Inductive control non-isolated constant current circuit

Abstract

The utility model relates to an inductive control non-isolated constant current circuit which comprises an input protection rectification circuit, a filter circuit, an induction module power supply circuit, a PWM control circuit, a step-down constant current control circuit and an output filter circuit. The input protection rectification circuit converts commercial power into direct current and generates direct current bus voltage through the filter circuit. The induction module power supply circuit takes electricity from the direct current bus and provides a low-voltage power supply for the induction module. A PWM signal output by the induction module is converted into a threshold voltage signal of an ROVP pin of the constant-current control chip through the PWM control circuit, and a light source is controlled to start and stop through voltage comparison; the step-down constant-current control chip drives the light source to be on and off. According to the scheme, a non-isolated framework is adopted, and through voltage division power supply and a PWM-ROVP signal conversion mechanism, an independent power supply chip and a complex control circuit are omitted, the structural layout is simplified, the number of elements and the production cost are reduced, and the lamp size is reduced.

Description

An inductively controlled non-isolated constant current circuit Technical Field

[0001] This utility model relates to the field of lighting technology, and in particular to a non-isolated constant current circuit for induction control. Background Technology

[0002] Existing radar-controlled lighting systems typically use a constant current buck converter chip with PWM dimming function and an additional power supply chip to power the radar module. While this design enables intelligent control of the lighting fixtures, it has the following drawbacks:

[0003] High cost: Traditional designs require two separate chips to power the light source load and the radar module respectively. The additional power management chip not only increases the direct material cost, but also requires a more complex circuit board design, thereby increasing the cost of the PCB (printed circuit board).

[0004] The circuit structure is complex: to support the functions of two chips, more passive components need to be added to ensure the stability of voltage conversion and the accuracy of signal processing. However, each additional component or chip adds a potential point of failure; if a critical component fails, it may cause the entire system to malfunction.

[0005] Large lamp size: Due to the need to house multiple chips and related components, the overall size of the lamp has to be increased, which is a limiting factor for some applications, especially those with strict space requirements, such as smart homes or compact lighting equipment. At the same time, the larger lamp size may restrict its installation in certain locations, affecting the user experience. Summary of the Invention

[0006] The main purpose of this invention is to propose an inductive control non-isolated constant current circuit, which aims to solve the technical problems of high cost, complex circuit structure and large size of existing radar-controlled lighting systems.

[0007] To achieve the above objectives, this utility model proposes an inductive control non-isolated constant current circuit, including an input protection rectifier circuit, a filter circuit, an induction module, an induction module power supply circuit, a PWM control circuit, a step-down constant current control circuit, and an output filter circuit. The input of the input protection rectifier circuit is connected to AC power, and its output output is DC power. The input of the filter circuit is connected to the output of the input protection rectifier circuit, used to suppress high-frequency harmonics and generate a DC bus voltage. The input of the induction module power supply circuit is connected to the output of the filter circuit, and its output is connected to the power input of the induction module, used to provide low-voltage DC power to the induction module. The induction module is used for detection... The system measures the activity and generates a PWM signal; the PWM control circuit converts the PWM signal into a voltage signal at the ROVP pin of the constant current control chip; the step-down constant current control circuit includes a constant current control chip IC1, whose HV pin is connected to the output of the filter circuit to obtain the DC bus voltage, and whose output is used to connect to a light source to provide constant current drive; the ROVP pin is connected to the PWM control circuit, and the light source is controlled to start and stop by comparing the ROVP pin voltage signal with an internal threshold; the output filter circuit is connected between the output of the filter circuit and the output of the step-down constant current control circuit to suppress high-frequency noise and maintain stable output current.

[0008] Preferably, the input protection rectifier circuit includes a fuse F1, a safety capacitor CX1, and a rectifier bridge DB1; one end of the fuse F1 is configured to be connected to the live wire L of the AC mains input, and the other end is connected to the AC input terminal of the rectifier bridge DB1 and one end of the safety capacitor CX1, the other end of the safety capacitor CX1 is connected to the other AC input terminal of the rectifier bridge DB1, and the rectifier bridge DB1 outputs DC power through the DC output terminal.

[0009] Preferably, the filter circuit includes an I-shaped inductor L3, an electrolytic capacitor EC1, an electrolytic capacitor EC2, and a resistor R9; the I-shaped inductor L3 is connected in series with the positive terminal of the output of the input protection rectifier circuit; the positive terminal of the electrolytic capacitor EC1 is connected to the output of the I-shaped inductor L3, and the negative terminal is connected to the negative terminal of the output of the input protection rectifier circuit; the positive terminal of the electrolytic capacitor EC2 is connected to the input of the I-shaped inductor L3, and the negative terminal is connected to the negative terminal of the output of the input protection rectifier circuit; one end of the resistor R9 is connected to the input of the I-shaped inductor L3, and the other end is connected to the output of the I-shaped inductor L3.

