A LED constant current controller with over-temperature regulation
By introducing a voltage comparator and over-temperature drop-down adjustment module into the LED constant current controller, the output current is reduced to balance the chip temperature, and the LED flickering and shutdown problems caused by chip over-temperature is solved, achieving stable and safe lighting effects .
Patent Information
- Application Number
- CN202011486298.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2020-12-16
- Publication Date
- 2025-01-03
- Estimated Expiration
- 2040-12-16
AI Technical Summary
Existing LED constant current controllers can easily cause LED flashing or shutdown when the chip is overtempered, causing inconvenience, especially during night lighting, and there is a fire risk.
A constant current controller with over-temperature regulation is designed. By introducing voltage comparator, NMOS tube and over-temperature drop-current regulation module into the internal and peripheral circuits of the chip, the output current is reduced to balance the chip temperature and LED lighting. This avoids flickering and shutdown. The controller includes a voltage comparator, NMOS tube, feedback resistor and over-temperature flow reduction adjustment module. It uses components such as capacitance adjustment circuit and Schmitt trigger to adjust the conduction and shutdown of the NMOS tube to achieve temperature cooling.
Effectively avoid LED flickering and shutdown, ensure the normal operation of the chip, reduce the temperature, avoid fire risks, and improve the stability of LED lighting.
Smart Images
Figure CN112492721B_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of lighting circuits and relates to an LED constant current controller with over-temperature regulation. Background Art
[0002] In recent years, with the gradual improvement of economic level, outdoor lighting applications have become more and more widespread, such as lighting equipment in parks, squares and outdoor advertising lights. In particular, the control chip and solution of low standby power consumption of solar lawn lights have been widely developed and applied. Through the LED drive controller with constant current function, it realizes the use of multiple functions and takes green environmental protection into consideration at the same time, and can be applied to various environments and occasions.
[0003] In LED constant current applications, in order to save peripheral application costs, feedback resistors and MOS tubes used for driving are often set inside the chip. And let the technicians know that since the power tube is built inside the chip and is in a sealed environment, when used for a long time or driven with a large current, the temperature inside the chip will gradually rise. When the temperature reaches a certain temperature, the chip parameters will deviate greatly, and the temperature will continue to rise, which will cause the chip to burn and cause a fire.
[0004] In the prior art, the over-temperature protection is often handled by shutting down the chip output when the temperature exceeds a certain level, and restarting the chip after the temperature drops. However, this will cause the lighting LED to alternately light up and off, which will cause great inconvenience especially at night.
[0005] Therefore, when the chip is overheated, how to protect the chip has become an urgent problem that needs to be solved in the industry. Summary of the invention
[0006] In order to solve the above technical problems, the present invention proposes a new LED constant current controller and method with over-temperature regulation, which can effectively solve the problem of over-temperature protection LED flickering or shutdown in LED constant current applications. When the chip temperature rises, the output current can be reduced to achieve a balance between the chip temperature and LED lighting, thereby avoiding the problem of LED flickering and shutdown.
[0007] To achieve the above object, the technical solution of the present invention is as follows:
[0008] An LED constant current controller with over-temperature regulation includes: a chip internal circuit and a chip peripheral circuit; the peripheral circuit includes an illumination LED and a power supply terminal VDD;
[0009] The internal circuit includes a voltage comparator CMP, an NMOS tube N0, a feedback resistor R0 and an over-temperature current reduction regulation module;
[0010] The positive electrode of the lighting LED is connected to the power supply terminal VDD, the negative electrode of the LED is connected to the chip pin LX and connected to the drain of the internal NMOS tube N0; the positive electrode of the voltage comparator CMP is connected to the reference voltage Vref, the negative terminal of the voltage comparator CMP is connected to the connection point of the feedback resistor R0 and the source of the NMOS tube N0, the output of the voltage comparator CMP is connected to the connection point of the gate of the NMOS tube N0 and the output terminal GT of the over-temperature current reduction regulation module, and the other end of the resistor R0 is connected to the chip ground terminal GND;
[0011] When the chip starts to supply power to the lighting LED, the voltage at one end of the feedback resistor R0 is equal to the reference voltage Vref. When the chip temperature rises to a predetermined temperature, the over-temperature current reduction regulation module starts to work, controlling the gate of the NMOS tube N0 to reduce the output current of the lighting LED.
