Low power consumption constant current and backlight control circuit and TV

Abstract

The invention discloses a constant current and backlight control circuit with low power consumption, which includes a front-end power supply circuit and a rear-end linear constant-current circuit; the front-end power supply circuit includes a power supply circuit and a feedback adjustment circuit; the rear-end linear constant-current circuit is provided with a connection reference The signal input terminal is connected to the constant current reference voltage, and the connection between the back-end linear constant current circuit and the LED lamp string to be powered is turned on / off according to the size of the constant current reference voltage; the back-end linear constant current circuit A voltage detection circuit is used to lead out a voltage acquisition output terminal at the connection with the LED light string to be powered to collect the voltage at the connection, and adjust the voltage value of the control signal input terminal according to the collection result.

Description

Technical field [0001] The present invention relates to the technical field of power supply control, in particular to a low-power constant current and backlight control circuit and a television with the low-power 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 for LED TVs, the front-end circuit is often used to output a constant voltage, and the back-end circuit is used to achieve a boost or step-down constant current to achieve power supply to the TV motherboard and 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 circuits to adapt to output different voltage...

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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