Constant current source control circuit

Abstract

The present invention discloses a constant-current source control circuit which comprises a main circuit, a reference condenser circuit, a voltage control current source circuit and a switch tube control circuit. The invention is characterized in that the main circuit is a power conversion circuit which comprises an inductor L1, an inductive current detecting resistor SR1 and a first switch tube SQ1. The reference capacitor circuit comprises a reference capacitor SC3 and a second switch tube SQ3. The voltage control current source circuit is used for charging the reference capacitor SC3 and has a current magnitude which is proportional with the output voltage U0. The switch tube control module synchronously controls the switching of the first switch tube SQ1 and the second switch tube SQ3, and controls the product of output voltage U0 and the switching time toff of switch tube to a constant number. The constant-current source control circuit of the invention has the advantages of simple structure, low cost, high efficiency, etc.

Description

technical field [0001] The invention relates to a control circuit of a constant current source. More specifically, the present invention relates to a control and drive circuit for a constant current source for driving LEDs. Background technique [0002] With the development and maturity of high-power LED technology, the performance index of LED for lighting has been greatly improved day by day. At present, the luminous efficiency of industrialized white LEDs has reached (70-90) lm / W, far exceeding the luminous efficiency level of ordinary incandescent lamps. High-power LEDs will be more and more widely used in the field of lighting. It is the fourth-generation lighting source that replaces fluorescent lamps and incandescent lamps in the 21st century. [0003] Since the LED lamp has a large voltage variation range according to the number of LEDs, and the driving current of the LED can only obtain high light efficiency and long life if the driving current is constant, so the...

AI Technical Summary

Problems solved by technology

[0004] The existing constant current power conversion circuit has low efficiency, complex circuit, not easy to control, and limited range of application, etc., which affect its use

In the existing technology, such as figure 1 Shown is a constant current device (US.Patent NO.6954058B2, On OCt, 11, 2005), the circuit is complicated, difficult to realize, and high in cost

like figure 2 The converter shown as feedback voltage and reference output voltage (US.Patent NO.7317302B1, On Jan, 8, 2008) is a constant voltage output, which limits its application range

[0005] For the Buck converter with floating output, its general constant current control method needs to obtain a constant output current by sampling the output current, and it is necessary to add an isolation amplifier circuit such as an optocoupler to amplify the current signal, which will increase the cost and circuit complexity, reduces reliability

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