A thermal sensing control circuit for over-temperature protection of an LED driving power supply

Abstract

The utility model discloses a kind of over-temperature protection LED drive power thermal induction control circuit, including linear compensation circuit, the one end of linear compensation circuit is connected with bandgap reference core circuit, temperature decision circuit is equipped in the side of bandgap reference core circuit, a kind of over-temperature protection LED drive power thermal induction control circuit of the utility model, the output end of reference voltage and positive temperature coefficient voltage is respectively connected in the input end of comparator and is compared, the result obtained after output passes through three inverters then controls the work of LED drive circuit, when temperature is greater than temperature maximum early-warning value, turn off circuit, circuit is also set hysteresis interval, and hysteresis interval size is adjustable, setting hysteresis interval can avoid circuit frequent conduction to cause noise, circuit is also designed temperature adaptive circuit, temperature adaptive voltage is generated by temperature adaptive current, under the condition that voltage is invariable, power reduces, to reduce heat generation, effectively inhibit temperature rise.

Description

Technical Field

[0001] This utility model relates to the field of thermal sensing control circuit technology, specifically to a thermal sensing control circuit for an LED driver power supply with over-temperature protection. Background Technology

[0002] Thermal sensing control circuits, such as thermocouples, can cover a wide temperature range from -200℃ to over 2000℃, making them suitable for various extreme temperature environments. Because they directly convert signals through physical effects such as thermoelectric effects, thermal sensing control circuits have fast response speeds and low delays. They are typically composed of two different metals joined together, eliminating complex components and reducing system complexity. Thermal sensing control circuits autonomously generate thermoelectric potential based on the Seebeck effect, reducing system complexity. Since they are in direct contact with the object being measured, they are unaffected by intermediate media, resulting in high measurement accuracy. However, traditional thermal sensing control circuits have the following drawbacks: Traditional thermal sensing control circuits simply drive LEDs to turn on or off by controlling temperature, which cannot meet the requirement of LEDs being safely driven in complex environments. Utility Model Content

[0003] The purpose of this invention is to provide an over-temperature protection LED driver power supply thermal sensing control circuit to solve the problem mentioned in the background art that the traditional thermal sensing control circuit can only drive or turn off the LED lamp by controlling the temperature, which cannot meet the requirement of LED being safely driven in complex environments.

[0004] To achieve the above objectives, this utility model provides the following technical solution: an over-temperature protection LED driver power supply thermal sensing control circuit, comprising a linear compensation circuit, one end of which is connected to a bandgap reference core circuit, a temperature decision circuit on one side of the bandgap reference core circuit, one end of which is connected to a temperature adaptive control circuit, one end of which is connected to a hysteresis shutdown circuit, one end of which and one end of which are both connected to an LED driver circuit, one end of which is connected to a constant current circuit, and one end of which is connected to an LED lamp.

[0005] Preferably, the bandgap reference core circuit includes a first-order correction reference voltage source circuit and a second-order adjustment correction bandgap reference circuit. The first-order correction reference voltage source circuit includes MOSFETs M0, M1, M2, M3, M4, M5, M6, M7, M8, M9, and M10, resistors R0 and R1, and transistor Q0. One end of transistor Q0 is connected to one end of resistor R1, and the other end of resistor R1 is connected to pin 1 of MOSFET M10. Pins 2 of MOSFET M10 are respectively connected to pins 1 of MOSFETs M5, M4, and M10. Pin 1 of MOSFET M3 is connected to pin 3 of MOSFET M6. Pin 2 of MOSFET M6 is connected to pin 1 of MOSFET M7. Pin 2 of MOSFET M7 is connected to pin 1 of MOSFET M8. Pin 1 of MOSFET M6 and pin 3 of MOSFET M7 are both connected to one end of resistor R0. The other end of resistor R0 and pin 2 of MOSFET M8 are both connected to the other end of transistor Q0. Pin 3 of MOSFET M10 is connected to pin 1 of MOSFET M9. Pin 2 of MOSFET M9 is connected to pins 1 of MOSFET M2, pin 1 of MOSFET M1, and pin 1 of MOSFET M0, respectively.

[0006] Preferably, the LED driving circuit includes MOSFETs M25, M26, M27, M28, and M29, and resistor R7. One end of the bandgap reference core circuit is connected to pin 1 of MOSFET M25, pin 2 of MOSFET M25 is connected to one end of resistor R7, the other end of resistor R7 and pin 3 of MOSFET M25 are both connected to pin 1 of MOSFET M26, and pin 2 of MOSFET M26 is connected to pins 1 of MOSFET M27, pin 1 of MOSFET M28, and pin 1 of MOSFET M29, respectively.

[0007] Preferably, the temperature decision circuit includes a MOSFET M0 and a MOSFET M1, with one end of the MOSFET M0 connected to one end of the MOSFET M1.

[0008] Preferably, the constant current circuit includes a MOSFET M0 and a resistor R. S One end of the MOS transistor M0 is connected to the resistor R. S One end is connected, the resistor R S The other end is grounded.