[0010] Preferably, the power supply circuit of the sensing module includes a voltage divider circuit, a Zener diode D2, and an electrolytic capacitor EC3; the input terminal of the voltage divider circuit is connected to the positive terminal of the output terminal of the filter circuit, and the output terminal is connected to the power input terminal of the sensing module; the negative terminal of the Zener diode D2 is connected to the output terminal of the voltage divider circuit, and the positive terminal is connected to the negative terminal of the output terminal of the filter circuit; the positive terminal of the electrolytic capacitor EC3 is connected to the power input terminal of the sensing module, and the negative terminal is connected to the ground terminal of the sensing module.

[0011] Preferably, the voltage divider circuit includes a first voltage divider branch composed of resistors R4 and R5 connected in parallel, and a second voltage divider branch composed of resistors R2 and R3 connected in parallel; the input terminal of the first voltage divider branch is connected to the positive terminal of the output terminal of the filter circuit, the output terminal is connected to the input terminal of the second voltage divider branch, and the output terminal of the second voltage divider branch is connected to the power input terminal of the sensing module.

[0012] Preferably, the step-down constant current control circuit further includes a power inductor L4, a filter protection capacitor C1, and a CS sampling circuit; one end of the filter protection capacitor C1 is connected to the negative terminal of the output of the filter circuit, and the other end is used to connect to the negative terminal of the light source load; one end of the CS sampling circuit is connected to the CS pin of the constant current control chip IC1, and the other end is connected to the negative terminal of the output of the filter circuit; one end of the power inductor L4 is connected to the DRAIN pin of the constant current control chip IC1, and the other end is used to connect to the negative terminal of the light source load.

[0013] Preferably, the CS sampling circuit includes resistors RS1 and RS2 connected in parallel; one end of resistor RS1 is connected to the CS pin of the constant current control chip IC1, and the other end is connected to the negative output terminal of the filter circuit; one end of resistor RS2 is connected to the CS pin of the constant current control chip IC1, and the other end is connected to the negative output terminal of the filter circuit.

[0014] Preferably, the PWM control circuit includes a diode D1 and a resistor R1; the positive terminal of the diode D1 is connected to the PWM pin of the sensing module, and the negative terminal is connected to the ROVP pin of the constant current control chip IC1; one end of the resistor R1 is connected to the negative terminal of the diode D1, and the other end is connected to the negative terminal of the output of the filter circuit.

[0015] Preferably, the output filter circuit includes an electrolytic capacitor EC4 and a resistor R6; the positive terminal of the electrolytic capacitor EC4 is connected to the positive terminal of the output of the filter circuit, and the negative terminal is connected to the output of the step-down constant current control circuit; the resistor R6 is connected in parallel between the positive and negative terminals of the electrolytic capacitor EC4.

[0016] Preferably, the sensing module includes at least one of a microwave radar sensing module, an infrared sensing module, an ultrasonic sensing module, a light sensing module, and a sound sensing module, used to detect environmental changes and generate corresponding PWM signals.

[0017] This invention proposes a non-isolated constant current circuit for induction control. It provides a stable low-voltage power supply to the sensing module using a single constant current control chip IC1 combined with a voltage divider circuit and a Zener diode, replacing the traditional dual-chip solution. This reduces the need for additional power management chips, directly lowering material costs and simplifying PCB design complexity. When the sensing module detects human activity, it generates a PWM signal. The PWM control circuit converts this signal into a voltage signal at the ROVP pin of the constant current control chip. The constant current control chip controls the light source's on / off state by comparing the ROVP pin voltage signal with an internal threshold, providing a reliable overload protection mechanism and improving system stability and safety. The optimized circuit layout reduces the number of electronic components, lowering the risk of failure, while also reducing the overall size of the luminaire, enhancing installation flexibility and user experience. Furthermore, this invention achieves voltage regulation for the power supply of the sensing module in a non-isolated architecture through the synergy of a voltage divider circuit and a Zener diode, improving conversion efficiency while reducing standby power consumption. The π-type filter network, employing a multi-stage capacitor and inductor combination design, effectively suppresses input ripple and eliminates high-frequency noise interference, ensuring the detection sensitivity of the radar module. The CS sampling circuit enhances current sampling reliability through redundant layout, maintaining basic system functions even in the event of component failure, thus strengthening resilience in harsh environments. The PWM control circuit utilizes the unidirectional conduction characteristics of diodes and the potential-locked mechanism of pull-down resistors to ensure signal triggering accuracy and high-voltage isolation safety. The output filter circuit effectively stabilizes the drive current and eliminates turn-off ghosting through the synergy of dynamic energy storage and active discharge. In addition, the modular architecture supports plug-and-play and composite detection strategies for various sensor types, adaptively adjusting the detection mode according to scenario requirements. Combined with the linear response characteristics of the ROVP pin, it can also be expanded with intelligent dimming and multi-channel control functions. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 is a schematic diagram of the circuit principle of the induction control non-isolated constant current circuit provided in a specific embodiment of the present invention;

[0020] Figure 2 is a circuit diagram of a non-isolated constant current circuit for induction control provided in a specific embodiment of this utility model;

[0021] Figure 3 is a schematic diagram showing the module and circuit comparison of the induction control non-isolated constant current circuit provided in a specific embodiment of this utility model.

