LEDs are widely used in E27, GU10, PAR lamps, MR16 and other fields. However, in the LED-MR16 application driven by electronic transformers, there are some problems.
There are four main reasons for these problems:
First, the normal power of the MR16 lamp cup for LED is only 5W. The magnetizing current generated in the half-bridge circuit cannot saturate the internal transformer, and the electronic transformer works in an abnormal state.
Second, MR16 has a large electrolytic capacitor after the rectifier bridge, which is equivalent to the load of the electronic transformer from the original pure group load to a large capacitive load.
Third, in a 5W application, a capacitor larger than 487 (uF) is required to make the Buck circuit work properly. It is impossible to place such a large-capacity capacitor in a very demanding MR16 lamp cup.
Fourth, the output voltage of the electronic transformer is not a sine wave. It is a triangular-like wave with a minimum of 5.6V. If the operating voltage cannot reach 5.6V or lower, a larger filter capacitor is needed, otherwise the LED output current will be lower at VCE. When the chip's operating voltage drops to zero, there may be a low frequency flicker of 100 Hz or a regular flicker of the time interval determined by the peripheral components of the IC's COMP pin.
In view of the status quo of the above industries and the reasons for the flashing, we recommend the RICHTEK8479 solution, which is a Two-StageTopology (Boost+Buck) architecture, and has a wide operating voltage of 4.5Vto36V, which can easily solve the flash phenomenon and achieve stability. Output current and illumination.
The power scheme adopts a 2-stage architecture, that is, after the voltage input from the electronic transformer is subjected to fast recovery rectification, the voltage is first boosted, the voltage is raised to a constant voltage of about 20 V, and then passed through the second-stage circuit, and The buck conversion is performed in a step-down constant current mode to keep the output current constant over a certain output voltage range.
Since the IC has two MOS tubes built in, the peripheral circuit becomes compact and simple, and since the scheme adopts a boosting structure, the input terminal does not need to use a large-capacity electrolytic capacitor to stabilize the input voltage, which is very suitable for application in the MR16 base, etc. Space is small.
This Power Supply can achieve a good constant current effect from a wide input voltage range of 8V to 19V, regardless of AC or DC input status. LED-MR16 spotlights will replace the halogen spotlights. The electronic transformer-driven power supply solution for the M7-MR16 spotlight explores a way to achieve a very compatible drive power supply.
5V Power Supply, it has multi plug were suitable for many countries. We can meet your specific requirement of the products, like label design. The plug type is US/UK/AU/EU. The material of this product is PC+ABS. All condition of our product is 100% brand new.
Our products built with input/output overvoltage protection, input/output overcurrent protection, over temperature protection, over power protection and short circuit protection. You can send more details of this product, so that we can offer best service to you!
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