**LED Lamp Drive Power Circuit Diagram (a) - Circuit Working Principle**
The circuit of the LED corridor light is shown below. It consists of a capacitor step-down circuit, a rectifier circuit, an LED lighting circuit, and a photoelectric control circuit. The 220V AC power is first stepped down through capacitor C1 and resistor R1 to reduce the current. After this, the AC voltage at points A and B is approximately 15V. This voltage is then rectified by VD1 to VD4, resulting in a DC voltage of about 14V on C2, which serves as the working voltage for high-brightness LEDs VD5 to VD8, with a current of around 14mA.
Since capacitor C1 does not consume active power, and the power consumed by the bleeder resistor is negligible, the overall power consumption of the circuit is roughly 15 × 0.014 ≈ 0.2W. To further save power and extend the lifespan of the high-brightness LEDs, a photoelectric control circuit is added, consisting of a photoresistor R2, a resistor R3, and a transistor VT1. At night, the resistance of R2 increases to over 100kΩ, causing a small DC bias voltage at the base of VT1, which keeps it off and has no impact on the LED operation. During the day, due to the photoelectric effect, the resistance of R2 drops below 10kΩ, turning on VT1 and allowing it to enter saturation. This causes the voltage on C2 to drop below 4V due to the shunting effect of VT1, effectively reducing the power used by the LEDs.
**LED Lamp Drive Power Supply Circuit Diagram (2) - Specific Requirements of LED Drive Power Supply**
LEDs are low-voltage light-emitting devices known for their long life, high efficiency, safety, and environmental friendliness. For mains AC input, the output must be isolated for safety. Higher efficiency in the drive power supply is better, as it enhances the energy-saving performance of LEDs. High switching frequency and efficiency also allow for compact LED lamp designs. High constant current accuracy ensures consistent brightness and color when using large numbers of LEDs.
**Power LED Lamp Cup Application Scheme Below 10W**
Power LEDs under 10W are widely used, with many integrated products available where the driver and LED are combined in one lamp, making them convenient for users. Common specifications include GU10, E27, and PAR30. For this application, we have designed a scheme based on the AP3766 chip, which offers primary-side control without the need for optocouplers or secondary current control circuits. This simplifies the design and improves efficiency. The AP3766 uses sub-micron startup current technology, reducing power loss and improving system efficiency. It also features constant current tightening for accurate output and is packaged in a small SOT-23-5 package, making it suitable for installation in standard lamp cups. It includes isolation, open-circuit protection, overvoltage protection, and short-circuit protection, while using a transistor instead of a high-voltage FET to lower costs.
**LED Lamp Drive Power Circuit Diagram (3)**
This schematic shows a driver circuit for an AR111 LED with a 5S2P configuration. The MAX16819 operates in buck-boost mode, providing an average of 500mA per LED string from a 12VAC input. The circuit uses MAX16819 as the main controller, capable of driving up to 10 LEDs in a 5S2P configuration. The input voltage is 12VAC with ±10% tolerance. Schottky diodes D1–D4 form a full-wave rectifier, and capacitors C1–C8 are used for filtering. Some capacitors can be removed to reduce cost, depending on the LED flashing requirements. The design also includes tantalum capacitors for stable temperature performance.
**LED Lamp Drive Power Circuit Diagram (4)**
This design uses the TNY279 power chip as the control element of the switching power supply. The TNY279 integrates a 700V high-voltage MOSFET switch and a power controller, operating in a simple on/off control mode rather than traditional PWM. It includes features such as automatic restart, frequency jitter, and protection mechanisms like overtemperature and overcurrent protection. The core part of the power supply uses a flyback converter, which is simple and easy to implement. The input rectification filter circuit includes passive PFC to improve the conduction angle and reduce harmonic distortion. The high-frequency transformer design uses bias windings to provide overvoltage protection and reduce no-load power consumption.
**LED Lamp Drive Power Circuit Diagram (5)**
LED drive power supplies convert the input power into specific voltage and current to drive LEDs. Inputs can include high-voltage AC, low-voltage DC, or high-voltage DC. Modern LED drivers use patented ICs that eliminate the need for electrolytic capacitors, extending lifespan and reducing size. These drivers are small and can fit inside standard LED bulbs without changing the original shape, making them user-friendly and efficient.
**Recommended: Common LED Driver Power Circuit Design (Detailed 10 Circuit Schematics)**
A variety of LED driver circuits exist, including buck/boost converters, flyback converters, and others. Each topology has its own advantages, but the buck-boost regulator is generally more efficient. The LTC3783 supports multiple topologies, making it versatile for different applications. By adjusting components like R5 and R7/R8, the circuit can be configured for various input and output conditions, ensuring flexibility and high efficiency.
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