[0022] In the attached diagram: 1. Input protection rectifier circuit; 2. Filter circuit; 3. Sensing module; 4. Sensing module power supply circuit; 5. PWM control circuit; 6. Buck constant current control circuit; 7. Output filter circuit; 6.1. Constant current control chip; 6.2. CS sampling circuit.

[0023] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0025] It should be noted that if the embodiments of this utility model involve directional indicators, such as up, down, left, right, front, back, etc., the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0026] Furthermore, if the embodiments of this utility model involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this utility model.

[0027] As shown in Figures 1 to 3, this utility model proposes an inductive control non-isolated constant current circuit, including an input protection rectifier circuit 1, a filter circuit 2, an induction module 3, an induction module power supply circuit 4, a PWM control circuit 5, a step-down constant current control circuit 6, and an output filter circuit 7. The input terminal of the input protection rectifier circuit 1 is connected to AC power, and the output terminal outputs DC power. The input terminal of the filter circuit 2 is connected to the output terminal of the input protection rectifier circuit 1, used to suppress high-frequency harmonics and generate a DC bus voltage. The input terminal of the induction module power supply circuit 4 is connected to the output terminal of the filter circuit 2, and the output terminal is connected to the power input terminal of the induction module 3, used to provide low-voltage DC power to the induction module 3. 3 is used to detect activity and generate a PWM signal; the PWM control circuit 5 converts the PWM signal into a constant current control chip ROVP pin voltage signal; the step-down constant current control circuit 6 includes a constant current control chip IC1, the HV pin of the constant current control chip IC1 is connected to the output terminal of the filter circuit 2 to obtain the DC bus voltage, the output terminal is used to connect to the light source to provide constant current drive, the ROVP pin is connected to the PWM control circuit 5, and the light source is controlled to start and stop by comparing the ROVP pin voltage signal with an internal threshold; the output filter circuit 7 is connected between the output terminal of the filter circuit 2 and the output terminal of the step-down constant current control circuit 6 to suppress high-frequency noise and maintain stable output current.

[0028] In some embodiments, the input terminal of the input protection rectifier circuit 1 is connected to 220V AC mains power, which is converted into DC power. This DC power is then filtered by the filter circuit 2 for high-frequency harmonic suppression and voltage smoothing, and then split into two paths. The first path connects to the HV pin of the step-down constant current circuit 6 to provide a high-voltage DC input, utilizing the chip's internal high-voltage startup circuit for self-powering. The second path connects to the induction module power supply circuit 4 to convert the DC power to a low-voltage DC, reducing the voltage to the operating voltage of the induction module 3 (e.g., 12V / 5V / 3.3V), providing continuous power to the induction module 3. The PWM control circuit 5 converts the PWM signal from the induction module 3 into a linear voltage signal and connects it to the ROVP pin of the constant current control chip IC1. When the induction module 3 detects activity, its PWM output terminal continuously outputs a PWM signal, which is then processed by the filter circuit 2. The PWM control circuit 5 converts the signal into a stable voltage signal higher than the chip's internal threshold (e.g., the voltage threshold of the chip's ROVP pin is 0.3V). When the constant current control chip IC1 detects that the ROVP pin voltage exceeds the chip's internal threshold, it controls the light source to start. During continuous human activity, the sensing module 3 maintains the output PWM signal to keep the ROVP voltage stable above the threshold. When the sensing module 3 detects that a person has left the detection area, after a preset departure time threshold (e.g., 30 seconds after the last detected activity), it adjusts the output PWM signal so that the voltage signal after the PWM control circuit 5 is lower than the chip's internal threshold (e.g., the ROVP voltage threshold is 0.3V). When the constant current control chip IC1 detects that the ROVP pin voltage is lower than the chip's internal threshold, it controls the light source to turn off. It is understandable that this embodiment utilizes the sensing module's power supply circuit to directly draw power from the DC bus and step down the voltage, eliminating the need for a separate power management chip in traditional solutions. This reduces a large number of components, lowers production and integration costs, reduces the circuit board wiring area, and improves circuit stability.

[0029] Preferably, in one embodiment of this application, the input protection rectifier circuit 1 includes a fuse F1, a safety capacitor CX1, and a rectifier bridge DB1; one end of the fuse F1 is configured to be connected to the live wire L of the mains input, and the other end is connected to the AC input terminal of the rectifier bridge DB1 and one end of the safety capacitor CX1, the other end of the safety capacitor CX1 is connected to the other AC input terminal of the rectifier bridge DB1, and the rectifier bridge DB1 outputs DC power through the DC output terminal.

