Current equalizing system for controlling each branch current of LED (light emitting diode) lamp circuit

Abstract

The invention relates to the field of LED (light emitting diode) lamp circuit current equalizing technology, and particularly relates to a current equalizing system for controlling each branch current of an LED lamp circuit. Each LED lamp branch is provided with a corresponding constant-current control chip; each constant-current control chip comprises a first unit for generating reference current and a second unit for controlling the current of LED lamp branches; a control output end of the first unit is connected with a control input end of the second unit so that the first unit controls the current of the LED lamp branches through the second unit according to the reference current generated by the first unit; and the first units of all constant-current control chips from the first one to the last one are sequentially connected in series. The system provided by the invention can realize equal high-precision current among multiple constant-current control chips, and the difference of the resistors and tubes of different constant-current control chips does not influence the current of each LED lamp branch; and the expandability is high.

Description

technical field [0001] The invention relates to the technical field of LED lamp circuit current sharing, in particular to a current sharing system for controlling the current of each branch of the LED lamp circuit. Background technique [0002] The V-I (voltage-current) characteristic curve of an LED (light-emitting diode) lamp is similar to the V-I characteristic curve of a diode. The current changes according to the voltage index, and the voltage changes a little, and the current changes greatly. In the LED lamp circuit, all LED lamps are connected in series, and the current must be equal, but a higher power supply voltage is required. Therefore, when more LED lamps are needed, the LED lamps in the LED lamp circuit are usually connected in series first and then in parallel. However, when the branches of this LED lamp circuit are connected in parallel, due to the inevitable differences among the LED lamps, it is generally necessary to use a current sharing system to control...

AI Technical Summary

Problems solved by technology

[0003] At present, the current sharing systems used to control the current of each branch of the LED lamp circuit mainly include the following types: 1. figure 1 As shown, the single-chip multi-channel current sharing system, however, the single-chip multi-channel current sharing system has disadvantages such as inconvenient expansion, and when the number of branches of the required LED lights is not an integer multiple of the number of chip channels, some channels must be wasted ; 2, such as figure 2 As shown, in the fixed constant current system, each branch of the LED lamp circuit relies on the constant current chip to achieve constant current. Commonly used constant current chips include constant current diodes and other constant current ICs. However, this fixed constant current system is not uniform in nature. Current system, because the current consistency between multiple constant current chips also depends on the difference between constant current chips, that is, the difference in components such as resistance between constant current chips will affect the current consistency of each branch; 3. There are several types of constant current systems with variable current: such as image 3 As shown, the constant current scheme 1 adjusted through the digital communication interface; Figure 4 As shown, the constant current scheme 2 adjusted through the digital communication interface; Figure 5 As shown, the constant current scheme 3 adjusted by PWM mode; these systems are the same as the above-mentioned fixed constant current system, and each branch relies on the constant current chip to achieve constant current. It is not a current sharing system in essence, but an interface circuit is added to realize current regulation. , Therefore, the current consistency between multiple constant current chips in this constant current system adjusted by digital communication interface or by PWM mode also depends on the difference between constant current chips, that is, the constant current chip Differences in components such as resistors between them will affect the current consistency of each branch

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