Temperature compensated LED lighting application circuit

Abstract

This utility model relates to the field of temperature compensation technology and discloses a temperature-compensated LED lighting application circuit with stable light source, including a temperature detection circuit (120) for acquiring the temperature signal generated when the LED beads are working, a main control module (MCU) and a graded dimming circuit (130). The main control module (MCU) is used to receive the temperature signal and output a PWM signal according to the temperature signal; the graded dimming circuit (130) is used to receive the PWM signal; the main control module (MCU) adjusts the duty cycle of the output PWM signal according to the feedback temperature signal to control the graded dimming circuit (130) to dim the LED beads.

Description

Technical Field

[0001] This utility model relates to the field of temperature compensation technology, and more specifically, to a temperature-compensated LED lighting application circuit. Background Technology

[0002] LEDs are widely used in electronics, such as architectural lighting, automotive headlights and taillights, backlighting for LCD displays in personal computers and high-definition TVs, and flashlights. However, LED modules also generate heat during operation, causing the temperature of the LED beads to increase. As the LED bead temperature rises, the brightness decreases or fluctuates. Since the voltage is fixed, the heated LED beads cause an increase in current, which may damage or shorten the LED's lifespan.

[0003] Therefore, ensuring the lighting quality and lifespan of LED light sources has become a technical problem that urgently needs to be solved by those skilled in the art. Utility Model Content

[0004] The technical problem to be solved by this utility model is to address the shortcomings of the existing technology where the brightness of LED beads decreases or fluctuates after the temperature rises, and since the voltage is fixed, the heated LED beads cause the current to rise, which may damage or shorten the life of the LED. This invention provides a temperature-compensated LED lighting application circuit with stable light source.

[0005] The technical solution adopted by this utility model to solve its technical problem is: to construct a temperature-compensated LED lighting application circuit, which has the following features:

[0006] A temperature detection circuit is configured on the adjacent side of the LED bead and close to the LED bead to acquire the temperature signal generated when the LED bead is working.

[0007] The main control module has its input terminal coupled to the output terminal of the temperature detection circuit, and is used to receive the temperature signal and output a PWM signal according to the temperature signal.

[0008] A graded dimming circuit, one end of which is connected to one end of the LED lamp bead, and the other end is coupled to the pulse signal output terminal of the main control module, for receiving the PWM signal;

[0009] The main control module adjusts the duty cycle of the output PWM signal according to the feedback temperature signal to control the graded dimming circuit to dim the LED beads.

[0010] In some embodiments, the temperature detection circuit includes at least a thermistor and a sixth capacitor.

[0011] The thermistor is attached to the LED chip and is used to acquire the temperature signal generated when the LED chip is working.

[0012] One end of the thermistor and one end of the sixth capacitor are connected to the temperature signal terminal of the main control module to receive the temperature signal.

[0013] In some embodiments, the graded dimming circuit includes at least a MOSFET and a fourth resistor.

[0014] The gate of the MOS transistor is connected to one end of the fourth resistor.

[0015] The other end of the fourth resistor is connected to the pulse signal output terminal of the main control module.

[0016] The drain of the MOSFET is connected to the negative terminal of the LED chip.

[0017] The source of the MOS transistor is connected to the common terminal through a third resistor.

[0018] In some embodiments, the graded dimming circuit further includes a fifth resistor.

[0019] One end of the fifth resistor is coupled to the gate of the MOS transistor.

[0020] The other end of the fifth resistor is connected to the common terminal.

[0021] In some embodiments, a power supply circuit is also included, the input of which is connected to the output of the battery assembly, for receiving the voltage signal output by the battery assembly and performing voltage regulation / filtering on the input voltage signal.

[0022] The output terminal of the power supply circuit is connected to the power input terminal of the main control module.

[0023] In some embodiments, the power supply circuit includes at least a voltage regulator module and an output filter module.

[0024] The input terminal of the voltage regulator module is connected to the output terminal of the battery assembly.

[0025] The input terminal of the output filtering module is coupled to the output terminal of the voltage regulator module.