[0030] Understandably, fuse F1 will blow when the input current is abnormal. Combined with the voltage-resistance redundancy design of safety capacitor CX1, it can still maintain safe isolation when the circuit encounters lightning surges. This utility model is a non-isolated architecture without an isolation transformer. The rectifier bridge DB1 can ensure the basic insulation strength between the primary and secondary sides. In this embodiment, the rectifier bridge DB1 uses an MB10F type rectifier bridge to convert 220V AC to DC. Those skilled in the art can also choose other input protection rectifier circuit designs according to specific application requirements: in terms of rectifier bridge selection, a surface-mount rectifier bridge can be used to adapt to a compact PCB layout, or a high-power rectifier bridge can be used to match high-current application scenarios; in terms of overvoltage protection, a varistor can be connected in parallel at the AC input terminal of rectifier bridge DB1 to absorb transient overvoltages caused by lightning strikes; for cold start surge suppression, an NTC thermistor can be connected in series after fuse F1 to limit the start-up inrush current.

[0031] Preferably, in one embodiment of this application, the filter circuit 2 includes an I-shaped inductor L3, an electrolytic capacitor EC1, an electrolytic capacitor EC2, and a resistor R9; the I-shaped inductor L3 is connected in series with the positive terminal of the output terminal of the input protection rectifier circuit 1; the positive terminal of the electrolytic capacitor EC1 is connected to the output terminal of the I-shaped inductor L3, and the negative terminal is connected to the negative terminal of the output terminal of the input protection rectifier circuit 1; the positive terminal of the electrolytic capacitor EC2 is connected to the input terminal of the I-shaped inductor L3, and the negative terminal is connected to the negative terminal of the output terminal of the input protection rectifier circuit 1; one end of the resistor R9 is connected to the input terminal of the I-shaped inductor L3, and the other end is connected to the output terminal of the I-shaped inductor L3.

[0032] Understandably, the I-type inductor L3, together with electrolytic capacitors EC1 and EC2, forms a π-type filter network. The hysteresis loss characteristics of the I-type inductor suppress high-frequency conducted interference. Electrolytic capacitors EC1 and EC2 perform two-stage energy storage filtering on the rectified pulsating DC. EC2 focuses on absorbing the low-frequency ripple output of the rectifier bridge DB1, while EC1 performs secondary filtering on the high-frequency switching noise at the back end of the I-type inductor L3. Resistor R9 is connected across the two sides of the I-type inductor to form a charge discharge circuit, which can eliminate voltage spikes caused by inductor energy storage and balance the potential difference between the inductor input and output terminals to prevent core saturation. Those skilled in the art can also choose other filter circuit designs according to specific application requirements: such as L-type filter circuit, which uses an inductor and an electrolytic capacitor connected in series at the positive terminal of the DC bus, suppressing high-frequency ripple through the energy storage characteristics of the inductor, suitable for compact designs that are sensitive to size; CLC composite filter circuit, which first connects a thin film capacitor to the output of the rectifier bridge to absorb high-frequency noise, and then connects a toroidal inductor and an electrolytic capacitor in cascade to form a three-stage filter network, suitable for high-power LED driving scenarios; multi-stage LC filter circuit, which sets two-stage LC filters on the DC bus, the first stage uses an I-shaped inductor connected in parallel with a ceramic capacitor, and the second stage uses a combination of a magnetically shielded inductor and an electrolytic capacitor, which can effectively separate low-frequency and high-frequency interference bands; RC buffer filter circuit, which connects a resistor and a capacitor in series in parallel at the output of the rectifier bridge, suppressing resonance spikes through the damping characteristics of the resistor, suitable for scenarios where switching power supplies are frequently started and stopped.

[0033] Preferably, in one embodiment of this application, the power supply circuit 4 of the sensing module includes a voltage divider circuit, a Zener diode D2, and an electrolytic capacitor EC3; the input terminal of the voltage divider circuit is connected to the positive terminal of the output terminal of the filter circuit 2, and the output terminal is connected to the power input terminal of the sensing module 3; the negative terminal of the Zener diode D2 is connected to the output terminal of the voltage divider circuit, and the positive terminal is connected to the negative terminal of the output terminal of the filter circuit 2; the positive terminal of the electrolytic capacitor EC3 is connected to the power input terminal of the sensing module 3, and the negative terminal is connected to the ground terminal of the sensing module 3.

