Thermal foldback control circuit and control method of light-emitting diode (LED)
A technology of light-emitting diodes and control circuits, which is applied to the layout of electric lamp circuits, light sources, electric light sources, etc., can solve problems such as difficult heat dissipation and LED flickering, and achieve the effect of avoiding flickering
Active Publication Date: 2011-07-20
RICHTEK TECH
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The current design of LED lamps focuses on the safety and heat dissipation of the LED itself. Therefore, the LED and its driving circuit are set separately, and a space for air convection is specially reserved for the LED to reduce the temperature of its surface contact. Most of the driving circuits are set in In a confined space, heat dissipation is not easy. Therefore, sometimes the temperature of the controller chip of the driving circuit is higher than the temperature of the LED, and the OTP is touched to make the controller chip enter the thermal protection mode, causing the driving current of the LED to be cut off, and the LED flickers accordingly. The phenomenon
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[0018] The specific implementation manners of the present invention will be described in detail below in conjunction with the accompanying drawings. Apparently, the described embodiments are only part of the embodiments of the present invention, and other embodiments obtained by those skilled in the art without creative efforts all belong to the protection scope of the present invention.
[0019] figure 1 It is a schematic diagram according to an embodiment of the present invention, the LED array 10 is coupled to the power supply Vcc through a resistor R1, and the controller chip 12 is connected to the LED array 10 to control the driving current Iled of the LED array 10 . The controller chip 12 includes a BJT 14 connected in series with the LED array 10 , so the collector current Ic of the BJT 14 is equal to the driving current Iled of the LED array 10 . Driver 16 is connected to the base of BJT 14 to control the collector current Ic of BJT 14 . Like the prior art, the contr...
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The invention discloses a thermal foldback control circuit and a control method of a light-emitting diode (LED). The thermal foldback control circuit and the control method of the LED are used for sensing the temperature of the LED and the temperature of a control chip of the LED and gradually reducing a driving current of the LED before overheating of the LED or the control chip so as to avoid the twinkle of the LED caused by the startup of an overheating protecting mechanism due to the overheating of the control chip. The thermal foldback control circuit comprises an outside heat-sensing end for receiving an outside heat-sensing signal related to the temperature of the LED, a heat-controllable circuit for sensing the temperature of the control chip so as to determine an inside heat-sensing signal and a multi-path sensing circuit for connecting the outside heat-sensing end and the heat-controllable circuit and triggering a heat-regulating signal to regulate the driving current intelligently and further regulate the temperatures of the LED and the control chip automatically when the outside heat-sensing signal surpasses a first threshold signal or the inside heat-sensing signal surpasses a second threshold signal.
Description
technical field [0001] The invention relates to a light emitting diode (LED) controller, in particular to a thermal foldback (thermal foldback) control circuit and method of the LED. Background technique [0002] Over Temperature Protection (OTP) is a technology for protecting the controller chip, which shuts down the controller chip when the temperature of the controller chip rises to a set value, so as to avoid the controller chip from being burned. The thermal foldback technology is a mechanism to protect the LED. When the temperature of the LED rises to a set value, it reduces the driving current of the LED to prevent the temperature of the LED from continuing to rise. The current design of LED lamps focuses on the safety and heat dissipation of the LED itself. Therefore, the LED and its driving circuit are set separately, and a space for air convection is specially reserved for the LED to reduce the temperature of its surface contact. Most of the driving circuits are se...
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Inventor 黄培诚刘景萌
Owner RICHTEK TECH