[0026] The output terminal of the output filtering module is connected to the power input terminal of the main control module.

[0027] In some embodiments, the output filtering module includes a fourth capacitor and a fifth capacitor connected in parallel.

[0028] One end of the fourth capacitor and one end of the fifth capacitor are connected to the power input terminal of the main control module.

[0029] The other end of the fourth capacitor and the fifth capacitor are connected to the common terminal.

[0030] In some embodiments, the MOS transistor is selected as an N-channel enhancement-mode MOS transistor.

[0031] The temperature-compensated LED lighting application circuit of this invention includes a temperature detection circuit for acquiring the temperature signal generated when the LED beads are working, a main control module, and a graded dimming circuit. The main control module receives the temperature signal and outputs a PWM signal based on it. The graded dimming circuit receives the PWM signal. The main control module adjusts the duty cycle of the output PWM signal according to the feedback temperature signal to control the graded dimming circuit to dim the LED beads. Compared with existing technologies, by adjusting the duty cycle of the output PWM signal according to the feedback temperature signal, the brightness of the LED beads can be effectively adjusted. This solves the problem that when the temperature of the LED beads increases during operation, the brightness decreases or fluctuates. Furthermore, since the voltage is fixed, the increased current caused by the heated LED beads may damage or shorten their lifespan. Attached Figure Description

[0032] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0033] Figure 1 This is a circuit diagram of an embodiment of the temperature-compensated LED lighting application circuit provided by this utility model. Detailed Implementation

[0034] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0035] like Figure 1 As shown, in the first embodiment of the temperature-compensated LED lighting application circuit of this utility model, the temperature-compensated LED lighting application circuit 10 includes a power supply circuit 110, a temperature detection circuit 120, a main control module MCU, and a graded dimming circuit 130.

[0036] The power supply circuit 110 is used to receive the voltage signal input from the pre-amplifier or battery pack (corresponding to BAT-3.7V) and to perform voltage regulation / filtering on the input voltage signal.

[0037] Temperature detection circuit 120 is used to detect the temperature signal generated when the LED beads are controlled to work or the temperature signal in the space where the LED beads are placed, and feeds the temperature signal back to the main control module MCU.

[0038] The main control module (MCU) is responsible for computation, signal reception / processing, and PWM signal output.

[0039] The graded dimming circuit 130 has the functions of switching and dimming. It is used to receive the PWM signal input by the main control module MCU to control the working state of the LED beads and to dim the LED beads.

[0040] Specifically, the temperature detection circuit 120 is configured on the adjacent side of the LED bead and close to the LED bead, which can be understood as being in contact with the substrate of the LED bead, so as to effectively acquire the temperature signal generated when the LED bead is controlled to work, and feed the acquired temperature signal back to the main control module MCU;

[0041] Furthermore, the input terminal of the main control module MCU is coupled to the output terminal of the temperature detection circuit 120, which is used to receive the temperature signal fed back by the temperature detection circuit 120, and output the PWM signal with adjusted duty cycle according to the temperature signal.

[0042] In this circuit, one end of the graded dimming circuit 130 is connected to one end of the LED lamp bead, and the other end is coupled to the pulse signal output terminal of the main control module MCU to receive PWM signals. The input PWM signals are used to control the switching state of the graded dimming circuit 130.

[0043] Specifically, the main control module MCU adjusts the duty cycle of the output PWM signal according to the feedback temperature signal to control the graded dimming circuit 130 to dim the LED beads.

[0044] Specifically, LED1 (White Lamp) can use high-power white light lamps (or lamps of different color temperatures, depending on the application scenario) to provide lighting source output. The graded dimming circuit 130 is controlled by the PWM signal output by the main control module MCU, with 100 levels of PWM duty cycle, i.e. 0-100% dimming.

[0045] When LED1 (White Lamp) is started normally, as the heat gradually increases, the brightness of the LED will also decrease. At this time, the temperature detection circuit 120 will transmit the signal of the change to the main control module MCU. The main control module MCU can analyze and process the detected temperature value and then control the dimming ratio of the graded dimming circuit 130 through the PWM pin to achieve the effect of temperature compensation.

