Linear full-voltage frequency conversion constant current circuit and LED lamp equipped with same

Abstract

The invention provides a linear full-voltage frequency conversion constant current circuit and an LED lamp equipped with the same. The linear full-voltage frequency conversion constant current circuitcomprises a rectifying circuit, a load assembly, and a first switch constant current tube IC1 and a second switch constant current tube IC2 which are symmetrically arranged, wherein at least one loadis connected with the output end of the rectifying circuit; the S end of the first switch constant current tube IC1 and the S end of the second switch constant current tube IC2 are connected to the input end of the load assembly; the D end of the first switch constant current tube IC1 is connected to the output end of the rectifying circuit through a charging-discharging capacitor C1; and the D end of the second switch constant current tube IC2 is connected to the output end of the rectifying circuit. By adoption of the two switching constant current tubes, and by controlling the capacitor toperform charging-discharging switching according to the alternating current voltage changes, the automatic frequency conversion and constant current functions are realized in the condition of a 90-300V alternating current full voltage; and in the charging-discharging switch process through the charging-discharging capacitor, the load assembly can work in a switching linear constant current state,thereby greatly improving circuit efficiency and the input power factor.

Description

technical field [0001] The invention relates to the field of output control circuits of AC power sources, in particular to a linear full voltage frequency conversion constant current circuit and an LED lamp with the same. Background technique [0002] As an efficient new light source, LED is widely used in lighting in various fields due to its long life, low energy consumption, energy saving and environmental protection. The method of using single-chip microcomputer and embedded software to control the brightness of LED lamps through PWM and constant current drive chips has also been gradually promoted. However, since the operating frequency of the single-chip microcomputer is generally limited, the PWM frequency and dimming accuracy used are limited by the operating frequency of the single-chip microcomputer, that is, the PWM frequency multiplied by the dimming accuracy must be less than or equal to the operating frequency of the single-chip microcomputer. Therefore, the e...

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Problems solved by technology

However, since the operating frequency of the single-chip microcomputer is generally limited, the PWM frequency and dimming accuracy used are limited by the operating frequency of the single-chip microcomputer, that is, the PWM frequency multiplied by the dimming accuracy must be less than or equal to the operating frequency of the single-chip microcomputer

Therefore, the existing systems that use single-chip microcomputers to control the brightness of LED lamps through PWM and constant current drive chips have the following deficiencies. First, there is stroboscopic flicker when the lamps are high-brightness, which can be detected by the naked eye and will leave obvious bright spots on digital imaging equipment. Dark interlaced stripes; secondly, due to insufficient precision in low brightness changes, there will be perceivable brightness fluctuations, which will affect the brightness adjustment effect

That is to say, the method of using single-chip microcomputer and embedded software to adjust the frequency of lamps and lanterns is costly and poor in effect, and the use of linear constant current drive power supply is cost-effective, but it cannot realize the globalization of 110-220VAC wide voltage like switching power supply, and urgently needs to be improved.

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