Chip over-temperature protection circuit applied to alternative current LED drive system

Abstract

The invention discloses a chip over-temperature protection circuit applied to an alternative current LED drive system. The chip over-temperature protection circuit comprises a temperature sensing diode, a temperature setting module, a oblique wave voltage module, a reference voltage generating module and a constant-current control module. In the time of work, when the temperature setting module and the oblique wave voltage module detect the temperature of a chip to be larger than a protection temperature through the temperature sensing diode, the temperature setting module and the oblique wave voltage module generate corresponding signals, the signals are chosen and combined through an adder and reference voltage generated by the reference voltage generating module and then input to the constant-current control module. The constant-current control module controls a current flowing through an LED in a lamp to be reduced, the temperature of the chip can be reduced, and therefore negative feedback exists between the temperature of the chip and the current. If the lamp does not dissipate heat well, when the current is reduced to reach a certain value, a heating amount of the chip is equal to a heat dissipation amount, balance is achieved, therefore the lamp is prevented from being turned off, and the problem of circulating turn-on and turn-off is avoided and stability of the system is not affected.

Description

technical field [0001] The invention relates to the technical field of LED drive systems, in particular to a chip over-temperature protection circuit applied in an AC LED drive system. Background technique [0002] LED (Light Emitting Diode, Light Emitting Diode) is a new generation of light source that uses semiconductor materials as the electro-optical conversion medium. It has the characteristics of energy saving, environmental protection, long life and small size. It will soon replace energy-saving lamps and become the mainstream lighting. With the implementation of the global ban on production and sales of incandescent lamps, LED lighting will face the opportunity to replace incandescent lamps, with a market size of hundreds of billions. [0003] In the existing AC LED drive system used in LED lighting fixtures, when the chip (the LED chip of the LED in the lamp) heats up and the temperature is too high, the over-temperature protection method is generally to directly tu...

AI Technical Summary

Problems solved by technology

However, if the heat dissipation is not good, this protection method may have the problem of switch cycle work (turn off after the temperature is high, turn on after the temperature drops after turning off), the system is unstable, causing the lights to flicker

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