[0046] Using this technical solution, the main control module adjusts the duty cycle of the output PWM signal according to the feedback temperature signal, thereby adjusting the brightness of the LED beads. This effectively solves the problem that when the temperature of the LED beads increases during operation, the brightness decreases or fluctuates. Since the voltage is fixed, the heated LED beads cause an increase in current, which may damage or shorten the life of the LEDs.

[0047] In some implementations, to ensure the reliability of temperature value acquisition, a thermistor NTC1 and a sixth capacitor C106 can be included in the temperature detection circuit 120.

[0048] Among them, the thermistor NTC1 is used to detect / monitor / identify the temperature change (or temperature signal) of the LED beads, and the sixth capacitor C106 is used to eliminate interference from low-frequency signals;

[0049] Specifically, one end face of the thermistor NTC1 is at least in contact with one end face of the LED chip to acquire the temperature signal generated when the LED chip is working.

[0050] One end of the thermistor NTC1 and the sixth capacitor C106 are connected to the temperature signal terminal of the main control module MCU to receive the temperature signal. The main control module MCU can adjust the duty cycle of the output PWM signal according to the feedback temperature signal.

[0051] In some implementations, to ensure the reliability of LED dimming, a MOSFET Q101 and a fourth resistor R104 can be provided in the graded dimming circuit 130. The MOSFET Q101 has the function of a switch and is selected as an N-channel enhancement-mode MOSFET. The fourth resistor R104 is the gate input resistance of the MOSFET Q101.

[0052] Specifically, the gate of MOSFET Q101 is connected to one end of the fourth resistor R104.

[0053] The other end of the fourth resistor R104 is connected to the pulse signal output terminal of the main control module MCU. The PWM signal output by the main control module MCU is input to the gate of MOSFET Q101 through the fourth resistor R104 to control the on / off state of MOSFET Q101.

[0054] The drain of MOSFET Q101 is connected to the negative terminal of the LED, and the positive terminal of the LED is connected to the positive terminal of the battery pack (corresponding to BAT-3.7V) through the second resistor R102. The current signal output by the battery pack (corresponding to BAT-3.7V) is filtered by the first capacitor C101 and the second capacitor C102 to provide a power signal for the LED to work.

[0055] The source of MOSFET Q101 is connected to the common terminal through the third resistor R103.

[0056] When the input PWM signal is high, the MOSFET Q101 is turned on, and the current flows through the LED, the DS terminal of the MOSFET Q101, and the common terminal to control the LED to turn on.

[0057] When LED1 (White Lamp) is started normally, as the heat gradually increases, the brightness of the LED will also decrease. At this time, the thermistor NTC1 will transmit the temperature change signal to the temperature feedback terminal (corresponding to the NTC terminal) of the main control module MCU. After analyzing and processing the detected temperature value, the main control module MCU controls the dimming ratio of MOSFET Q101 by adjusting the duty cycle of the PWM signal output terminal, thereby achieving the effect of temperature compensation.

[0058] In some implementations, to ensure the reliability of the operation of MOSFET Q101, a fifth resistor R105 can be provided in the graded dimming circuit 130, which is used to release the gate current when MOSFET Q101 is turned off.

[0059] Specifically, one end of the fifth resistor R105 is coupled to the gate of the MOSFET Q101.

[0060] The other end of the fifth resistor R105 is connected to the common terminal.

[0061] In some implementations, to ensure the stability of the MCU main control module, a power supply circuit 110 can be set in the application circuit. The input terminal of the power supply circuit 110 is connected to the output terminal of the battery pack (corresponding to BAT-3.7V) to receive the voltage signal output by the battery pack (corresponding to BAT-3.7V) and perform voltage regulation / filtering on the input voltage signal.

[0062] The output of the power supply circuit 110 is connected to the power input terminal (corresponding to the VCC terminal) of the main control module MCU to provide working power to the main control module MCU.

