LED (Light Emitting Diode) driving circuit

Abstract

The invention discloses an LED (Light Emitting Diode) driving circuit, which comprises a direct-current (DC) input power supply and at least one branch. The branch is connected between the positive terminal and the negative terminal of the DC input power supply and comprises a plurality of LED groups, bypass circuits and a constant-current source circuit, wherein each LED group is formed by connecting at least one LED in series, the bypass circuits correspond to the LED groups, input terminals of the bypass circuits are connected with positive poles of the LED groups, output terminals of the bypass circuits are connected with negative poles of the LED groups, a single LED group and a single bypass circuit corresponding to the single LED group form a unit link, a unit link group is formed after a plurality of unit links are connected in series, the unit link group is connected between the positive terminal of the DC input power supply and the input terminal of the constant-current source circuit in a series, the output terminal of the constant-current source circuit is connected with the negative terminal of the DC input power supply, and a control terminal of the bypass circuits is connected with a driving terminal of the constant-current source circuit. The LED driving circuit has the advantages of little linear loss, very high reliability, very simple circuit structure, small size, and capability of being formed through partial or all integration.

Description

technical field [0001] The invention relates to the field of LED general lighting, in particular to an LED driving circuit. Background technique [0002] As a new type of light source, LED has significant advantages such as high luminous efficiency and long life. Since the LED is a current-mode device, the current flowing through the LED must be controlled during use, and it is usually driven by a constant current mode. In addition, the driving circuit should also have the advantages of high efficiency, low cost, small size, and a service life comparable to that of the LED. [0003] The simplest LED driver circuit such as figure 1 As shown, usually multiple LEDs are connected in series with a current limiting resistor, and then connected to a DC power supply or a DC power supply after the AC power supply has been rectified and filtered. The constant current effect of this circuit is very poor, and the loss of the current limiting resistor is also large. [0004] More, it ...

AI Technical Summary

Problems solved by technology

The invention simplifies the circuit design and reduces a certain power loss by grouping LED light strings, setting different numbers of LEDs in each group, and controlling the current on and off of each group of LED light strings through parallel switches. The switch of the string is controlled by the control switch, and modules such as addition and subtraction counters, voltage comparators, and logic selection circuits are also used, and the structure is still very complicated.

Similarly, when a certain control switch Ki is turned on and off in this invention, the change of the voltage at the control switch terminal will be applied to the constant current source, which increases the power loss of the circuit

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