[Source: "High - tech LED - Technology and Applications" November issue]
Taiwan Feihong Integrated Circuit Co., Ltd. is the first driver of the high-voltage LED lighting driver EC4211 with high brightness, high energy saving, low heat and transformer-free. It is a constant current linear LED driver that drives power factors up to 0.95 and can be used up to 265V. It is determined by an external resistor to determine the constant current. The accuracy of the drive current is up to ±5%. The internal foldback thermal protection function adjusts the current through the LED by the current limit when the system temperature is too high. Minimize heat. The chip is available in SOP-8L, DFN-8L, and TO252-5L packages for flexible LED lighting design. Figure 1 shows the basic principle of application with EC4211, and Table 1 shows the material for the 4W LED drive design.
Table 1 shows that the AC-driven LED circuit designed with EC4211 is very simple and requires only six components. For a 220V LED lamp, the maximum current is 240V. Its current and voltage waveform is shown in Figure 2.
Figure 2 shows that when the 220V standard power supply is working, the LED has a current from the phase angle of 40 degrees of the power supply in the half cycle of the power supply, and the current reaches 30mA when it reaches 50.5 degrees, and then decreases to 130 degrees. It is zero at 140 degrees and its input power is 4.2W. There are 44% time for 30mA and 12.2% time average current is 15mA. According to the LED illuminating characteristics, the luminous efficiency is 100% at a rated current of 20 mA, and the luminous flux per mA current is 70 X 3.2=224 lm with a 100 lm light source. The luminous efficiency is 1.08 times at 15 mA and 0.85 times at 30 mA. .
The amount of luminescence is (15 X 0.122 X 1.08 + 30 X 0.85 X 0.44) X22.4=296lm
The overall efficiency is 296/4.2=70%
The duty ratio and the amount of luminescence when the LEDs are operated for different power supply voltage inputs are different, and various performance indexes are described in Table 2.
It can be seen from Table 2 that the input power of the EC4211 increases nonlinearly with the voltage. When the voltage is reduced to 190V, the input power is less than 70%, the brightness is reduced to less than 80%; when the voltage is raised to 250V, the power rises to 1.25 times the rated power and the overall efficiency is reduced to 64%, and the EC4211 consumes The power is 0.15W at 190V and rises to 1.124W at 250V. When the voltage is higher than the rated voltage by more than 10%, since the power consumption of the EC4211 is more than 0.8W, the chip temperature rises faster. When the temperature exceeds 100 degrees, the internal fold-back thermal protection function of the chip adjusts the over-temperature protection to start. The current through the LED is shown in Figure 3.
Unfinished
      For more information, please refer to "High - tech LED - Technology and Applications" November issue
Taiwan Feihong Integrated Circuit Co., Ltd. is the first driver of the high-voltage LED lighting driver EC4211 with high brightness, high energy saving, low heat and transformer-free. It is a constant current linear LED driver that drives power factors up to 0.95 and can be used up to 265V. It is determined by an external resistor to determine the constant current. The accuracy of the drive current is up to ±5%. The internal foldback thermal protection function adjusts the current through the LED by the current limit when the system temperature is too high. Minimize heat. The chip is available in SOP-8L, DFN-8L, and TO252-5L packages for flexible LED lighting design. Figure 1 shows the basic principle of application with EC4211, and Table 1 shows the material for the 4W LED drive design.
Table 1 shows that the AC-driven LED circuit designed with EC4211 is very simple and requires only six components. For a 220V LED lamp, the maximum current is 240V. Its current and voltage waveform is shown in Figure 2.
Figure 2 shows that when the 220V standard power supply is working, the LED has a current from the phase angle of 40 degrees of the power supply in the half cycle of the power supply, and the current reaches 30mA when it reaches 50.5 degrees, and then decreases to 130 degrees. It is zero at 140 degrees and its input power is 4.2W. There are 44% time for 30mA and 12.2% time average current is 15mA. According to the LED illuminating characteristics, the luminous efficiency is 100% at a rated current of 20 mA, and the luminous flux per mA current is 70 X 3.2=224 lm with a 100 lm light source. The luminous efficiency is 1.08 times at 15 mA and 0.85 times at 30 mA. .
The amount of luminescence is (15 X 0.122 X 1.08 + 30 X 0.85 X 0.44) X22.4=296lm
The overall efficiency is 296/4.2=70%
The duty ratio and the amount of luminescence when the LEDs are operated for different power supply voltage inputs are different, and various performance indexes are described in Table 2.
It can be seen from Table 2 that the input power of the EC4211 increases nonlinearly with the voltage. When the voltage is reduced to 190V, the input power is less than 70%, the brightness is reduced to less than 80%; when the voltage is raised to 250V, the power rises to 1.25 times the rated power and the overall efficiency is reduced to 64%, and the EC4211 consumes The power is 0.15W at 190V and rises to 1.124W at 250V. When the voltage is higher than the rated voltage by more than 10%, since the power consumption of the EC4211 is more than 0.8W, the chip temperature rises faster. When the temperature exceeds 100 degrees, the internal fold-back thermal protection function of the chip adjusts the over-temperature protection to start. The current through the LED is shown in Figure 3.
Unfinished
      For more information, please refer to "High - tech LED - Technology and Applications" November issue
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