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FAQs

‧ Basic Concept

‧ Why we need led for lighting

‧Cost & Energy Saving Comparison

‧Types of circuit designs for LED constant current

‧What are the benefits that Constant Current by Switching Power Converter can bring us?

 
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Basic Concept

LED will become an important light source without doubts. Because higher electric-optical efficiency has been achieved then previous estimation, and accelerating. A year 2003 prediction said 100 Lm/W product would be delivered at year 2008, now it will be in the market next year.

Why the efficiency is so important? Because the average efficiency is around 20 Lm/W for Halogen lamp, and it’s 80 Lm/W for FLUORESCENT LIGHTS. Next year we can see the efficiency of LED will pass over the efficiency of those common general light sources. That suppose to mean people can utilize energy more efficiently from a better light source.


Why we need led for lighting

Energy efficiency
LEDs offer increased efficiency over incandescent bulbs. When comparing white light, LEDs offer more than two times better efficiency. For red, green, and blue lights, LEDs are more than 10 times more efficient.

Long life
Lifetime is estimated at 50,000 hours. If lit for four hours per day, this will provide over 35 years of operational life. If lit continuously, it will operate for more than five years.

Rugged
LEDs are rugged, solid state devices. They are not susceptible to vibration, as incandescent filaments are. ALTtek LED lights are integrated into rugged packages, made predominantly of aluminum. The lights can withstand far more abuse than glass-based bulbs, while remaining functional.

Color
LED lights are offered in Red, Green, Blue and Amber base colors.  These colors are far more efficient than incandescent bulbs, which use filters to block out most of the spectrum of white light. LEDs create light in the specific color desired. LEDs can also be blended together to form virtually any color.

Low temperature operation
LEDs are based on semiconductor technology. Like other semiconductors, their temperature must be regulated to enable long life. ALTtek lamp design ensures the light will not overheat. Because of the cooling technology built into ALTtek lights, they operate far cooler than incandescent or halogen bulbs. While they are warm to the touch, the temperature is too low to burn an individual’s hand. This greatly increases the safety of the light over incandescents and halogens, both as a fire hazard and for burning an individual when touching it.


Cost & Energy Saving Comparison

EX: 1000ft2 store install 40 pieces MR16,10hours light turn-on per day.

Light-source No.of light sources Input-Voltage Total Power

Life

(Houses)

Time of Maintenance for 1 year

Electric Energy

(degree/M)

Energy Saving

(degree/M)

Money Saving

(NT$/M)

Halogen

(50W)

40 AC12V

2000W

(~0.6tons)

2,000 2 600 - -

ALT MR16-

LED(4.5W)

40 AC12V

180W

(~0.045tons)

40,000 0 54 546 1256


 

 

 

 

 

NOTE1. 1KW ≒ 0.28tons(Air condition). Air condition equip. specs: 2.8KW,Energy Exhaust=1KW
NOTE2. Air condition equipment free ≒ US﹩760/tons(Taiwan price)
NOTE3. Additional air condition energy power cost and maintenance cost was not added.
NOTE4. Degree=1000Watt X 1hour=1KWh


Types of circuit designs for LED constant current

A. Current Limit by Resistor
This design can provide constant current only when DC input and LED Vf both fixed. This design has very high risk because LED Vf is not a fixed value in common. This design can not assure the current constant and will cause LED damage or other quality problems. Therefore, this design is only implemented for simple flash lights and toys, not for general lighting purpose.

B. Constant Current by Driver IC
This design uses a Driver IC to provide constant current for single LED train. This design can solve LED Vf is not a fixed value problem. Its working principle is like an active variable resistor (VR). Therefore, this design can cause a lot of Power Loss when 1) Input DC voltage is much higher than LED Vf, and 2) to drive High-Power LED with large current.

C. Constant Current by Switching Power Converter (Buck Converter)
This design use a switching IC(PWM Converter), a Freewheel Diode, and a set of LC Filter. By switching and constant current filter working principle, this design can provide constant current for LED and there is almost no power loss. This is the reason why ALT implement Switching Power Converter design on all our popular products.

What are the benefits that Constant Current by Switching Power Converter can bring us?

A. LED input current is constant. It can effectively assure the lifetime of LED.

B. Low Power Loss.

C. Input Voltage flexibility. This design allows wide range of input voltage without sacrifice LED’s lifetime.

D. LED Vf flexibility. This design accepts different Vf of LED from different Bin without sacrifice LED product quality. The LED product yield rate is assured.

E. Due to its low power loss, heat generated by LED product is minimized. High brightness LED product can be realized in a small size fixture.

- All ALT products have implemented with Constant Current by Switching Power Converter.

 

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