A temperature compensation circuit for linearly driving LEDs

Abstract

The invention relates to electronic circuit technology, in particular to designing a temperature compensation circuit for linearly driving LEDs. The circuit of the present invention is characterized in that it also includes an operational amplifier, a drive tube MN and a resistor R; wherein, the temperature sampling module samples the temperature of the LED module, and its output terminal is connected to the input terminal of the temperature compensation module; the temperature compensation module and the reference voltage module After the output voltage is added, it is connected to the positive input terminal of the operational amplifier; the negative input terminal of the operational amplifier is connected to the source of the drive tube MN, its enabling terminal EN is connected to the over-temperature shutdown module, and its output terminal is connected to the gate of the enabling tube MN pole; the positive pole of the LED module is connected to the power supply VDD, and its negative pole is connected to the drain of the switching tube MN; the source of the switching tube MN passes through R and then grounded to GND. The beneficial effect of the present invention is that the LED current can be adaptively reduced when the temperature rises, and the circuit can be directly shut down after the set temperature is exceeded, thereby realizing dual temperature protection of the LED. The invention is especially suitable for temperature compensation circuits driven by LEDs.

Description

technical field [0001] The invention relates to electronic circuit technology, in particular to designing a temperature compensation circuit for linearly driving LEDs. Background technique [0002] At present, in the field of electric LED driving circuit design, LED driving methods include linear driving and switching power supply driving. The linear drive method has the advantages of simple structure, low electromagnetic interference EMI, and low cost. There are many linear drive applications on the market. As a new type of light source, LED has the problem of heat dissipation. LEDs undergo recoverable device characteristic changes under high temperature conditions, but permanent decay will occur over time. When the working current is constant, the temperature rises, and the output light intensity decays quickly. Therefore, for a driver that drives an LED with a constant current, a driver with temperature compensation can well protect the lifetime and characteristics of ...

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Problems solved by technology

[0003] Now, the temperature protection circuit mainly uses the over-temperature shutdown module. On the one hand, this technology is prone to non-stop heating and thermal shutdown. On the other hand, the temperature in this technical solution generally refers to the internal temperature of the driver chip, which is different from There is a certain difference in the temperature of the LED, so it cannot be turned off in time and accurately, which will cause damage to the life of the LED and other performances.

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