[0034] Understandably, the voltage divider circuit, composed of a resistor network, is used to convert the high-voltage DC power obtained from the DC bus voltage into the low-voltage DC power required for the induction module's operating voltage. For ease of understanding, an example is given below. In this embodiment, the 220V AC input, after passing through the protection rectifier and filter circuits, yields a DC bus voltage of 310V. The induction module's operating voltage is 3.3V. The voltage divider circuit, through the resistor network, reduces the 310V high voltage from the DC bus to the 3.3V low voltage required by the induction module. The Zener diode D2 is selected with a nominal Zener diode value of 3.3V. Its positive terminal is connected to the output terminal of the voltage divider circuit and also to the positive terminal of the filter circuit 2's output. When the voltage output by the voltage divider circuit exceeds 3.3V, D2 immediately conducts and... The voltage is limited to 3.3V. Even if a lightning surge causes a momentary spike in the input voltage, the output voltage can still be maintained at no higher than 3.6V through the avalanche effect of D2. The electrolytic capacitor EC3 suppresses voltage ripple and filters high-frequency noise, reducing the 3.3V voltage ripple after conversion from the 310V DC bus from ±200mV to within ±30mV, ensuring stable operation of the sensing module's RF circuit. It also provides instantaneous power-off protection; when the mains power is momentarily interrupted, the radar module can complete the final action signal transmission (such as sending a "turn off the lights" command), preventing malfunctions of the lights or communication interruptions. Those skilled in the art can also choose other sensing module power supply circuit designs according to specific application requirements, such as adding an LDO low-dropout linear regulator at the output of the voltage divider circuit, adjusting the output voltage to 3.3V through internal chip feedback. Such equivalent designs are all within the protection scope of the claims of this utility model.

[0035] Preferably, in one embodiment of this application, the voltage divider circuit includes a first voltage divider branch composed of resistors R4 and R5 connected in parallel, and a second voltage divider branch composed of resistors R2 and R3 connected in parallel; the input terminal of the first voltage divider branch is connected to the positive terminal of the output terminal of the filter circuit 2, the output terminal is connected to the input terminal of the second voltage divider branch, and the output terminal of the second voltage divider branch is connected to the power input terminal of the sensing module 3.

[0036] Understandably, the first voltage divider branch achieves high resistance characteristics through the parallel combination of resistors R4 and R5, reducing quiescent current while increasing power carrying capacity; the second voltage divider branch uses relatively low resistance values ​​for resistors R2 and R3 to enhance the anti-interference capability of the voltage divider node. The two voltage divider branches are connected in series to form a stepped attenuation structure, converting the high voltage of the DC bus to a low voltage suitable for the induction module's operation by appropriately setting the voltage division ratio. The parallel design of the first voltage divider branch disperses power loss and avoids single-point failure through redundant configuration, while the second voltage divider branch suppresses high-frequency noise through its low resistance characteristics. Those skilled in the art can adjust the number of voltage divider stages or the resistor topology according to actual needs, for example, using a three-stage voltage divider to improve accuracy, or adding high-frequency filter capacitors between voltage divider nodes; such equivalent designs are all within the protection scope of the claims of this utility model.

[0037] Preferably, in one embodiment of this application, the step-down constant current control circuit 6 further includes a power inductor L4, a filter protection capacitor C1, and a CS sampling circuit; one end of the filter protection capacitor C1 is connected to the negative terminal of the output of the filter circuit 2, and the other end is used to connect to the negative terminal of the light source load; one end of the CS sampling circuit is connected to the CS pin of the constant current control chip IC1, and the other end is connected to the negative terminal of the output of the filter circuit 2; one end of the power inductor L4 is connected to the DRAIN pin of the constant current control chip IC1, and the other end is used to connect to the negative terminal of the light source load.

[0038] Understandably, the CS sampling circuit acquires the load current signal in real time and feeds it back to the CS pin of the constant current control chip IC1. After comparing it with the internal reference voltage of the chip, it dynamically adjusts the switching duty cycle to ensure that the output current is stable at the set value. The power inductor L4 works in conjunction with the internal switching transistor of the constant current control chip IC1 to achieve voltage reduction conversion during the chip's switching operation, converting the high voltage of the DC bus into a low voltage suitable for the light source's operation. The filter protection capacitor C1 is connected across the load circuit, which can absorb high-frequency switching noise and suppress voltage surges, preventing the light source from being subjected to voltage spikes. In this embodiment, pins 5 and 6 of the constant current control chip IC1 are both DRAIN pins. One end of the power inductor L4 is connected to both of these pins. The parallel structure of the dual DRAIN pins can evenly distribute the switching current of the transistor to the two pins, effectively reducing the current density of a single pin and reducing the pin temperature rise compared to the single-pin solution, thereby improving the long-term reliability of the chip. When one DRAIN pin is damaged due to overcurrent, the other pin can still maintain 50% load capacity, and the system enters a derating operation state instead of complete failure, effectively improving the reliability of the light source illumination. Those skilled in the art can adjust the circuit parameters according to the actual application scenario. For example, a multi-stage LC filter can be used to replace a single capacitor filter, or a differential amplifier circuit can be added to the sampling circuit to improve the detection accuracy, or a single DRAIN pin can be used to connect to L4. Such equivalent improvement schemes all fall within the protection scope of the claims of this utility model.

[0039] Preferably, in one embodiment of this application, the CS sampling circuit includes resistors RS1 and RS2 connected in parallel; one end of resistor RS1 is connected to the CS pin of the constant current control chip IC1, and the other end is connected to the negative output terminal of the filter circuit 2; one end of resistor RS2 is connected to the CS pin of the constant current control chip IC1, and the other end is connected to the negative output terminal of the filter circuit 2.

