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Overvoltage protection circuit in LED (Light Emitting Diode) driving power supply, and LED driving power supply

An overvoltage protection circuit and LED driving technology, which is applied to emergency protection circuit devices, electrical components, irreversible AC power input conversion to DC power output, etc., can solve problems such as unsuitable applications, and achieve small size and cost reduction. Effect

Active Publication Date: 2015-05-13
SHANGHAI BRIGHT POWER SEMICONDUCTOR CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, because the freewheeling time of the current in the rectifier diode is proportional to the peak current of the primary side, this application is not suitable for systems with varying peak currents.

Method used

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  • Overvoltage protection circuit in LED (Light Emitting Diode) driving power supply, and LED driving power supply
  • Overvoltage protection circuit in LED (Light Emitting Diode) driving power supply, and LED driving power supply
  • Overvoltage protection circuit in LED (Light Emitting Diode) driving power supply, and LED driving power supply

Examples

Experimental program
Comparison scheme
Effect test

no. 1 example

[0040] Such as figure 2 As shown in the figure, the figure shows the source-driven step-down Buck topology commonly used in LED drive power supplies, usually including: rectifier bridge 201, input capacitor 202, output capacitor 203, rectifier diode 205, inductor 204, power supply resistor 206, power supply capacitor 209 , switching power tube 207 , current sampling resistor 208 , source control tube 222 , output LED load 221 and control chip 210 . The overvoltage protection circuit of the control chip 210 of the present invention includes: a sampling and holding unit 213, a current source 212, a charging capacitor 211, a comparator unit 214, an overvoltage protection logic unit 215, a control logic unit 216, a demagnetization time detection unit 218 and drive unit 217 .

[0041]When the switching power transistor 207 is turned on, the current of the inductor 204 starts to rise linearly with time, and at this time, the voltage CS on the current sampling resistor 208 also ris...

no. 2 example

[0044] Such as Figure 4 As shown, the figure shows the buck topology of the gate drive commonly used in LED drive power supplies, usually including: a rectifier bridge 301, an input capacitor 302, an output capacitor 303, a rectifier diode 305, an inductor 304, a power supply resistor 306, and a power supply capacitor 309 , switching power tube 307 , current sampling resistor 308 , output LED load 321 and control chip 310 . The overvoltage protection circuit of the control chip 310 of the present invention includes: a sampling and holding unit 313, a current source 312, a charging capacitor 311, a comparator unit 314, an overvoltage protection logic unit 315, a control logic unit 316, a demagnetization time detection unit 318 and drive unit 317 .

[0045] The working principle of the second embodiment is basically the same as that of the first embodiment, the difference is that the second embodiment is a gate-driven step-down Buck topology, and the input terminal of the dema...

no. 3 example

[0047] Such as Figure 5 As shown, the diagram shows the flyback topology of the source drive of the two-winding scheme in the LED drive power supply. Usually includes: rectifier bridge 401, input capacitor 402, transformer 405, transformer primary winding 403, transformer secondary winding 404, chip power supply resistor 407, chip power supply capacitor 406, output freewheeling diode 408, output capacitor 409, LED load 310, Switching power tube 411 , source controller 412 , current sampling resistor 413 and control chip 420 . The overvoltage protection circuit of the control chip 420 of the present invention includes: a sampling and holding unit 423, a current source 422, a charging capacitor 421, a comparator unit 424, an overvoltage protection logic unit 425, a control logic unit 426, a demagnetization time detection unit 428 and drive unit 427 .

[0048] The working principle of the third embodiment is basically the same as that of the first embodiment, except that the t...

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PUM

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Abstract

The invention provides an overvoltage protection circuit in an LED (Light Emitting Diode) driving power supply. The overvoltage protection circuit is characterized by comprising a sampling and holding unit, a current source, a charging capacitor, a comparator unit, an overvoltage logic unit, a logic control unit and a demagnetized time detection unit, wherein the sampling and holding unit is used for detecting the voltage of the current sampling resistor of the LED driving power supply and generating a demagnetized reference time through the current source, the charging capacitor and the comparator unit; the demagnetized time detection unit is used for detecting the demagnetized time; the overvoltage logic unit is used for comparing the demagnetized time with the demagnetized reference time and outputting an overvoltage signal when the demagnetized time is smaller than or equal to the demagnetized reference time; and the logic control unit is used for judging whether the overvoltage is output and shutting off a power switch tube of the LED driving power supply.

Description

technical field [0001] The invention relates to an overvoltage protection circuit in an LED driving power supply, especially used in the scheme of the LED driving power supply without an auxiliary winding. Background technique [0002] The function of the LED drive power supply is to provide a constant output current of the LED lamp, but if the output LED is open circuit or other conditions that increase the output voltage occur, the LED drive power supply must take corresponding measures to keep the output voltage not exceeding the withstand voltage of the output capacitor, otherwise output capacitor will be destroyed. In the traditional LED drive power scheme, a separate transformer winding is generally used to detect the output voltage, and then divided by resistors, input to a separate pin of the chip to directly detect the output voltage, so as to determine whether the drive power has overvoltage. [0003] The traditional overvoltage protection scheme increases the siz...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/125H02M7/12
Inventor 孙顺根于得水
Owner SHANGHAI BRIGHT POWER SEMICONDUCTOR CO LTD