LED control circuit

Abstract

According to the LED control circuit, isolation of a control signal and a power signal is achieved through an optical coupler, the safety and stability of the circuit are improved, when the control signal is at a low level, an LED and a photo-transistor in the optical coupler are conducted, so that a grid electrode of an MOSFET obtains a driving voltage to be conducted, finally current is allowed to pass through the LED, the LED is lightened, and the LED is prevented from being damaged. The technical problems that a direct logic level control method may have potential safety hazards in a high-voltage or high-current environment, and direct connection between different power supplies may introduce noise and interference to affect the stability and reliability of the circuit are solved.

Description

Technical Field

[0001] This application relates to the field of circuit design technology, and in particular to an LED control circuit. Background Technology

[0002] While direct logic level control is simple in traditional LED control circuits, it can pose safety hazards under high voltage or high current conditions. Furthermore, direct connections between different power supplies can introduce noise and interference, affecting the circuit's stability and reliability. Summary of the Invention

[0003] This application provides an LED control circuit that solves the technical problems that direct logic level control methods may pose safety hazards in high voltage or high current environments, and that direct connections between different power supplies may introduce noise and interference, affecting the stability and reliability of the circuit.

[0004] In view of this, this application provides an LED control circuit, the LED control circuit comprising:

[0005] Optocouplers, MOSFET control circuits, and LEDs;

[0006] The optocoupler is connected to the power supply, the control signal, and the MOSFET control circuit, respectively.

[0007] The MOSFET control circuit is connected to the LED via a current sensing resistor.

[0008] Optionally, the optocoupler includes four pins, wherein:

[0009] The first pin is connected to the first DC power supply via a first resistor (R26);

[0010] The second pin is connected to the control signal;

[0011] The third pin is connected to the gate of the MOSFET field-effect transistor (Q3) in the MOSFET control circuit;

[0012] The fourth pin is connected to the second DC power supply via the second resistor (R27).

[0013] Optionally, a bias resistor (R28) is connected in parallel between the gate of the MOSFET (Q3) and ground;

[0014] The drain of the MOSFET (Q3) is connected to the current sensing resistor (R25);

[0015] The source of the MOSFET (Q3) is grounded.

[0016] Optionally, a transient voltage suppressor (D19) is connected in parallel between the drain of the MOSFET (Q3) and ground.

[0017] Optionally, the anode of the LED is connected to the drain of the MOSFET (Q3) through a current sensing resistor (R25);

[0018] The cathode of the LED is connected to a third DC power supply via a third resistor (R29).

[0019] As can be seen from the above technical solutions, the embodiments of this application have the following advantages:

[0020] This application provides an LED control circuit that uses an optocoupler to isolate the control signal from the power signal, thereby improving the circuit's safety and stability. When the control signal is low, the LED and phototransistor inside the optocoupler are turned on, allowing the MOSFET gate to receive a driving voltage and thus conduct, ultimately enabling current to flow through the LED and lighting it up. This solves the technical problems that direct logic level control methods may pose safety hazards in high-voltage or high-current environments, and that direct connections between different power supplies may introduce noise and interference, affecting the stability and reliability of the circuit. Attached Figure Description

[0021] Figure 1 This is a circuit diagram of the LED control circuit in this application. Detailed Implementation

[0022] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present application.

[0023] This application designs an LED control circuit that solves the technical problems that direct logic level control methods may pose safety hazards in high voltage or high current environments, and that direct connection between different power supplies may introduce noise and interference, affecting the stability and reliability of the circuit.

[0024] For easier understanding, please refer to Figure 1 , Figure 1 This is a circuit structure diagram of the LED control circuit in an embodiment of this application, as shown below. Figure 1 As shown, it specifically includes:

[0025] Optocoupler U8, MOSFET control circuit and LED;

[0026] Optocoupler U8 is connected to the power supply, control signal, and MOSFET control circuit, respectively.

[0027] The MOSFET control circuit is connected to the LED via a current sensing resistor.

[0028] Furthermore, the optocoupler includes four pins, wherein:

[0029] The first pin is connected to the first DC power supply via the first resistor R26;

[0030] The second pin is connected to the control signal;

[0031] The third pin is connected to the gate of the MOSFET field-effect transistor Q3 in the MOSFET control circuit;

[0032] The fourth pin is connected to the second DC power supply via the second resistor R27.

[0033] It should be noted that an optocoupler is a semiconductor device that uses optical signals to control electrical signals. It typically consists of a light-emitting diode (LED) and a phototransistor (or photodiode). In this circuit, the optocoupler serves to isolate and control signal transmission.

