Sinrace Power Supply Technology (Shenzhen) Co., Ltd.

First, LED drive power supply can by divided into two categories according to drive mode:

A. constant flow:

1, To drive LED by constant current driver circuit is ideal ,but the disadvantage is of higher price.

2, although the constant current circuit not afraid to load short-circuit, but the non-load fully open.

3, the constant current drive circuit output current is constant, while the output DC voltage is different with the size of the load resistance in a certain range.

 4, to limit the number of LED, because it has to withstand the maximum current and voltage values.

 B. Voltage regulator:

 1, the regulator circuit to determine the parameters, the output is a fixed voltage, output current but increase or decrease as the load changes.

 2, although not afraid to load open circuit voltage regulator, but completely short-circuit the load is strictly prohibited.

 3, the rectified voltage change will affect LED brightness.

 4, to make the voltage regulator circuit to drive each string of LED display brightness uniformity, need to add appropriate resistance can.

 Second, LED power supply can be divided into six categories according to circuit structure:

 1, the conventional step-down transformer:

 This power has the advantage of small size, the downside is the weight of too much weight, power efficiency is very low, generally 45% to 60%, because the reliability is not high, so seldom used.

 2, the electronic transformer step-down:

 The downside is that the power structure of the low conversion efficiency, narrow voltage range, usually 180 ~ 240V, large ripple interference.

 3, capacitor step-down:

 In this way the LED power supply vulnerable to the impact of voltage fluctuations, power supply, low efficiency, should not be flashing LED in use, because the circuit through the capacitor step-down, when used in the flashing, the role of the charge and discharge, the instantaneous current through the LED great, easy to damage the chip.

 4, the resistance step-down:

 This power supply is very low power efficiency, and reliability of the systems is also low. Because the step-down circuit through the resistor, the voltage change by the interference of the larger power grid is not easy to make power supply and consumption dropping resistor itself, but also much of the energy.

 5, RCC buck switching power supply:

 LED power advantages of this approach is relatively wide voltage range, power efficiency is relatively high, generally 70% to 80%, a wider application. Disadvantages are difficult to control the switching frequency, the larger the load voltage ripple factor, abnormal load poor adaptability.

 6, PWM control of switching power supply:

 At present, PWM control design LED power supply is ideal, because the switching power supply's output voltage or current is very stable. High power conversion efficiency can generally be as high as 80% to 90%, and the output voltage, current is very stable. In this way the LED power supply which mainly consists of four parts are: input rectifier filter section, part of the output rectifier filter, PWM voltage control section, the switching energy conversion parts. and this protection circuit are well , is a high reliability of power supply.