[0040] Understandably, the parallel design of the dual resistors evenly distributes the power loss generated by current sampling across RS1 and RS2, effectively reducing the heat accumulation rate and avoiding sampling errors caused by temperature drift. Simultaneously, resistors RS1 and RS2 serve as backups for each other; if either resistor fails open-circuit, the other can still maintain the sampling function. In extreme conditions (such as lightning surges), even if one resistor breaks down and short-circuits, the system can still perform overcurrent protection through the remaining resistor, improving sampling accuracy under fault conditions. Those skilled in the art can adjust the number or parameters of the parallel resistors according to actual needs. For example, using three resistors in parallel can improve power redundancy, or adding an RC filter network to the sampling circuit can optimize signal integrity. Such equivalent improvements fall within the scope of protection of the claims of this utility model. The CS sampling circuit design of this utility model achieves a comprehensive improvement in reliability, thermal performance, and anti-interference capability while ensuring sampling accuracy.

[0041] Preferably, in one embodiment of this application, the PWM control circuit 5 includes a diode D1 and a resistor R1; the positive terminal of the diode D1 is connected to the PWM pin of the sensing module 3, and the negative terminal is connected to the ROVP pin of the constant current control chip IC1; one end of the resistor R1 is connected to the negative terminal of the diode D1, and the other end is connected to the negative terminal of the output of the filter circuit 2.

[0042] Understandably, this invention connects the positive terminal of diode D1 to the PWM output terminal of the sensing module, utilizing its unidirectional conduction characteristic to achieve signal isolation, ensuring that the PWM signal can only be transmitted unidirectionally from the sensing module to the ROVP pin, blocking the reverse coupling of the ROVP pin voltage to the sensing module; the resistor R1 is a pull-down resistor. When the sensing module does not detect activity, the PWM output terminal remains at a low level (0V), and diode D1 is cut off. At this time, the pull-down resistor R1 pulls the ROVP pin voltage down to below the chip's internal threshold of 0.3V, triggering the constant current control chip IC1 to enter the protection disabled state, and the chip controls the light source to turn off; when the sensing module detects activity, the PWM output terminal sends a high-level signal, and after D1 is turned on, the ROVP pin voltage rises. The constant current control chip IC1 detects that the ROVP pin voltage is greater than the internal threshold of 0.3V and then exits the protection state, and the chip controls the light source to light up. Those skilled in the art can make equivalent improvements according to actual needs. For example, they can adjust the amplitude of the PWM signal by connecting a current-limiting resistor in series with the negative terminal of diode D1 to adapt to the threshold voltage requirements of different chips, or use an optocoupler to replace diode D1 to achieve electrical isolation between the sensing module and the high-voltage side, or add a filter capacitor between the ROVP pin and the negative terminal to optimize the high-frequency noise suppression characteristics, or replace the pull-down resistor R1 with an adjustable resistor network to adjust the threshold voltage. Such equivalent improvements are all within the protection scope of the claims of this utility model.

[0043] Preferably, in one embodiment of this application, the output filter circuit 7 includes an electrolytic capacitor EC4 and a resistor R6; the positive terminal of the electrolytic capacitor EC4 is connected to the positive terminal of the output of the filter circuit 2, and the negative terminal is connected to the output of the step-down constant current control circuit 6; the resistor R6 is connected in parallel between the positive and negative terminals of the electrolytic capacitor EC4.

[0044] Understandably, the electrolytic capacitor EC4 is connected across the positive terminal of the output of the filter circuit (2) and the output of the step-down constant current control circuit (6). The positive terminal of the DC bus voltage of the filter circuit (2) is connected to the positive terminal LED+ of the light source load. The output terminal (IC1 switch output terminal) of the step-down constant current control circuit (6) is connected to the negative terminal LED- of the light source load through the power inductor L4. When the internal switch of the constant current control chip IC1 is turned on, the current path is: positive terminal of the output of the filter circuit 2 → positive terminal LED+ of the light source load → light source load → negative terminal LED- of the light source load → power inductor L4 → constant current control chip IC1 → negative terminal of the output of the filter circuit 2. When the switch is turned off, the freewheeling current of the power inductor L4 forms a closed loop through the electrolytic capacitor EC4 to maintain the continuity of the load current. The electrolytic capacitor EC4 can absorb high-frequency ripple current (such as noise above 100kHz generated by a switching power supply) and provide instantaneous energy storage. When the load current changes abruptly, the electrolytic capacitor EC4 can release its stored charge to compensate for the current gap, avoiding flickering of the light source. The resistor R6 is connected in parallel across the capacitor to form an active discharge circuit. When the system is turned off, it can quickly discharge the residual charge of the electrolytic capacitor EC4, preventing residual capacitor voltage from causing dim or slow-burning light sources. Those skilled in the art can make equivalent improvements according to actual needs. For details, please refer to the design extension ideas of the aforementioned filter circuit. Technicians can choose the optimization direction based on cost, efficiency, size, etc., which will not be elaborated here.