[0034] The first pin is connected to the first DC power supply via the first resistor R26. This power supply provides voltage to the LED of the optocoupler, causing it to emit light.

[0035] The second pin connects to the control signal, which controls the on / off state of the LED inside the optocoupler, thereby controlling the conduction and cutoff of the phototransistor.

[0036] The third pin is connected to the gate of the MOSFET field-effect transistor Q3 in the MOSFET control circuit. The conduction and cutoff of the phototransistor will control the gate voltage of the MOSFET, thereby controlling the conduction and cutoff of the MOSFET.

[0037] Pin 4: Connected to the second DC power supply via the second resistor R27. This power supply provides voltage to the phototransistor inside the optocoupler.

[0038] Furthermore, a bias resistor R28 is connected in parallel between the gate of the MOSFET field-effect transistor Q3 and ground;

[0039] The drain of MOSFET Q3 is connected to the current sensing resistor R25;

[0040] The source of MOSFET Q3 is grounded.

[0041] Furthermore, a transient voltage suppressor D19 is connected in parallel between the drain of the MOSFET field-effect transistor Q3 and ground.

[0042] It should be noted that a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) is a voltage-controlled device that can control the current between the drain and source by changing the gate voltage.

[0043] Gate: Connected to the third pin of the optocoupler, the MOSFET is turned on and off by the control signal of the optocoupler.

[0044] Bias resistor R28 between gate and ground: This resistor is used to set the gate voltage, ensuring that the MOSFET is in a defined state when there is no control signal.

[0045] Drain: Connected to current sensing resistor R25, which is used to detect the current flowing through the MOSFET.

[0046] Source: Grounded, which is the reference point for the MOSFET.

[0047] D19, a transient voltage suppressor between drain and ground: This component is used to protect MOSFETs and LEDs from voltage spikes that could damage them.

[0048] Furthermore, the anode of the LED is connected to the drain of the MOSFET field-effect transistor Q3 through the current sensing resistor R25;

[0049] The cathode of the LED is connected to the third DC power supply via the third resistor R29.

[0050] It should be noted that an LED (light-emitting diode) is a semiconductor device that emits light when an electric current passes through it.

[0051] Anode: Connected to the drain of MOSFET Q3 via current sensing resistor R25, so that the brightness of the LED can be adjusted by controlling the conduction level of the MOSFET.

[0052] Cathode: Connected to a third DC power supply via a third resistor R29, which provides voltage to the LED.

[0053] Suppose we want to control the brightness of an LED. First, we control the on / off state of the LED inside the optocoupler by changing the control signal connected to the second pin of the optocoupler. The on / off state of the LED controls the conduction and cutoff of the phototransistor, which in turn changes the voltage at the MOSFET gate. When the MOSFET gate voltage changes, the MOSFET's conduction level also changes, which affects the current flowing through the current sensing resistor R25, thereby controlling the LED brightness.

[0054] When the MOSFET is fully turned on, current can flow freely, and the LED will be fully lit. When the MOSFET is turned off, current cannot flow, and the LED will be off. By adjusting the control signal, we can adjust the brightness of the LED between fully lit and off states.

[0055] The advantage of this circuit design lies in the electrical isolation provided by the use of optocouplers. This protects the control signals from power supply noise and also protects the control circuit from high voltage damage. Furthermore, the transient voltage suppressor D19 and bias resistor R28 provide additional protection, ensuring the stability and reliability of the circuit.

[0056] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. An LED control circuit, characterized in that, include: Optocouplers, MOSFET control circuits, and LEDs; The optocoupler is connected to the power supply, the control signal, and the MOSFET control circuit, respectively. The MOSFET control circuit is connected to the LED via a current sensing resistor.

2. The LED control circuit according to claim 1, characterized in that, The optocoupler includes four pins, wherein: The first pin is connected to the first DC power supply via a first resistor (R26); The second pin is connected to the control signal; The third pin is connected to the gate of the MOSFET field-effect transistor (Q3) in the MOSFET control circuit; The fourth pin is connected to the second DC power supply via the second resistor (R27).

3. The LED control circuit according to claim 2, characterized in that, A bias resistor (R28) is connected in parallel between the gate of the MOSFET (Q3) and ground; The drain of the MOSFET (Q3) is connected to the current sensing resistor (R25); The source of the MOSFET (Q3) is grounded.

4. The LED control circuit according to claim 3, characterized in that, A transient voltage suppressor (D19) is connected in parallel between the drain of the MOSFET (Q3) and ground.

5. The LED control circuit according to claim 3, characterized in that, The anode of the LED is connected to the drain of the MOSFET (Q3) through a current sensing resistor (R25); The cathode of the LED is connected to a third DC power supply via a third resistor (R29).

Images