[0012] Furthermore, the over-temperature current reduction regulation module includes: a bias current I, a capacitor adjustment circuit, a Schmitt trigger SMT1, an NMOS tube N4, an NMOS tube N5, an NMOS tube N6, an inverter INV1, an inverter INV2, and a capacitor C4; wherein the bias current I is connected to the output end OUT1 of the capacitor adjustment circuit, the input end of the Schmitt trigger SMT1, and the drain of the NMOS tube N6; the output end of the Schmitt trigger SMT1 is connected to the gates of the NMOS tube N4 and the NMOS tube N5; one end of the capacitor C4, the bias current I2, and the drain of the NMOS tube N4 are connected to the gates of the NMOS tube N5. The gate of the NMOS tube N6 is connected to the output terminal OUT2 of the capacitor adjustment circuit, the source of the NMOS tube N6 is connected to the drain of the NMOS tube N3, the sources of the NMOS tubes N3, NMOS tubes N4 and NMOS tubes N5 and the other end of the capacitor C4 are connected to the chip ground terminal GND, and the drain of the NMOS tube N5 is the output terminal of the over-temperature current reduction regulation module.
[0013] Further, the capacitance adjustment circuit includes a resistor R1, a resistor R2, a resistor R3, a first comparator CMP1, a second comparator CMP2, an NMOS tube N1, an NMOS tube N2, a capacitor C1 and a capacitor C2;
[0014] Wherein, a reference voltage Vref is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2 and the positive input end of the first comparator CMP1, the other end of the resistor R2 is connected to one end of the resistor R3 and the positive input end of the second comparator CMP2, the negative ends of the first comparator CMP1 and the second comparator CMP2 are both connected to the voltage end Vbe, the output of the first comparator CMP1 is connected to the gate of the NMOS transistor N2, the gate of the NMOS transistor N2 is the output end OUT2, the output end of the second comparator CMP2 is connected to the gate of the NMOS transistor N1, the source of the NMOS transistor N1 is connected to one end of the capacitor C1, the source of the NMOS transistor N2 is connected to one end of the capacitor C2, the other end of the resistor R3 and the other ends of the capacitor C1 and the capacitor C2 are connected to the ground end GND; the NMOS transistor N1 is connected to the drain of the NMOS transistor N2, and the drain of the NMOS transistor N1 is the output end OUT1.
[0015] Furthermore, the voltage of the voltage terminal Vbe is the base-emitter voltage of the transistor PNP, and the voltage of the voltage terminal Vbe is inversely proportional to the temperature value inside the chip.
[0016] Furthermore, the capacitor C2 and the resistor R3 are placed outside the chip, the capacitor C2 is an adjustable capacitor, and the resistor R3 is an adjustable resistor.
[0017] Furthermore, the capacitance adjustment circuit includes a resistor R3, a first comparator CMP1, an NMOS tube N2 and a capacitor C2; wherein a reference voltage Vref is connected to the positive input terminal of the first comparator CMP1 and one end of the resistor R3, the negative end of the first comparator CMP1 is connected to the voltage terminal Vbe, the output of the first comparator CMP1 is connected to the gate of the NMOS tube N2, the output end of the second comparator CMP2 is connected to the gate of the NMOS tube N1, the source of the NMOS tube N2 is connected to one end of the capacitor C2, and the other end of the resistor R3 and the other end of the capacitor C2 are connected to the ground terminal GND.
[0018] Furthermore, the NMOS tube N0 is an NPN tube.
[0019] Furthermore, the NMOS tube N3, the NMOS tube N4 or the NMOS tube N5 is an NPN tube.
[0020] Furthermore, the NMOS tube N1 or the NMOS tube N2 is an NPN tube.
[0021] It can be seen from the above technical solution that the LED constant current controller with over-temperature regulation of the present invention can avoid excessive internal temperature of the chip by reducing the output current when the chip works for a long time or outputs a large current, thereby ensuring the normal operation of the chip. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 FIG. 1 is a schematic diagram of an LED constant current controller circuit with over-temperature regulation in an embodiment of the present invention.