[0063] In some embodiments, the power supply circuit 110 includes at least a voltage regulator module U101 and an output filter module.

[0064] The input terminal of the voltage regulator module U101 is connected to the output terminal of the battery pack (corresponding to BAT-3.7V).

[0065] The input terminal of the output filter module is coupled to the output terminal of the voltage regulator module U101, and is used to receive the voltage signal after being regulated by the voltage regulator module U101.

[0066] The output of the output filter module is connected to the power input terminal (corresponding to VCC terminal) of the main control module MCU. After filtering the regulated voltage signal, it is then input to the power input terminal (corresponding to VCC terminal) of the main control module MCU.

[0067] In some implementations, the output filtering module includes a fourth capacitor C104 and a fifth capacitor C105 connected in parallel, wherein one end of the fourth capacitor C104 and the fifth capacitor C105 is connected to the power input terminal of the main control module MCU.

[0068] The other ends of the fourth capacitor C104 and the fifth capacitor C105 are connected to the common terminal.

[0069] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A temperature-compensated LED lighting application circuit, characterized by have: A temperature detection circuit is configured on the adjacent side of the LED bead and close to the LED bead to acquire the temperature signal generated when the LED bead is working. The main control module has its input terminal coupled to the output terminal of the temperature detection circuit, and is used to receive the temperature signal and output a PWM signal according to the temperature signal. A graded dimming circuit, one end of which is connected to one end of the LED lamp bead, and the other end is coupled to the pulse signal output terminal of the main control module, for receiving the PWM signal; The main control module adjusts the duty cycle of the output PWM signal according to the feedback temperature signal to control the graded dimming circuit to dim the LED beads.

2. The temperature-compensated LED lighting application circuit according to claim 1, characterized in that, The temperature detection circuit includes at least a thermistor and a sixth capacitor. The thermistor is attached to the LED chip and is used to acquire the temperature signal generated when the LED chip is working. One end of the thermistor and one end of the sixth capacitor are connected to the temperature signal terminal of the main control module to receive the temperature signal.

3. The temperature-compensated LED lighting application circuit according to claim 1 or 2, characterized in that, The graded dimming circuit includes at least a MOSFET and a fourth resistor. The gate of the MOS transistor is connected to one end of the fourth resistor. The other end of the fourth resistor is connected to the pulse signal output terminal of the main control module. The drain of the MOSFET is connected to the negative terminal of the LED chip. The source of the MOS transistor is connected to the common terminal through a third resistor.

4. The temperature-compensated LED lighting application circuit according to claim 3, characterized in that, The graded dimming circuit also includes a fifth resistor. One end of the fifth resistor is coupled to the gate of the MOS transistor. The other end of the fifth resistor is connected to the common terminal.

5. The temperature-compensated LED lighting application circuit according to claim 1, characterized in that, It also includes a power supply circuit, the input of which is connected to the output of the battery assembly, for receiving the voltage signal output by the battery assembly and performing voltage regulation / filtering on the input voltage signal. The output terminal of the power supply circuit is connected to the power input terminal of the main control module.

6. The temperature-compensated LED lighting application circuit according to claim 5, characterized in that, The power supply circuit includes at least a voltage regulator module and an output filter module. The input terminal of the voltage regulator module is connected to the output terminal of the battery assembly. The input terminal of the output filtering module is coupled to the output terminal of the voltage regulator module. The output terminal of the output filtering module is connected to the power input terminal of the main control module.

7. The temperature-compensated LED lighting application circuit according to claim 6, characterized in that, The output filtering module includes a fourth capacitor and a fifth capacitor connected in parallel. One end of the fourth capacitor and one end of the fifth capacitor are connected to the power input terminal of the main control module. The other end of the fourth capacitor and the fifth capacitor are connected to the common terminal.

8. The temperature-compensated LED lighting application circuit of claim 4, wherein: the MOS transistor is an N-channel enhancement-mode MOS transistor.

Images