source:other news release time:2023-08-02 Hits: Popular:led screen wholesaler
Due to the limitation of LED power level, it is usually necessary to drive multiple LEDs simultaneously to meet the brightness requirements. Therefore, a dedicated driving circuit is required to illuminate the LEDs.
Resistance capacitance voltage reduction: Utilizing the impedance of the capacitor under AC to limit the input current and obtain a DC level to power the LED. Simple structure, low cost, non isolated input scheme, and potential safety hazards. The conversion efficiency is very low and cannot achieve constant current control.
2. Isolation flyback circuit: By using a flyback circuit, a DC level is generated on the secondary side through a variable voltage vapor pressure crow stool device,
Then, the ripple of this level is fed back to the original edge through the optocoupler, thereby achieving self-excited stability. Tearful Master
This type of circuit meets the requirements of safety regulations, and has good output constant current accuracy and high conversion efficiency. However, due to the need for optocouplers and secondary constant current control circuits, the system is complex, bulky, and costly.
3. Primary side solution: By completely controlling the output of the electric plow source and current on the AC primary side, the most accurate can achieve a constant current accuracy of 5%, and the secondary side only needs a simple output circuit.
The primary side mainly relies on feedback from the auxiliary side to control the output voltage, relies on current limiting resistors to control the primary side current, and multiplies the turn ratio to control the accuracy of the output current.
The original edge scheme inherits the various advantages of isolated flyback circuits, while having a simple architecture that can achieve small size and low cost.
The constant current accuracy problem of the primary side: Due to the difficulty in controlling the production accuracy of the transformer, the output current drift of the primary side scheme is large when using low-quality transformers. So, the original edge scheme has added a secondary constant current control circuit through improvement. Although it is more complex than the ordinary original edge scheme, compared to the flyback scheme, it can still eliminate optocouplers and achieve the highest cost-effectiveness of the system.
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