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LED constant-current source and control method thereof

A technology of constant current source and power supply, applied in the field of light emitting diode (LED) constant current source and its control, can solve the problems of high-voltage MOS tube heating and low efficiency, avoid excessive heating, improve utilization, solve no-load and The effect of the short circuit problem

Active Publication Date: 2014-07-09
QX MICRO DEVICES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The disadvantage of the traditional technology is that the chip obtains the constant current effect by changing the on-resistance of the high-voltage MOS tube. If the voltage difference between the rectified and filtered voltage and the voltage of the load LEDs is large, the loss on the voltage difference will be applied to the high-voltage MOS. On the tube, so that the efficiency is not high, and the high-voltage MOS tube will heat up more seriously

Method used

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  • LED constant-current source and control method thereof
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  • LED constant-current source and control method thereof

Examples

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no. 1 example

[0042] pass Figure 4 It can be known from the circuit in that the current flowing through the output capacitor C1 and the load LEDs will flow through the sampling resistor Rcs; by integrating the voltage on the sampling resistor Rcs, the integral comparison level is a reference level V REF (the value of the reference level VREF in the figure), the integral resistor R3, and the integral capacitor C2. Therefore, when the voltage on the sampling resistor Rcs is relatively high, its sampling voltage is the same as the reference level V REF The difference value discharges the capacitor C2 through the resistor R2; when the voltage on the sampling resistor Rcs is relatively low, its sampling voltage is the same as the reference level V REF The difference is charged to the capacitor C2 through the resistor R2.

[0043] When the average voltage on the sampling resistor Rcs and the reference reference voltage V REF When consistent, the system is in a stable state; when stable, the l...

no. 2 example

[0051] It can be seen from the figure that the voltage on the output capacitor C1 gradually rises after power-on, and at this time there is no current on the load LEDs or the current does not reach the set value until the voltage on the output capacitor C1 makes the current on the load LEDs reach After setting the value, the voltage on the output capacitor C1 tends to be stable.

[0052] When the AC input rectified half-wave voltage is less than the voltage on the output capacitor, the voltage drop on the resistor R2 is the AC AC input rectified half-wave voltage signal, and the voltage drop on R1 is close to zero, the output terminal of the third operational amplifier Buffer The generated source current I1 is amplified to follow the current I2 by mirroring multiples, so that the negative input terminal of the second comparator CPA is zero to the floating ground potential, so the switch Q1 is turned on.

[0053] When the AC input rectified half-wave voltage is greater than the...

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Abstract

The invention relates to an LED constant-current source and a control method of the LED constant-current source. The constant-current source comprises a rectifier module, a sampling resistor (Rcs), a switch (Q1) and an output capacitor (C1), wherein the sampling resistor (Rcs) and the switch (Q1) are connected to an output circuit of the rectifier module in series, and the output capacitor (C1) is connected with loads (LEDs) in parallel. The sampling resistor is electrically connected with an average current detection control module. The control end of the switch is electrically connected with a voltage detection and switch drive module. The average current detection control module comprises a first operational amplifier, the negative input end of the first operational amplifier is sequentially and electrically connected with an integral resistor (R3) and the high-voltage connecting end of the sampling resistor, and the positive input end of the first operational amplifier is connected with the VREF, wherein an integrating capacitor (C2) is connected between the output end and the negative input end in a bridging mode. The voltage detection and switch drive module comprises a second comparator, the positive input end of the second comparator is electrically connected with the output end of the first operational amplifier, the negative input end of the second comparator is electrically connected with the positive output end of the rectifier module, and the output end is electrically connected with the control end of the switch.

Description

technical field [0001] The invention relates to an electronic circuit and signal processing technology, in particular to a light-emitting diode (LED) constant current source and a control method thereof. Background technique [0002] With the popularization and application of LED driving power, LED has also experienced multi-level development. In addition to LED point light sources, LED surface light sources and HV-LEDs are gradually favored by the market. At present, most of the LED driving power supplies on the market are switching power supplies. Although the constant current driving effect is better, the cost of the switching power supply is relatively high, especially the cost of the inductor; so there are similar constant current diodes (CRD) Simple application, it is used in LED power modules with low current and low power, the cost is very low, and there is no inductance. [0003] Traditional CRD constant current control system, the circuit structure is as follows ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H05B37/02
Inventor 李剑黄朝刚黎海明吴玉强李伟华
Owner QX MICRO DEVICES