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Light emitting diode driving circuit

A technology of light-emitting diodes and driving circuits, which is applied in the layout of electric lamp circuits, light sources, electric light sources, etc., can solve the problem that the compensation capacitor voltage cannot be rapidly changed, the output voltage ripple cannot be effectively reduced, and the closed-circuit transfer function of the LED driving circuit cannot be Quickly transform and other problems to achieve the effect of reducing the effect and improving the phase boundary

Active Publication Date: 2012-10-31
HIMAX ANALOGIC INC
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, when using the PWM dimming method to adjust the brightness of the LED, ripples will be generated in the output voltage of the LED driving circuit, and the current flowing through the LED will also change according to the PWM dimming method. , and due to the change of the current flowing through the light-emitting diode and the generation of ripples, the closed-loop transfer function in the light-emitting diode driving circuit will be affected by the ripples and cannot be changed rapidly
Furthermore, since an error amplifier (error amplifier) ​​is usually included in the LED driving circuit, the closed-loop transfer function will also be affected by the slew rate of the error amplifier, so that the voltage of the compensation capacitor used to reduce the ripple generated unable to change quickly
As a result, the ripple in the output voltage cannot be effectively reduced, and the LED drive circuit cannot operate stably

Method used

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  • Light emitting diode driving circuit

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Embodiment Construction

[0016] figure 1 A schematic diagram of a light emitting diode driving circuit according to an embodiment of the present invention is shown. LED driving circuit 100 takes an input voltage V IN converted to an output voltage V OUT , for driving one or more connected light emitting diodes (LEDs) 102, wherein the LED driving circuit 100 can be fabricated in an integrated circuit (IC). The LED driving circuit 100 includes a control circuit 110 , a transistor switch 120 and a compensation circuit 130 . The control circuit 110 is used for receiving an oscillating signal OS to generate a pulse driving signal PS for use by the transistor switch 120 . The duty ratio of the transistor switch 120 will determine the input voltage V IN and output voltage V OUT The proportional relationship between them. When the pulse driving signal PS turns on the transistor switch 120, the input voltage V IN An inductor 104 located outside the LED driving circuit 100 and connected to the LED drivin...

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Abstract

The invention relates to a light emitting diode driving circuit, which comprises a control circuit, a transistor switch and a compensating circuit, wherein the control circuit receives an oscillator signal so as to generate a pulse drive signal; the transistor switch is turned on by the pulse drive signal so as to ensure that an inductor is charged by input voltage, wherein when the transistor switch is cut off, the inductor can transmit induced current to a light emitting diode; and the compensating circuit is coupled between the control circuit and an capacitor, wherein the capacitor is used for reducing ripples in the output voltage of the corresponding induced current; and when the compensating circuit is controlled by a light modulating control signal which controls the brightness ofthe light emitting diode, the compensating circuit is subjected to a charge and discharge process along the capacitor.

Description

technical field [0001] The present invention relates to a driving circuit, and in particular to a light emitting diode (LED) driving circuit. Background technique [0002] Generally speaking, a light-emitting diode (LED) driving circuit is used to convert an input voltage into a required output voltage to drive one or even a plurality of connected LEDs for display purposes. In addition, the brightness of the LED can be varied by adjusting the brightness of the LED driving circuit in a pulse width modulation (PWM) manner. [0003] However, when using the PWM dimming method to adjust the brightness of the LED, ripples will be generated in the output voltage of the LED driving circuit, and the current flowing through the LED will also change according to the PWM dimming method. , and due to the change of the current flowing through the LED and the generation of ripple, the closed-loop transfer function (closed-loop transfer function) in the LED driving circuit will be affected...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H05B37/02
Inventor 陈开基吴劲龙
Owner HIMAX ANALOGIC INC
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