Classification analysis of the LED power

classification analysis of the LED power supply 1, press the drive can be LED Display Screen into two categories
1.1 constant-current type < p> a, constant current drive circuit output current is constant, and output DC voltage as the load resistance is within a certain range of different sizes change, the load resistance is small, the output voltage is low, the greater the load resistance , the higher the output voltage;
b, constant current circuit is not afraid of the load short-circuit, but the non-load completely open.
c, led constant current driver Mercedes dvd is an ideal drive, but the relatively higher prices.
d, the maximum tolerance should be noted that the use of current and voltage, which limits the number of LED's use;
1.2 regulator type
a, when the steady pressure to determine the parameters of the circuit after the output voltage is fixed, while the output load current is the increase or decrease with changes;
b, open circuit voltage regulator circuit is not afraid of the load, but the non-load full short circuit.
c, the regulator drive circuit drive the LED, each with an appropriate resistor string requires only that the average brightness of each string of LED display;
d, brightness will be affected by rectification from the voltage change.
2, the circuit structure by way of classification
2.1 resistor, capacitor step-down mode
through capacitor step-down, use the flash, due to charge and discharge the role of instantaneous current through the LED a great, easy to damage the chip. Vulnerable to voltage fluctuations, power efficiency is low, and low reliability.
2.2 resistance buck mode
buck through resistance, interference by the larger power grid voltage, regulated power supply is not easy to make, step-down resistor to consume a large proportion of energy, so this is very low power efficiency power supply, and the system's reliability is also low.
2.3 conventional  Cooling tower step-down mode
power, small size, the weight of too much weight, power efficiency is very low, generally only 45% to 60%, so seldom used, reliability is not high.
2.4 electronic transformer step-down mode
lower power efficiency, voltage range is not wide, generally 180 ~ 240V, wave interference.
2.5 RCC buck mode switching power supply
voltage range is wide, the power efficiency is relatively high, generally can be 70% to 80% wider applications. Because of this control mode oscillation frequency is not continuous, switching frequency is not easy to control, load voltage ripple coefficient is relatively large, abnormal loads and poor adaptability.
2.6 PWM control mode switching power supply
mainly consists of four parts, part of the input rectifier, the output rectifier part, PWM voltage control part, switching energy conversion components. PWM switching regulator is the basic working principle of the input voltage, the internal parameters and led waterproof Switching Power Supply load changes, the control circuit is controlled by the difference between signal and reference signal for closed-loop feedback, adjust the main circuit switching device turn-on pulse width, makes the switching power supply output voltage or current stable (ie, the corresponding constant-current power supply or power supply). Power efficiency is extremely high, generally can be 80% to 90%, output voltage and current stability. This circuit has a good general protection handbag online, a high-reliability power supplies.