[0023] Figure 2 The schematic diagram of the temperature drop flow regulation module in the embodiment of the present invention is shown as follows
[0024] Figure 3 FIG. 1 is a schematic diagram showing a structure of a capacitance adjustment circuit in an embodiment of the present invention.
[0025] Figure 4 Schematic diagram showing waveforms of various nodes of an LED constant current controller with over-temperature regulation in an embodiment of the present invention DETAILED DESCRIPTION
[0026] The following is combined with Figure 1-4 , the specific implementation modes of the present invention are further described in detail.
[0027] See also Figure 1 , Figure 1 The figure shows a schematic diagram of an LED constant current controller circuit with over-temperature regulation in an embodiment of the present invention. As shown in the figure, the LED constant current controller with over-temperature regulation of the present invention includes a chip internal circuit and a chip peripheral circuit; the peripheral circuit includes an illumination LED and a power supply terminal VDD.
[0028] The internal circuit includes a voltage comparator CMP, an NMOS tube N0, a feedback resistor R0 and an over-temperature current reduction regulation module; wherein the positive electrode of the lighting LED is connected to the power supply terminal VDD, the negative electrode of the LED is connected to the chip pin LX and connected to the drain of the internal NMOS tube N0; the positive electrode of the voltage comparator CMP is connected to the reference voltage Vref, the negative terminal of the voltage comparator CMP is connected to the connection point of the feedback resistor R0 and the source of the NMOS tube N0, the output of the voltage comparator CMP is connected to the connection point of the gate of the NMOS tube N0 and the over-temperature current reduction regulation module terminal GT, and the other end of the resistor R0 is connected to the chip ground terminal GND.
[0029] The working principle of the present invention is as follows: when the chip starts to supply power to the lighting LED, through the form of negative feedback, the voltage at one end of the feedback resistor R0 is equal to the reference voltage Vref, and at this time the LED current is I=Vref / R0, thereby achieving a constant current effect. When the chip temperature rises to a predetermined temperature, the over-temperature current reduction regulation module starts to work, so that the gate of the NMOS tube N0 starts to change, that is, the gate of the NMOS tube N0 is controlled to reduce the output current of the lighting LED.
[0030] See also Figure 2 , Figure 2 FIG. 1 is a schematic diagram of a temperature drop flow regulation module according to an embodiment of the present invention. Figure 2 As shown, the over-temperature current reduction regulation module in the embodiment of the present invention has the following circuit connection method: the over-temperature current reduction regulation module includes: a bias current I, a capacitor adjustment circuit, a Schmitt trigger SMT1, an NMOS tube N4, an NMOS tube N5, an NMOS tube N6, an inverter INV1, an inverter INV2, and a capacitor C4. The bias current I is connected to the output end OUT1 of the capacitor adjustment circuit, the input end of the Schmitt trigger SMT1 and the drain of the NMOS tube N6; the output end of the Schmitt trigger SMT1 is connected to the gates of the NMOS tubes N4 and NMOS tubes N5; one end of the capacitor C4, the bias current I2, the drain of the NMOS tube N4 and the input end of the inverter INV2 are connected together, the output end of the inverter INV2 is connected to the input end of the inverter INV1, the output end of the inverter INV1 is connected to the gate of the NMOS tube N3, the gate of the NMOS tube N6 is connected to the output end OUT2 of the capacitor adjustment circuit, the source of the NMOS tube N6 is connected to the drain of the NMOS tube N3, the sources of the NMOS tubes N3, NMOS tubes N4 and NMOS tubes N5 and the other end of the capacitor C4 are connected to the chip ground GND, and the drain of the NMOS tube N5 is the output end GT of the over-temperature current reduction regulation module.
[0031] like Figure 2 As shown, the working principle of the over-temperature current reduction regulation module is:
[0032] When the output terminal OUT2 signal is low, the NMOS tube N6 is turned off. At this time, the output terminal OU1 signal is pulled up by the bias current I, and the level is high. After passing through the Schmitt trigger, the gate signal of the NMOS tube N5 is low. Figure 1As shown, at this time, the over-temperature current reduction regulation module has no effect on the LED constant current controller, and the constant current can work normally; when the OUT2 signal is high, the NMOS tube N6 is turned on, and the bias current I charges the capacitor adjustment circuit. When the Schmitt trigger SMT1 flip voltage is met, the NMOS tube N4 is turned off at this time, and the bias current charges the capacitor C4. When the second inverter INV2 flip level is met, the second inverter INV2 output is low, and after the first inverter INV1, the NMOS tube N3 is turned on. At this time, the output terminal OUT1 signal is pulled low, the Schmitt trigger SMT1 signal is high, the NMOS tube N4 is turned on, and the second inverter INV2 signal is low, thereby turning off the NMOS tube 3, and OUT1 is charged by the bias current again.
