SI23077A - Circuit for temperature control of a led diode - Google Patents

Abstract

Subject of the invention is a circuit for temperature control of LED diodes depending on the environment temperature, where the analogue voltage signal is generated depending on the assessed temperature by the sensor circuit (1) while this signal is compared to a ramp frequency set internally on the controller (3) by way of a resistor (2) and regarding the crossing point between the ramp frequency and the generated analogue voltage signal, whereas the generated controller (3) signal determines the current whose magnitude directly depends on the width of the controller (3) signal generated depending on the assessed temperature by the sensor circuit (1).

Description

TEMPERATURE CONTROLLER LED DIODES

The subject of the invention is a circuit for temperature control of an LED, which makes it possible to change the brightness of the LED depending on the ambient temperature. The circuit described may also be used in controlling lighting, e.g. car headlights car fog lights. The invention belongs to the class F21V29 / 00 of the international patent classification

The technical problem that the circuit according to the invention successfully solves is the high dependence of the luminosity of the LED on the ambient temperature and the consequent increase or decrease. reducing the brightness of LEDs.

Solving the technical problem concerns the problem of heating, especially light bodies made using LEDs. In the case of luminaires with one or more LEDs, the problem of overheating must be solved either by means of suitable mechanical cooling systems or. the construction of enclosures of luminaries that effectively dissipate heat.

The circuit of the invention detects the temperature of the LED chip and controls the increase or decrease. reducing current through the LED. With the right combination

2o NTC and PTC resistors and associated elements for the proper operation of the circuit it is possible to produce such a control voltage curve that will properly generate current through the LED, depending on the temperature of the LED chip.

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I will explain the invention in more detail on the basis of an embodiment and accompanying drawings, of which:

Figure 1 is a block diagram of a circuit of the invention;

Figure 2 shows the curve of the luminosity dependence on the temperature of the LED; Figure 3 design of the control circuit.

According to the invention, the problem is solved by a circuit for temperature control of the LED io diode, which generates an analog voltage signal depending on the detected temperature on the sensor circuit 1, consisting of NTC and PTC resistor. This signal is compared to the ramp frequency previously set internally on the controller 3. Given the intersection point between the ramp frequency and the generated analog voltage signal, a corresponding regulator signal 3 is generated at the output terminal from controller 3, which opens the FET transistor and opens at the appropriate width a diode gate through which current flows, the magnitude of which directly depends on the signal width of the controller 3, which is generated depending on the temperature sensed on the sensor circuit 1.

Figure 2 shows curves that illustrate the conditions on the NTC and PTC 20 resistors and the voltage and current curve through the LED and thus the dependence of the LED brightness on the temperature.

The circuit according to the invention operates over the entire temperature range between -40 ° and 105 °. In order for the circuit according to the invention to function properly, it is necessary to provide adequate cooling by means of a refrigerator, which can be mounted on the underside under the LED.

Claims (1)

PATENT APPLICATION 1. A temperature control circuit of an LED, characterized in that 5 that the analog voltage signal is generated depending on the sensed temperature on the sensor circuit (1), comparing this signal with a ramp frequency internally set on the controller (3) by means of a resistor (2) and with respect to the intersection point between the ramp frequency and analog voltage signal generated by the signal io of the controller (3) determines the current whose size depends directly on the width of the signal of the controller (3), which is generated depending on the sensed temperature on the sensor circuit (1).