Low power consumption constant current and backlight control circuit and TV

Abstract

The invention discloses a low-power-consumption constant current and backlight control circuit. The low-power-consumption constant current and backlight control circuit comprises a front-end power source circuit and a rear-end linear constant current circuit, wherein the front-end power source circuit comprises a power supply circuit and a feedback adjustment circuit, the rear-end linear constant current circuit is provided with a connection reference signal input end to be connected with constant current reference voltage, and the rear-end linear constant current circuit and an LED light string are connected / disconnected according to the magnitude of the constant reference voltage. A voltage collecting output end is led out of the connecting position of the rear-end linear constant current circuit and the LED light string through a voltage detection circuit to collect the voltage of the connecting position, and the voltage value of a control signal input end is adjusted according to the collecting result. The voltage detection circuit is used for connecting the voltage collecting output end and the connecting position when detecting that the rear-end linear constant current circuit is connected with the LED light string and disconnecting the voltage collecting output end and the connecting position when detecting that the rear-end linear constant current output end and the LED light string are disconnected.

Description

technical field [0001] The invention relates to the technical field of power supply control, in particular to a low power consumption constant current and backlight control circuit and a television set with the low power consumption constant current and backlight control circuit. Background technique [0002] The linear constant current modulation circuit is a unit circuit widely used in analog integrated circuits, and has a wide range of applications in practice. Among them, in the field of power control technology of LED TVs, the front-end circuit is often used to output a constant voltage, and the back-end circuit is used to realize step-up or step-down constant current to realize power supply to the main board of the TV set and the LED backlight. [0003] In the process of integrating TV components, TV motherboards and backlight strips usually need to be produced together, and different numbers of backlight LED strips will require linear constant current modulation circu...

AI Technical Summary

Problems solved by technology

When the linear constant current circuit works, the voltage at both ends of the switching tube will be due to the voltage error of the LED light string (generally, the range of a single LED is 2.8 to 3.4, due to the series connection of multiple LED lights, the difference between the upper limit and the lower limit of the voltage range of the LED light string will be relatively large), due to the influence of the intermodulation of the transformer (the general range is 7%), the higher the voltage, the greater the power consumption, which will cause the cost of the device to increase and the circuit efficiency to decrease

In addition, in order to reduce the temperature of the switching tube, the general switching tube will be used in parallel with multiple mos tubes or triodes, which leads to an increase in cost

[0006] In addition, when the existing technology improves the linear constant current circuit, when the power of the backlight LED is turned off, one end of the backlight LED is still connected to a useful electrical device and there is a weak current, so that the weak current is reversely connected to the backlight LED to make the backlight The LED turns on and emits a weak light, which is not allowed in the technical field of TV manufacturing

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