[0033] Through the above working method, the gate level of NMOS tube 5 can be changed to form an oscillation signal with a certain on-time and off-time. This signal can cause Figure 1 The constant current circuit NMOS tube N0 is turned on and off to achieve the current reduction effect of the LED. At the same time, the heat loss of the NMOS tube N0 inside the chip is adjusted to cool the chip.
[0034] See also Figure 3 , Figure 3 FIG. 1 is a schematic diagram of the structure of the capacitance adjustment circuit in an embodiment of the present invention. Figure 3 As shown, the capacitor adjustment circuit has the following circuit connection method:
[0035] The capacitance adjustment circuit includes a resistor R1, a resistor R2, a resistor R3, a first comparator CMP1, a second comparator CMP2, an NMOS transistor N1, an NMOS transistor N2, a capacitor C1 and a capacitor C2.
[0036] Wherein, the reference voltage Vref is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2 and the positive input end of the first comparator CMP1, the other end of the resistor R2 is connected to one end of the resistor R3 and the positive input end of the second comparator CMP2, the negative ends of the first comparator CMP1 and the second comparator CMP2 are both connected to the voltage end Vbe, the output of the first comparator CMP1 is connected to the gate of the NMOS transistor N2, the gate of the NMOS transistor N2 is the output end OUT2, the output end of the second comparator CMP2 is connected to the gate of the NMOS transistor N1, the source of N1 is connected to one end of the capacitor C1, the source of the NMOS transistor N2 is connected to one end of the capacitor C2, the other end of the resistor R3 and the other ends of the capacitor C1 and the capacitor C2 are connected to the ground end GND; the NMOS transistor N2 is connected to the drain of the NMOS transistor N2, and the drain of the NMOS transistor N1 is the output end OUT1.
[0037] Please continue reading Figure 3 , Figure 3 The capacitor adjustment circuit shown works as follows:
[0038] At normal temperature and normal conditions, the positive terminal voltages of the first comparator CMP1 and the second comparator CMP2 are both less than Vbe, as shown in the following formula:
[0039] (R3+R2) / (R1+R2+R3)*Vref <Vbe
[0040] R3 / (R1+R2+R3)*Vref <Vbe
[0041] At this time, the gate voltage of NMOS tube N1 and NMOS tube N2 is low, and both tubes are turned off, so that the capacitor adjustment circuit has no capacitance to ground, and the OUT2 signal is low at this time, making Figure 2 The oscillator shown cannot work, so that the NMOS tube N5 is turned off, and thus cannot affect the operation of the LED constant current circuit. As the temperature gradually rises, when the positive terminal voltage of the second comparator CMP2 is greater than Vbe, the positive terminal voltage of the first comparator CMP1 is less than Vbe, as shown in the following formula:
[0042] (R3+R2) / (R1+R2+R3)*Vref>Vbe
[0043] R3 / (R1+R2+R3)*Vref <Vbe
[0044] At this time, the NMOS tube N1 is turned off, and the NMOS tube N2 is turned on, so that the capacitor adjustment circuit is the voltage from the capacitor C2 to the ground terminal GND, and the output terminal OUT2 signal is high. Figure 2 If the Schmitt trigger SMT1 shown works normally, the NMOS tube N5 will have an oscillation signal, thereby affecting the on and off of the NMOS tube N0, and further affecting the operation of the LED constant current circuit, achieving the effect of current reduction.
