Talking about the Design and Application of LED Driver Power Supply

LEDs have low energy consumption, long life, low heat generation, environmental protection, etc., and have been widely used in many fields, such as:

a. Lighting field street lights, ramp lights, LED grille lights, LED indoor lights, LED ceiling lights, etc.

b. Landscape lighting buildings, roads and bridges, square building facilities, lawn lights, curtain wall lights, etc.

c. used as a backlight mobile phone, computer, etc.

d. Information plane display display board, dynamic billboards, simulation animation, sports venues, industry and commerce, other industries, etc.

e. Indicators and internal reading lights in the car compartment, brake lights, taillights, turn signals, side lights, etc.

f. Explosion-proof lamps for special fields, miner lamps for mining production, etc.

An LED is an LED with diode characteristics that can only be energized in one direction. Generally, the LED brightness output is proportional to the LED current, but the white LED will appear saturated under high current, and the luminous efficiency is greatly reduced or even failed. Therefore, the LED current cannot exceed its specification. In addition, the LED brightness output is inversely proportional to the temperature, so the heat dissipation and well-designed heat dissipation system should be minimized during use.

At present, LEDs are all driven by DC, so a power adapter, that is, an LED driver, needs to be added between the mains and the LEDs. Its function is to convert AC mains into DC power for suitable LEDs. According to the power consumption rules of the power grid and the driving characteristics of the LED, the following points should be considered when selecting and designing the LED driver power supply:

a. High reliability

Especially like the driving power supply of LED street lamps, it is installed at high altitude, the maintenance is inconvenient, and the maintenance cost is also large.

b. High-efficiency LEDs are energy-saving products, and the efficiency of driving power supplies is high. It is especially important for structures where the power supply is installed in the luminaire. Since the luminous efficiency of the LED decreases as the temperature of the LED increases, the heat dissipation of the LED is very important. The power supply has high efficiency, its power consumption is small, and the heat generated in the lamp is small, which reduces the temperature rise of the lamp. It is beneficial to delay the light decay of LEDs.

c. High power factor The power factor is the grid's load requirements. Generally, there are no mandatory indicators for electrical appliances below 70 watts. Although the power factor of a single power consumer with low power has little effect on the power grid, at night, everyone lights up, and the similar load is too concentrated, which will cause serious pollution to the power grid. For 30 watts to 40 watts of LED driver power, it is said that in the near future, there may be certain indicators for power factors.

d. There are two types of driving methods: one is a constant voltage source for multiple constant current sources, and each constant current source supplies power to each LED separately. In this way, the combination is flexible, and all the LED faults do not affect the work of other LEDs, but the cost will be slightly higher. The other is direct constant current supply, with LEDs running in series or in parallel. Its advantage is that the cost is lower, but the flexibility is poor, and it is necessary to solve a certain LED failure without affecting the operation of other LEDs. These two forms coexist for a while. Multi-channel constant current output power supply mode will be better in terms of cost and performance. Perhaps it is the mainstream direction in the future.

e. Surge protection LEDs are relatively poor in their ability to withstand surges, especially against reverse voltage capability. It is also important to strengthen protection in this area. Some LED lights are installed outdoors, such as LED street lights. Due to the start of the grid load and the induction of lightning strikes, various surges will be invaded from the grid system, and some surges will cause LED damage. Therefore, the LED driver power supply must have the ability to suppress the intrusion of surges and protect the LEDs from damage.

f. Protection function power supply In addition to the conventional protection function, it is better to increase the LED temperature negative feedback in the constant current output to prevent the LED temperature from being too high.

g. For the protection aspect of the lamp, the power supply structure should be waterproof and moisture-proof, and the outer casing should be light-resistant.

h. The life of the drive power must match the life of the LED.

i. Meet safety and electromagnetic compatibility requirements.

With the increasing use of LEDs, the performance of LED drive power will be more and more suitable for LED requirements. The LED power supply (EWV-XXX XXX SS and EWI-XXX XXX SS series) of Infineon Electronics (Hangzhou) Co., Ltd. is described below.

Characteristics

High efficiency (typical value 95%)

High power factor (typically 0.98)

Input surge protection

Power supply overcurrent, overvoltage, short circuit, over temperature protection

Waterproof (IP67)

Safety and EMC comply with domestic and international standards

Technical parameters and indicators

Enter EWV EWI

Voltage AC90～264V

Frequency 47~63Hz

Power factor 0.98 0.96 ((typical)

Output EWV EWI

Power W 90/120/150/200/300 10/20/30/45

Voltage V 12/24/36//48/54

Current mA 350

Efficiency 95% (typical) 90% (typical)

surroundings

Operating temperature -25 ° C ~ +60 ° C

Storage temperature -40 ° C ~ +85 ° C

Safety and electromagnetic compatibility

Safety regulations: UL/CUL, TUV, CE

EMI: EN55022:1998, +A1:2000+A2:2003, ClassB

CISPR22:2003,, ClassB

AS/NZS CISPR22:2004, ClassB

EMS: EN61000-3-2 EN61000-3-3

EN61000-4-2 EN61000-4-4

EN61000-4-5 EN61000-4-6

EN61000-4-8 EN61000-4-11