[0045] Preferably, in one embodiment of this application, the sensing module 3 includes at least one of a microwave radar sensing module, an infrared sensing module, an ultrasonic sensing module, a light sensing module, and a sound sensing module, used to detect environmental changes and generate corresponding PWM signals.

[0046] Understandably, all sensing modules are equipped with standardized PWM interfaces, outputting PWM signals with adjustable duty cycles (e.g., 0-100% duty cycles correspond to different voltage levels) regardless of the detection mode. A unified signal format ensures compatibility with constant current control chips. The modules adopt a plug-in design, allowing users to freely select or combine sensor types according to their application scenarios: microwave radar sensing modules detect human movement through the Doppler effect and have high immunity to interference from inanimate objects (such as wind blowing curtains), making them suitable for scenarios such as corridors and restrooms; infrared sensing modules have continuous detection capabilities for stationary human bodies, suitable for environments requiring long-term lighting, such as office areas; ultrasonic sensing modules can penetrate transparent obstacles for detection, suitable for special installation scenarios such as cabinets and glass partitions; light sensing modules can detect light intensity, avoiding false triggering during the day; sound sensing modules identify specific sounds (such as clapping and footsteps) through sound signals, suitable for barrier-free control scenarios, enabling non-contact control through preset sound commands. Furthermore, this embodiment supports the collaborative operation of multiple types of sensing modules. For example, in medical settings, the microwave radar module detects the movement trajectory of personnel and then links with the infrared module to confirm the patient's stationary state before outputting a PWM dimming signal. In a warehouse environment, the ultrasonic module penetrates the shelves to detect the storage and retrieval of items, while the light sensing module dynamically adjusts the PWM signal based on the ambient illuminance. For accessible scenarios, after the sound module identifies specific voiceprint commands, the radar module verifies the personnel's location a second time, avoiding false triggering due to background noise. The sensing module 3 can be configured independently or in combination, allowing users to freely choose a single sensor or combine multiple sensors according to scenario requirements. Regardless of whether a single module (directly mapping the original signal) or a composite module (preset rule mapping processing) is used, the detection signals from each sensor are converted into composite PWM signals through a preset unified logic (such as weighted method, average method, or priority method) fusion engine, and finally output to the constant current control chip through a unified interface to achieve accurate matching of multi-dimensional lighting strategies. Those skilled in the art can adjust the module combination method or signal fusion algorithm according to actual needs. Such improvements, while maintaining the standardized interface and core composite detection functions, are all within the protection scope of the claims of this utility model.

[0047] Specifically, in one embodiment of this invention, the sensing module uses an EDC18F microwave radar sensing module with an operating frequency of 5.8GHz and a built-in photosensor unit. When human movement is detected, combined with the built-in photosensor data, a duty cycle gradient signal is output through the PWM interface when the ambient illuminance is below a preset threshold. This signal is then converted to a logic voltage via the PWM control circuit and transmitted to the ROVP pin of the constant current control chip IC1. Adjusting the voltage at the ROVP pin gradually brightens and dims the LED light. Those skilled in the art can also select other models of microwave radar sensors, such as the EDC15 and EDC19 series, according to specific application requirements. These sensors also possess high-frequency operation and strong anti-interference performance, making them suitable for various lighting control scenarios.

[0048] The above description is only a preferred embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present utility model.

Claims

1. A non-isolated constant current circuit with inductive control, characterized in that, include: The circuit comprises an input protection rectifier circuit (1), a filter circuit (2), an induction module (3), an induction module power supply circuit (4), a PWM control circuit (5), a step-down constant current control circuit (6), and an output filter circuit (7). The input of the input protection rectifier circuit (1) is connected to the mains power, and the output of the filter circuit (2) is DC power. The input of the filter circuit (2) is connected to the output of the input protection rectifier circuit (1) to suppress high-frequency harmonics and generate DC bus voltage. The input of the induction module power supply circuit (4) is connected to the output of the filter circuit (2), and the output is connected to the power input of the induction module (3) to provide low-voltage DC power to the induction module (3). The induction module (3) is used to detect activity and... A PWM signal is generated; the PWM control circuit (5) converts the PWM signal into a voltage signal at the ROVP pin of the constant current control chip; the step-down constant current control circuit (6) includes a constant current control chip IC1, the HV pin of the constant current control chip IC1 is connected to the output terminal of the filter circuit (2) to obtain the DC bus voltage, the output terminal is used to connect the light source to provide constant current drive, the ROVP pin is connected to the PWM control circuit (5), and the light source is controlled to start and stop by comparing the ROVP pin voltage signal with the internal threshold; the output filter circuit (7) is connected between the output terminal of the filter circuit (2) and the output terminal of the step-down constant current control circuit (6) to suppress high-frequency noise and maintain stable output current.