[0045] If the time continues to extend or the current reduction amplitude is insufficient, the temperature continues to rise. When the positive terminal voltages of the second comparator CMP2 and the first comparator CMP1 are both greater than Vbe, as shown in the following formula:
[0046] (R3+R2) / (R1+R2+R3)*Vref>Vbe
[0047] R3 / (R1+R2+R3)*Vref>Vbe
[0048] At this time, both the NMOS transistor N1 and the NMOS transistor N2 are turned on, so that the capacitance adjustment circuit is (C2+C1) to the ground terminal GND capacitance, so that Figure 2The oscillator shown works normally and the NMOS tube N5 is turned on for a longer time, thereby affecting the on and off time of the NMOS tube N0, and then affecting the LED constant current circuit to further reduce the current, thereby achieving the effect of further reducing the current.
[0049] See also Figure 4 , Figure 4 FIG. 1 is a schematic diagram showing waveforms of various nodes of an LED constant current controller with over-temperature regulation in an embodiment of the present invention. Figure 4 As shown, as the temperature increases, Vbe gradually decreases, which can control the conduction of NMOS tubes N2 and NMOS tubes N1 in turn, and then control the conduction and shutdown of the output NMOS tube N0, thereby affecting the current of the output LED and achieving the effect of current reduction regulation.
[0050] In some embodiments of the present invention, a simplified circuit may also be used, that is, only including Figure 3 The resistor R3, the first comparator CMP1, the NMOS tube N2 and the capacitor C2 in the capacitor adjustment circuit can also realize the technical solution of the present invention. The specific circuit is: the capacitor adjustment circuit includes a resistor R3, a first comparator CMP1, an NMOS tube N2 and a capacitor C2; wherein the reference voltage Vref is connected to the positive input end of the first comparator CMP1 and one end of the resistor R3, the negative end of the first comparator CMP1 is connected to the voltage end Vbe, the output of the first comparator CMP1 is connected to the gate of the NMOS tube N2, the output end of the second comparator CMP2 is connected to the gate of the NMOS tube N1, the source of the NMOS tube N2 is connected to one end of the capacitor C2, and the other end of the resistor R3 and the other end of the capacitor C2 are connected to the ground end GND.
[0051] In addition, in the above-mentioned embodiment of the present invention, the over-temperature point (preset temperature) and the current reduction range can be flexibly adjusted as required by adjusting the values of the capacitor C2 and the resistor R3. In actual operation, in order to facilitate the adjustment by the customer, the capacitor C2 and the resistor R3 can be placed outside the chip.
[0052] That is to say, the present invention can adjust the on-off time of the LED constant current circuit N0 by adjusting the grounding capacitor of the over-temperature current reduction regulation module, and in the embodiment of the invention, by selecting the external connection of the resistor R3 and the capacitor C2, the over-temperature regulation point and the current reduction amplitude can be adjusted more flexibly during application.
[0053] Furthermore, the NMOS transistors N1, NMOS transistors N2, NMOS transistors N3, NMOS transistors N4 or NMOS transistors N5 used in the embodiments of the present invention can be replaced with NPN transistors. In summary, the present invention can effectively change the heat loss of the internal NMOS transistors and thus improve the temperature regulation inside the chip.
[0054] The above-described embodiments are only preferred embodiments of the present invention, and the embodiments are not intended to limit the patent protection scope of the present invention. Therefore, any equivalent structural changes made using the description and drawings of the present invention should also be included in the protection scope of the present invention.