[0009] Compared with the prior art, the beneficial effects of this utility model are as follows: the output terminals of the reference voltage and the positive temperature coefficient voltage are respectively connected to the input terminals of the comparator for comparison. The output result is passed through a three-stage inverter and then controls the operation of the LED driving circuit. When the temperature exceeds the maximum temperature warning value, the circuit is turned off, so that the LED does not work. The circuit also has a hysteresis interval, and the size of the hysteresis interval is adjustable. Setting the hysteresis interval can avoid the noise caused by frequent circuit conduction. The circuit is also designed with a temperature adaptive circuit, which generates a temperature adaptive voltage from the temperature adaptive current. The adaptive voltage acts on the LED driving circuit, so that when the temperature rises to a certain level, but not to the point of overheating and shutdown, the adaptive circuit plays a role, so that the LED current gradually decreases with the temperature. Under the condition of constant voltage, the power decreases, thereby reducing heat generation and effectively suppressing the temperature rise. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the architecture of this utility model; Figure 2 This is a circuit diagram of the first-order correction reference voltage source circuit of this utility model; Figure 3 This is a circuit diagram of the LED driver circuit of this utility model; Figure 4 This is a circuit diagram of the temperature determination circuit of this utility model; Figure 5 This is the circuit diagram of the constant current circuit of this utility model. Detailed Implementation

[0011] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0012] Please see Figure 1-5 This utility model provides an over-temperature protection LED driver power supply thermal sensing control circuit, including a linear compensation circuit. One end of the linear compensation circuit is connected to a bandgap reference core circuit. A temperature decision circuit is provided on one side of the bandgap reference core circuit. One end of the bandgap reference core circuit is connected to a temperature adaptive control circuit. One end of the temperature decision circuit is connected to a hysteresis shutdown circuit. One end of the temperature adaptive control circuit and one end of the hysteresis shutdown circuit are both connected to an LED driver circuit. One end of the LED driver circuit is connected to a constant current circuit. One end of the constant current circuit is connected to an LED lamp.

[0013] The core circuit of the bandgap reference includes a first-order calibration reference voltage source circuit and a second-order adjustment calibration bandgap reference circuit. The first-order calibration reference voltage source circuit includes MOSFETs M0, M1, M2, M3, M4, M5, M6, M7, M8, M9, and M10, resistors R0 and R1, and transistor Q0. One end of transistor Q0 is connected to one end of resistor R1, and the other end of resistor R1 is connected to pin 1 of MOSFET M10. Pins 2 of MOSFET M10 are connected to pins 1 of MOSFETs M5 and M4, respectively. Pin 1 of MOSFET M3 is connected to pin 3 of MOSFET M6. Pin 2 of MOSFET M6 is connected to pin 1 of MOSFET M7. Pin 2 of MOSFET M7 is connected to pin 1 of MOSFET M8. Pin 1 of MOSFET M6 and pin 3 of MOSFET M7 are both connected to one end of resistor R0. The other end of resistor R0 and pin 2 of MOSFET M8 are both connected to the other end of transistor Q0. Pin 3 of MOSFET M10 is connected to pin 1 of MOSFET M9. Pin 2 of MOSFET M9 is connected to pin 1 of MOSFET M2, pin 1 of MOSFET M1, and pin 1 of MOSFET M0, respectively.

[0014] The LED driver circuit includes MOSFETs M25, M26, M27, M28, and M29, and resistor R7. One end of the bandgap reference core circuit is connected to pin 1 of MOSFET M25. Pin 2 of MOSFET M25 is connected to one end of resistor R7. The other end of resistor R7 and pin 3 of MOSFET M25 are both connected to pin 1 of MOSFET M26. Pin 2 of MOSFET M26 is connected to pins 1 of MOSFET M27, pin 1 of MOSFET M28, and pin 1 of MOSFET M29, respectively.

[0015] The temperature decision circuit includes MOSFET M0 and MOSFET M1, with one end of MOSFET M0 connected to one end of MOSFET M1.

[0016] The constant current circuit includes a MOSFET M0 and a resistor R. S One end of the MOSFET M0 is connected to the resistor R. S One end is connected to resistor R S The other end is grounded.

