy efficiency regulations, and when the power conversion efficiency of the AC-DC conversion circuit is improved, the cost and price of the parts and materials of the LED lamp drive power board will be further increased

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