Claims
1. An LED constant current controller with over-temperature regulation, characterized in that: include: Chip internal circuits and chip peripheral circuits; The peripheral circuit includes an illumination LED and a power supply terminal VDD; The internal circuit includes a voltage comparator CMP, an NMOS tube N0, a feedback resistor R0 and an over-temperature current reduction regulation module; The positive electrode of the lighting LED is connected to the power supply terminal VDD, the negative electrode of the LED is connected to the chip pin LX and connected to the drain of the internal NMOS tube N0; the positive electrode of the voltage comparator CMP is connected to the reference voltage Vref, the negative terminal of the voltage comparator CMP is connected to the connection point of the feedback resistor R0 and the source of the NMOS tube N0, the output of the voltage comparator CMP is connected to the connection point of the gate of the NMOS tube N0 and the output terminal GT of the over-temperature current reduction regulation module, and the other end of the resistor R0 is connected to the chip ground terminal GND; When the chip starts to supply power to the lighting LED, the voltage at one end of the feedback resistor R0 is equal to the reference voltage Vref. When the chip temperature rises to a predetermined temperature, the over-temperature current reduction regulation module starts to work, controlling the gate of the NMOS tube N0 to reduce the output current of the lighting LED. The over-temperature current reduction regulation module includes: a bias current I, a capacitor regulation circuit, a Schmitt trigger SMT1, an NMOS tube N4, an NMOS tube N5, an NMOS tube N6, an inverter INV1, an inverter INV2, and a capacitor C4; Wherein, the bias current I is connected to the output end OUT1 of the capacitor adjustment circuit, the input end of the Schmitt trigger SMT1 and the drain of the NMOS tube N6; the output end of the Schmitt trigger SMT1 is connected to the gates of the NMOS tubes N4 and NMOS tubes N5; one end of the capacitor C4, the bias current I2, the drain of the NMOS tube N4 and the input end of the inverter INV2 are connected together, the output end of the inverter INV2 is connected to the input end of the inverter INV1, the output end of the inverter INV1 is connected to the gate of the NMOS tube N3, the gate of the NMOS tube N6 is connected to the output end OUT2 of the capacitor adjustment circuit, the source of the NMOS tube N6 is connected to the drain of the NMOS tube N3, the sources of the NMOS tubes N3, NMOS tubes N4 and NMOS tubes N5 and the other end of the capacitor C4 are connected to the chip ground GND, and the drain of the NMOS tube N5 is the output end of the over-temperature current reduction regulation module; The NMOS tube N0 is an NPN tube.
2. The LED constant current controller with over-temperature regulation according to claim 1; characterized in that: The capacitance adjustment circuit includes a resistor R1, a resistor R2, a resistor R3, a first comparator CMP1, a second comparator CMP2, an NMOS transistor N1, an NMOS transistor N2, a capacitor C1 and a capacitor C2; Wherein, a reference voltage Vref is connected to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the resistor R2 and the positive input end of the first comparator CMP1, the other end of the resistor R2 is connected to one end of the resistor R3 and the positive input end of the second comparator CMP2, the negative ends of the first comparator CMP1 and the second comparator CMP2 are both connected to the voltage end Vbe, the output of the first comparator CMP1 is connected to the gate of the NMOS transistor N2, the gate of the NMOS transistor N2 is the output end OUT2, the output end of the second comparator CMP2 is connected to the gate of the NMOS transistor N1, the source of the NMOS transistor N1 is connected to one end of the capacitor C1, the source of the NMOS transistor N2 is connected to one end of the capacitor C2, the other end of the resistor R3 and the other ends of the capacitor C1 and the capacitor C2 are connected to the ground end GND; the NMOS transistor N1 is connected to the drain of the NMOS transistor N2, and the drain of the NMOS transistor N1 is the output end OUT1.
3. The LED constant current controller with over-temperature regulation according to claim 2; characterized in that: The voltage of the voltage terminal Vbe is the base-emitter voltage of the transistor PNP, and the voltage of the voltage terminal Vbe is inversely proportional to the temperature value inside the chip.
4. The LED constant current controller with over-temperature regulation according to claim 2; characterized in that: The capacitor C2 and the resistor R3 are externally arranged outside the chip, the capacitor C2 is an adjustable capacitor, and the resistor R3 is an adjustable resistor.
5. The LED constant current controller with over-temperature regulation according to claim 1; characterized in that: The capacitance adjustment circuit includes a resistor R3, a first comparator CMP1, an NMOS tube N2 and a capacitor C2; wherein a reference voltage Vref is connected to the positive input terminal of the first comparator CMP1 and one end of the resistor R3, the negative end of the first comparator CMP1 is connected to the voltage terminal Vbe, the output of the first comparator CMP1 is connected to the gate of the NMOS tube N2, the source of the NMOS tube N2 is connected to one end of the capacitor C2, and the other end of the resistor R3 and the other end of the capacitor C2 are connected to the ground terminal GND.
6. The LED constant current controller with over-temperature regulation according to claim 1, characterized in that: The NMOS tube N3, the NMOS tube N4 or the NMOS tube N5 is an NPN tube.
7. The LED constant current controller with over-temperature regulation according to claim 5, characterized in that: The NMOS tube N2 is an NPN tube.
8. The LED constant current controller with over-temperature regulation according to claim 2, characterized in that: The NMOS tube N1 or the NMOS tube N2 is an NPN tube.