LED driver's parameters
Input voltage range
Users see the indicated input voltage range of the power supply is 85-265VAC. It is 100-240VAC when actual use. In fact, the so-called weighing ± 10% test is performed (IEC60950 is tightened + 6% - 10%), so the voltage range defined by the power supply specification does not have problems; and the power supply is satisfied with the safety specification and ensures that the user can correctly input the power.
Power factor (PFC)
PFC (PowerFactorCorRection) power factor correction, mainly for improving the efficient power of power supply inputs and the ratio of power. Generally free of PFC lines, the power factor of its input is only 0.4 to 0.6, while the active PFC line can reach 0.95, and the relevant formula is as follows:
View power = input voltage × input current (VA)
Effective power = input voltage × input current × power factor (W)
From environmentally friendly perspectives: Power company power plants must produce electric energy than the power, and their generator sets can stabilize market energy demand, and the actual use of electrical energy is effective power. If the power factor is 0.5, it indicates that the generator set is greater than 2VA power, which can safely supply the power 1W, and its energy operation is poor. Conversely, if the power factor is improved to 0.95, the power company generator set is not problematic as long as it is more than 1.06VA power, and the energy supply of 1W is not problematic, and the energy efficiency is better.
Protective function
Overvoltage / overcurrent / overload / overload / overload / overloading refers to the power supply to threaten the safety of power from internal and external conditions such as input power, load, environment, cooling circuit, or device failure, resulting in power supply to work properly, The relevant circuit function is activated and the protection action occurs.
OVP: OvervoltageProtection. One characteristic of the switching power supply circuit protects the switching power supply and load when the output is abnormal.
Undervoltage protection: When the power supply voltage of the protected line is below a certain value, the protector cuts the line; when the power supply voltage is restored to the normal range, the protector is automatically turned on.
OCP: OvercurrentProtection. In the DC switch supply circuit, in order to protect the adjustment tube, it is not burned when the current is short-circuited. The basic method is that when the output current exceeds a value, the adjustment tube is in the reverse bias state, thereby turning off, automatically cutting circuit current.
Short-circuit protection ShortCircuitProtection: The output current of the switching power supply is limited to a security value to protect the switching power supply is not damaged.
OTP: OvertemperatureProtection. High intensive and lightweight small volume in the DC switching power supply, so that the power density in its unit volume is greatly improved, so if the components inside the power supply device work ambient temperature There is no corresponding improvement, which will inevitably deteriorate the circuit performance, and the components have failed. Therefore, the heat protection circuit should be set in the high-power DC switching power supply.
Protection (action) has the following ways:
1. Restart (turn on again after disconnecting the power, the power is restored to normal. Automatic and manual);
2. Strike (HICCUP: intermittent output);
3. FoldBackLimiting (when the load is close to short circuit, the output current to normal value);
4. CoctantCurrentlim or constant current, limiting output current is not infinitely increased due to overload or short circuit of the load. Even if the load is short-circuited, it does not cause device shutdown and power corruption).
5. Downtime / overload / overload / over - temperature fault, usually refers to the dangerous state when the output current / power / (or input) voltage and the radiator temperature exceeds the power supply of the protected threshold.
Inrush current
Exchange power supply will appear short (1/2 ~ 1 power cycle, EX: 60Hz power supply 1/120 ~ 1/60 second) large current (according to product design is about 20 ~ 60A) Please refer to the product specification). After the product is turned on, it will return to normal current input. Each time it will appear in the moment of power input, this is normal, and does not cause damage to the power supply. However, it is not recommended to turn on / off for power supply. It should be noted that if you use a plurality of power supplies to boot in the same time, it is possible to cause the protection switch of the system power distribution. It is recommended that multiple power supply room delay boot, or the remote control function of the power supply. The order of sequential delay is turned on.
Output voltage accuracy
The output voltage accuracy refers to the difference between the actual output voltage and the rated output voltage, which is a superposition value of the line stability and load stability. Usually this parameter is at +/- 1% line stability refers to the percentage of the output voltage from the rated voltage when the input voltage varies between the maximum and minimum values of the allowable range. The load stability refers to the output voltage deviates from the ratio of the rated voltage when the output load current varies between the maximum and minimum values of the allowable range.
Second, why drive the LED lamp with a constant current power supply?
The life of the LED refers to the time of light attenuation, and the constant current drive is controlled by the current of the LED, ensuring that the junction temperature of the LED chip will not be too high to prevent the semiconductor chip, package material, and fluorescent material from abnormal aging. The LED of the LED will not be lowered (ie, light failure). With other types of power, due to the constant current of the LED, it is not easy to control because of its temperature rise, resulting in light decay.
The LED is proportional to the current size. Therefore, the LED drive power supply requires constant current output characteristics to ensure that the LED can obtain stable luminescence intensity and manufacturer's long life during use. The constant current power supply To ensure the constant current drive LED, the LED must be connected in series to ensure that the current of each LED in the circuit is equal and constant. When the power demand of the LED lamp group is getting larger, the number of LEDs is increasing, and the voltage demand is more than the series, and the result voltage is getting higher and higher. It is easy to have problems, manufacturing and use requirements will be more stringent. This will bring costs to the power supply and difficulties in use. Therefore, the driver of high-power LEDs has a low voltage driver.
The power supply of the CV + CC can be operated in constant pressure or on constant current.
IP level
Efficiency EffICIENCY: The ratio of the total output power in the percentage represents the power input power. That is: efficiency = output power / input power * 100%.
Rated power: refers to the maximum output power of the power supply (the product of voltage V and current A).
EMC: Electromagnetic compatibility (EMC) means that the device or system meets the ability to run in its electromagnetic environment and do not have an unbearable electromagnetic interference in any device in its environment. EMC includes EMI (electromagnetic interference) and EMS (electromagnetic tolerance) two departments, so-called EMI electromagnetic interference, is harmful energy for switching power supply or radiation. The EMS refers to the power supply that is not affected by the surrounding electromagnetic environment during the implementation of the performance.
Ripple: Since the DC stabilization power is generally formed by the alternating current power supply, it is not avoided in the DC stabilization amount with some of the AC components, this superimposed alternating power component on DC stabilization It is called ripple.
Output ripple and noise RIPPLEANDNOISE, OUTPUT: In the specified bandwidth, the switching power supply outputs the amplitude of the AC voltage, usually used with a moth of peak value or RMS value.
Total harmonic distortion: TotalharmonicDistion, referred to as THD. When refers to the signal source input, the output signal (harmonic and its multiplier component) is typically represented by a percentage than the additional harmonic portion of the input signal. Generally, the total harmonic distortion at 1000 Hz frequency is the smallest, so many products are distorted by this frequency as its indicator. Therefore, when testing the total harmonic distortion, it is a sound of 1000 Hz to detect, the smaller this value, the better.
Overshoot and Undershoot: The overshoot is the first peak or valley value exceeds the set voltage - the maximum voltage is the highest voltage for the rising edge and the lowest voltage is referred to. The downhole refers to the next valley or peak. Excessive overshoot can cause protection diode work, resulting in prematurely failure. Excessive downstones can cause false clocks or data errors.
Working ambient temperature Temperature, Operatingambient: The switching power supply can reasonably electrical index and stability temperature range. Unless otherwise stated, do not think that the switching power supply can output full power throughout the temperature range, nor does it say that the switching power supply maintains the same electrical indicators throughout the operating temperature range.
PWM: Pulse Width Modulation: A voltage adjustment method used by a switching power supply refers to the width control output by changing the pulse sequence.
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