Driving method for led driver

Abstract

The invention discloses an AC input detection and starting circuit of an LED driver and an LED driving method. The AC input detection and starting circuit of the LED driver includes a filter and an intermediate voltage feedback network; wherein the filter includes a fifth resistor , the sixth resistor and the third capacitor, one end of the fifth resistor is connected to the output end of the rectifier bridge, the other end is connected to the sixth resistor and one end of the third capacitor, the other end of the sixth resistor is connected to the other end of the third capacitor to ground ; The rectifier bridge filter output detection terminal is connected between the fifth resistor and the sixth resistor; the intermediate stage voltage feedback network includes the third resistor and the fourth resistor, one end of the third resistor is connected to the cathode of the fifth diode, and the fourth One end of the resistor is grounded, and the bus voltage detection end is connected between the third resistor and the fourth resistor. The implementation of the invention can make the start-up of the transformer safer, without flickering and voltage overshoot, and avoids system abnormalities related to overvoltage during the start-up process.

Description

technical field [0001] The invention belongs to the field of LEDs, in particular to an AC input detection and starting circuit of an LED driver and an LED driving method. Background technique [0002] In recent years, low-voltage LED lamps have begun to replace halogen lamps. Due to their advantages in light efficiency and service life, they have received widespread attention. However, there is a problem that has not been well solved in the application: electronic transformers. The electronic transformer is essentially a self-oscillating resonant transformer, which can convert power frequency alternating current into 12V voltage available for low-voltage halogen lamps. Because it was originally designed to power purely resistive loads such as halogen lamps, and requires a large current to trigger conduction, in addition, electronic transformers are prone to accidental shutdown when they have capacitive or non-linear loads. [0003] After research by the applicant, it was fo...

AI Technical Summary

Problems solved by technology

[0002] In recent years, low-voltage LED lamps have begun to replace halogen lamps. Due to their advantages in light efficiency and service life, they have received widespread attention. However, there is a problem that has not been well solved in the application: electronic transformers.

Because it is originally designed to power purely resistive loads such as halogen lamps, and requires a large current to trigger conduction, in addition, electronic transformers are prone to accidental shutdown when they have capacitive or non-linear loads

[0003] After research by the applicant, it was found that the prior art scheme adopts a fixed-mode soft-start pulse sequence for starting the low-voltage LED. The main switching tube may switch with a large duty cycle. At this time, if the external AC power is switched on suddenly, a large inrush current and DC bus overvoltage will be generated, which will bring excessive stress to the components in the system and damage the system.

In the power-on process of the traditional low-voltage LED drive system, due to the lack of detection of AC input, a large voltage overvoltage is observed, which will cause system damage in severe cases

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