LED linear constant current circuit with overvoltage detection function and overvoltage detection method

Abstract

The invention discloses an LED linear constant current circuit with an overvoltage detection function. The LED linear constant current circuit comprises at least one LED lamp, a feedback loop and an overvoltage protection circuit, the feedback loop is connected with the LED lamp, and the overvoltage protection circuit is connected with the LED lamp through the feedback loop and used for conductingovervoltage detection on the working voltage of the LED lamp. The invention further discloses an LED lamp overvoltage detection method. According to the invention, a traditional switching power supply, an operational amplifier and a BJT circuit are abandoned, and the use of EMI / switching voltage spikes / special switching power supply chips / high-frequency transformers and other chips is reduced, sothat the hardware cost in the design process is reduced; negative feedback linear LED constant currents of double triodes are adopted, single-chip microcomputer control port resources are abandoned,stable self-adjustment of LED lamp current is achieved, and the development cost is reduced; and a self-overvoltage protection circuit is adopted to control the working voltage of a negative feedbacklinear LED constant-current circuit of the double triodes, so that the overvoltage protection function of the LED lamp is realized.

Description

technical field [0001] The invention belongs to the technical field of LED constant current output circuits, and in particular relates to an LED linear constant current circuit with an overvoltage detection function and an overvoltage detection method. Background technique [0002] Household appliances, such as range hoods, steamers, ovens, etc., are often equipped with LED ambient lights on the display boards, and daily lighting is generally driven by a constant current power supply; the existing constant current circuit is generally based on a switching power supply LED constant current circuit, which is used in high-power occasions, has disadvantages such as poor EMI effect, prominent switching peak signal, and high circuit cost; there is also an LED constant current circuit based on operational amplifiers and transistors, which is used in low-power occasions , but its operating efficiency is low, less than 50%. [0003] Moreover, the main method of the matrix LED curren...

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Problems solved by technology

[0002] Household appliances, such as range hoods, steamers, ovens, etc., are often equipped with LED ambient lights on the display boards, and daily lighting is generally driven by a constant current power supply; the existing constant current circuit is generally based on a switching power supply LED constant current circuit, which is used in high-power occasions, has disadvantages such as poor EMI effect, prominent switching peak signal, and high circuit cost; there is also an LED constant current circuit based on operational amplifiers and transistors, which is used in low-power occasions , but its operating efficiency is low, less than 50%

[0003] Moreover, the main method of current balance control circuit for matrix LEDs on the market is generally: current control based on a dedicated LED constant current chip. This method is relatively simple in form and only needs one constant current chip; but the price of the dedicated chip Expensive, and in order to meet the functions of the chip, more peripheral circuits and unit machines are required, which leads to high hardware costs, too many detection ports, and the LED current is greatly affected by temperature

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