[0017] In this embodiment, the linear compensation circuit is divided into low-temperature stage linear compensation and high-temperature stage linear compensation. Low-temperature stage linear adjustment generates a current that decreases with increasing temperature, using a cascode current mirror. At the node convergence point in the low-temperature stage, the negative temperature coefficient of CTAT (decreases with increasing temperature) is greater than the positive temperature coefficient of PTAT (increases with increasing temperature). According to KCL theorem, the CTAT current can be obtained. Similarly, high-temperature stage linear compensation generates a positive temperature coefficient current, also primarily generated by the cascode current mirror. At the node convergence point in the high-temperature stage, the PTAT current is greater than the CTAT current. At the node convergence point, the PTAT current Ih is obtained according to KCL theorem. Negative temperature coefficient current adjustment is performed in the low-temperature stage. In the high-temperature stage, positive temperature coefficient current adjustment is performed to obtain a reference voltage with a smaller temperature drift coefficient, resulting in more accurate voltage. The bandgap reference core circuit adopts a negative feedback loop, which improves the circuit's PSRR and reduces the impact of voltage changes on the current source. The current generated by the bandgap reference core circuit, along with the compensation current in the low-temperature and high-temperature stages, flows into the reference resistor circuit, resulting in a lower voltage temperature coefficient and greater accuracy. The adaptive control circuit generates a negative temperature coefficient voltage, which decreases with temperature, acting on the main circuit of the driver circuit to produce a negative temperature coefficient current, thereby adjusting the LED current. This reduces power consumption and suppresses temperature rise, effectively protecting the circuit. The temperature decision circuit compares the reference voltage with the PTAT voltage generated by the reference circuit to output a comparison voltage. A common-source common-gate comparator is used. The hysteresis turn-off circuit uses the output voltage generated by the temperature decision module, which is passed through a three-stage inverter to obtain the hysteresis turn-off voltage, which is then applied to the LED driver circuit. When uncontrollable factors cause the temperature to become too high, the LED driver circuit is shut down. The circuit only restarts when the temperature drops back to the set safe temperature, thus achieving a hysteresis shutdown effect and effectively preventing thermal oscillation. In the LED driver circuit, when the chip temperature is below the adaptive control temperature, the current output is a constant 350mA. When the chip temperature is above the adaptive control temperature but below the hysteresis shutdown over-temperature protection temperature, the adaptive module activates, and the current gradually decreases with temperature, reducing power loss and suppressing temperature rise. When the chip temperature reaches the maximum temperature warning setting point, the hysteresis shutdown module activates, causing the driver circuit to stop working. The driver circuit only restarts when the temperature drops back to the low-temperature hysteresis point.

[0018] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A thermal sensing control circuit for an over-temperature protection LED driver power supply, comprising a linear compensation circuit, characterized in that: One end of the linear compensation circuit is connected to a bandgap reference core circuit. A temperature decision circuit is provided on one side of the bandgap reference core circuit. One end of the bandgap reference core circuit is connected to a temperature adaptive control circuit. One end of the temperature decision circuit is connected to a hysteresis shutdown circuit. One end of the temperature adaptive control circuit and one end of the hysteresis shutdown circuit are both connected to an LED driver circuit. One end of the LED driver circuit is connected to a constant current circuit. One end of the constant current circuit is connected to an LED lamp.

2. The over-temperature protection LED driver power supply thermal sensing control circuit according to claim 1, characterized in that: The core circuit of the bandgap reference includes a first-order correction reference voltage source circuit and a second-order adjustment correction bandgap reference circuit. The first-order correction reference voltage source circuit includes MOSFETs M0, M1, M2, M3, M4, M5, M6, M7, M8, M9, and M10, resistors R0 and R1, and transistor Q0. One end of transistor Q0 is connected to one end of resistor R1, and the other end of resistor R1 is connected to pin 1 of MOSFET M10. Pins 2 of MOSFET M10 are respectively connected to pins 1 of MOSFET M5, pin 1 of MOSFET M4, and pin 2 of MOSFET M10. Pin 1 of transistor M3 is connected to pin 3 of transistor M6. Pin 2 of transistor M6 is connected to pin 1 of transistor M7. Pin 2 of transistor M7 is connected to pin 1 of transistor M8. Pin 1 of transistor M6 and pin 3 of transistor M7 are both connected to one end of resistor R0. The other end of resistor R0 and pin 2 of transistor M8 are both connected to the other end of transistor Q0. Pin 3 of transistor M10 is connected to pin 1 of transistor M9. Pin 2 of transistor M9 is connected to pin 1 of transistor M2, pin 1 of transistor M1, and pin 1 of transistor M0, respectively.

3. The over-temperature protection LED driver power supply thermal sensing control circuit according to claim 1, characterized in that: The LED driving circuit includes MOSFETs M25, M26, M27, M28, and M29, and resistor R7. One end of the bandgap reference core circuit is connected to pin 1 of MOSFET M25. Pin 2 of MOSFET M25 is connected to one end of resistor R7. The other end of resistor R7 and pin 3 of MOSFET M25 are both connected to pin 1 of MOSFET M26. Pin 2 of MOSFET M26 is connected to pins 1 of MOSFET M27, pin 1 of MOSFET M28, and pin 1 of MOSFET M29, respectively.

4. The over-temperature protection LED driver power supply thermal sensing control circuit according to claim 1, characterized in that: The temperature decision circuit includes MOSFET M0 and MOSFET M1, with one end of MOSFET M0 connected to one end of MOSFET M1.

5. The over-temperature protection LED driver power supply thermal sensing control circuit according to claim 1, characterized in that: The constant current circuit includes a MOSFET M0 and a resistor R. S One end of the MOS transistor M0 is connected to the resistor R. S One end is connected, the resistor R S The other end is grounded.

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