Based on the characteristics of the power grid, the requirements of LED characteristics, and related LED products, the following points should be considered when selecting an LED driver power supply:
General Principles
a. Ideally, a constant current driver should be used based on the current and voltage characteristics of LEDs. This avoids current fluctuations caused by changes in the LED's forward voltage, while a constant current ensures stable LED brightness.
b. Furthermore, LED luminous flux is inversely proportional to temperature, so it's crucial to minimize power supply heat generation and design a well-designed heat dissipation system to lower the ambient temperature of the LED.
c. To ensure the overall lifespan of LED products, the junction temperature of the LED must be controlled within a certain range, i.e., the operating ambient temperature of the LED product must be well controlled.
High Reliability
LED products mainly consist of LED chips, power supplies, heat sinks, and control circuits. The quality of the LED power supply directly affects the quality of the product. This is especially important for LED streetlights, which are installed at high altitudes, making maintenance inconvenient and costly.
High Efficiency
LEDs are energy-saving products, and the driver power supply must also meet energy-saving requirements. The structure of the power supply installed inside the lamp is particularly important, as the luminous efficiency of LEDs decreases as the LED temperature increases.
High Efficiency Power Supply
High efficiency results in low power loss and less heat generation within the lamp, thus reducing the lamp's temperature rise and contributing to slower LED light decay.
Constant Current Drive
To match the volt-ampere characteristics of LEDs, LED power supplies must use a constant current drive.
Surge Protection
LEDs have relatively poor shock resistance, so enhanced protection is crucial. This is especially important for outdoor installations, where power grid load starts and stops, and lightning strikes can impact the power supply. Therefore, the LED driver power supply input should have surge protection circuitry to prevent damage to the LEDs during switching.
Temperature Protection
In addition to standard protection functions, it's best to add LED chip temperature negative feedback to the constant current output to prevent overheating of the LED chip's PN junction.
Operating Environment
Due to varying environmental conditions, the working environment of the LED lamps must be carefully considered, including temperature, humidity, and installation location.
Given the power supply's operating method, without a soft-start circuit, a voltage spike will occur at power-on. Therefore, a soft-start circuit is necessary for better LED protection. This is a key factor in the stability of the drive power supply .
