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LED protection circuit with overheat current reduction and constant current functions and driver

A technology for protecting circuits and currents, which is applied in the field of LED protection circuits, and can solve problems such as constant changes, LED lights flickering, etc.

Pending Publication Date: 2021-11-02
普诚创智(成都)科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is that in the prior art, after the current foldback circuit is added to the LED driver, the LED current will keep changing in the foldback interval, and the LED light will flicker. The LED protection circuit with constant current function solves the technical problem that the LED current will keep changing in the foldback interval after the current foldback circuit is added to the LED driver in the prior art, and the LED light will flicker.

Method used

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  • LED protection circuit with overheat current reduction and constant current functions and driver
  • LED protection circuit with overheat current reduction and constant current functions and driver
  • LED protection circuit with overheat current reduction and constant current functions and driver

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Embodiment 1

[0021] Please refer to figure 1 and figure 2 , the embodiment of the present invention provides an LED protection circuit with overheating current reduction and constant current functions, including a first operational amplifier circuit OP1, a third operational amplifier circuit OP3 and a field effect transistor Q1, and the third operational amplifier circuit OP3 has Two voltage input terminals are respectively used to input the variable voltage Viadj2 and the reference voltage Vref. The first operational amplifier circuit OP1 has two voltage input terminals, and its inverting input terminal and non-inverting input terminal are respectively used to input the normal voltage of the LED light. Working setting voltage Viadj and constant current threshold voltage Vtempa, the third operational amplifier circuit OP3 is used to convert the voltage signal into a current signal, the current output terminal of the third operational amplifier circuit OP3 passes through the resistor R2, t...

Embodiment 2

[0031] Please refer to Figure 1 to Figure 6 , an embodiment of the present invention provides an LED driver, including the LED protection circuit with overheating current reduction and constant current functions, the driver includes a driver chip, and the driver chip includes IADJ2 pins, VREF pins, IADJ pins , TEMPA pin and TEMPB pin, the change voltage Viadj2 and the reference voltage Vref input end of the third operational amplifier circuit OP3 are respectively connected to the IADJ2 pin and the VREF pin, the voltage Viadj and the constant voltage of the first operational amplifier circuit OP1 The input end of the current threshold voltage Vtempa is connected to the IADJ pin and the TEMPA pin respectively.

[0032] The driver chip can be a PT16751 chip. As a specific implementation, the IADJ2 pin is used to connect to a voltage divider circuit including a thermistor to obtain a temperature signal of the LED lamp board. As a specific implementation, the TEMPA pin is used to...

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PUM

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Abstract

The invention discloses an LED protection circuit and driver with overheating current reduction and constant current functions, the protection circuit comprises a first operational amplifier circuit OP1, a third operational amplifier circuit OP3 and a field effect transistor, and two voltage input ends of the OP3 are used for inputting variable voltage and reference voltage; two voltage input ends of the OP1 are used for inputting voltage Viadj and constant current threshold voltage, the current output end of the OP3 is connected with the current input end thereof through a resistor R2 and a resistor R3, the current output end of the OP3 is connected with the power supply end of the OP1 through a resistor R2 and a resistor R1, the current output end of the OP3 is grounded, the power supply end of the OP1 is connected with a power supply, the voltage Viadj input end of the OP1 is connected with the current input end of the third operational amplifier, the drain electrode of the field effect transistor is connected with the power supply, the source electrode is connected with the current input end of the OP3, and the grid electrode is connected with the output end of the OP1. A constant current function is added, and the reduced lamp current can be kept constant.

Description

technical field [0001] The invention relates to the technical field of LED lamps, in particular to an LED protection circuit with functions of overheating current reduction and constant current. Background technique [0002] Like most IC drivers, conventional LED drivers only have a thermal shutdown function. When the junction temperature of the driver exceeds the set temperature, the controller turns off the driver output and the LED light goes out. In order to solve the problem of LED lamp extinguishing under high temperature, a few LED drivers have added a current foldback circuit. When the junction temperature of the driver reaches the set temperature, the output of the driver reduces the LED current to reduce the heat generation of the LED lamp. The advantage of this design is that it can prevent the LED lamp from going out, so that the LED lamp can continue to work under low current conditions. However, after the LED current decreases, the brightness of the LED lamp...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H05B45/50H05B45/56H05B45/345
CPCH05B45/50H05B45/56H05B45/345Y02B20/30
Inventor 钟志远杨建宇
Owner 普诚创智(成都)科技有限公司