2. The inductively controlled non-isolated constant current circuit as described in claim 1, characterized in that, The input protection rectifier circuit (1) includes a fuse F1, a safety capacitor CX1, and a rectifier bridge DB1. One end of the fuse F1 is configured to be connected to the live wire L of the mains input, and the other end is connected to the AC input terminal of the rectifier bridge DB1 and one end of the safety capacitor CX1. The other end of the safety capacitor CX1 is connected to the other AC input terminal of the rectifier bridge DB1. The rectifier bridge DB1 outputs DC power through the DC output terminal.

3. The inductively controlled non-isolated constant current circuit as described in claim 1, characterized in that, The filter circuit (2) includes an I-shaped inductor L3, an electrolytic capacitor EC1, an electrolytic capacitor EC2, and a resistor R9. The I-shaped inductor L3 is connected in series with the positive terminal of the output terminal of the input protection rectifier circuit (1). The positive terminal of the electrolytic capacitor EC1 is connected to the output terminal of the I-shaped inductor L3, and the negative terminal is connected to the negative terminal of the output terminal of the input protection rectifier circuit (1). The positive terminal of the electrolytic capacitor EC2 is connected to the input terminal of the I-shaped inductor L3, and the negative terminal is connected to the negative terminal of the output terminal of the input protection rectifier circuit (1). One end of the resistor R9 is connected to the input terminal of the I-shaped inductor L3, and the other end is connected to the output terminal of the I-shaped inductor L3.

4. The inductively controlled non-isolated constant current circuit as described in claim 1, characterized in that, The power supply circuit (4) of the sensing module includes a voltage divider circuit, a Zener diode D2, and an electrolytic capacitor EC3; the input terminal of the voltage divider circuit is connected to the positive terminal of the output terminal of the filter circuit (2), and the output terminal is connected to the power input terminal of the sensing module (3); the negative terminal of the Zener diode D2 is connected to the output terminal of the voltage divider circuit, and the positive terminal is connected to the negative terminal of the output terminal of the filter circuit (2); the positive terminal of the electrolytic capacitor EC3 is connected to the power input terminal of the sensing module (3), and the negative terminal is connected to the ground terminal of the sensing module (3).

5. The inductively controlled non-isolated constant current circuit as described in claim 4, characterized in that, The voltage divider circuit includes a first voltage divider branch consisting of resistors R4 and R5 connected in parallel, and a second voltage divider branch consisting of resistors R2 and R3 connected in parallel; the input terminal of the first voltage divider branch is connected to the positive terminal of the output terminal of the filter circuit (2), the output terminal is connected to the input terminal of the second voltage divider branch, and the output terminal of the second voltage divider branch is connected to the power input terminal of the sensing module (3).

6. The inductively controlled non-isolated constant current circuit as described in claim 1, characterized in that, The step-down constant current control circuit (6) also includes a power inductor L4, a filter protection capacitor C1, and a CS sampling circuit; one end of the filter protection capacitor C1 is connected to the negative terminal of the output of the filter circuit (2), and the other end is used to connect to the negative terminal of the light source load; one end of the CS sampling circuit is connected to the CS pin of the constant current control chip IC1, and the other end is connected to the negative terminal of the output of the filter circuit (2); one end of the power inductor L4 is connected to the DRAIN pin of the constant current control chip IC1, and the other end is used to connect to the negative terminal of the light source load.

7. The inductively controlled non-isolated constant current circuit as described in claim 6, characterized in that, The CS sampling circuit includes resistors RS1 and RS2 connected in parallel; one end of resistor RS1 is connected to the CS pin of the constant current control chip IC1, and the other end is connected to the negative output terminal of the filter circuit (2); one end of resistor RS2 is connected to the CS pin of the constant current control chip IC1, and the other end is connected to the negative output terminal of the filter circuit (2).

8. The inductively controlled non-isolated constant current circuit as described in claim 1, characterized in that, The PWM control circuit (5) includes a diode D1 and a resistor R1; the positive terminal of the diode D1 is connected to the PWM pin of the sensing module (3), and the negative terminal is connected to the ROVP pin of the constant current control chip IC1; one end of the resistor R1 is connected to the negative terminal of the diode D1, and the other end is connected to the negative terminal of the output of the filter circuit (2).

9. The inductively controlled non-isolated constant current circuit as described in claim 1, characterized in that, The output filter circuit (7) includes an electrolytic capacitor EC4 and a resistor R6; the positive terminal of the electrolytic capacitor EC4 is connected to the positive terminal of the output of the filter circuit (2), and the negative terminal is connected to the output of the step-down constant current control circuit (6); the resistor R6 is connected in parallel between the positive and negative terminals of the electrolytic capacitor EC4.

10. The inductively controlled non-isolated constant current circuit as described in claim 1, characterized in that, The sensing module (3) includes at least one of a microwave radar sensing module, an infrared sensing module, an ultrasonic sensing module, a light sensing module, and a sound sensing module, and is used to detect environmental changes and generate corresponding PWM signals.

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