Not just a normal DC power supply! ! ! !
Led TV is the same as LCD TV. The only difference is that the LCD TV uses ccfl as the backlight and the inverter as the drive board, but the led TV uses Led as the backlight and the boost drive board works as the drive using DC, unlike the normal led, the high power led used in the TV works at 3vdc per led. The purpose of the
led driver board is to keep the current in the led constant, if the current increase in the led exceeds the predetermined level, the led recommended for production will only be the adjustable led of the fault current, if we operate the led by forcing the voltage to be higher than the required forward voltage or other factors, many people ask why the led cannot work on a normal DC power supply, for example, if a led needs 3vdc, why can\'t it work on a 3vdc power supply, why is the led in the TV tested these 3 circuits by a complex drive board to see why only the last one will work, why didn\'t the first two circuits work so well in driving the led that each diode has 3vdc to it seems like everything, right! !
However, driving the led is not simple. The problem is that if the temperature increases, the led will be sensitive to the temperature. Each led will now require a lower forward voltage and 3vdc is too high now. .
Remember, as I mentioned earlier, to force a higher forward voltage on the led, a very high current will pass in and it will eventually fail in this circuit anyway, the voltage of the whole system is very high diode string each diode can only work at its expected forward voltage, because when the temperature rises, the excess voltage will fall on the resistance, but the current can\'t keep the constant voltage down, the whole process will have a high excess voltage resistance now the current in the string is obviously the same as the cureent in the resistance, now the cureent in the resistance will be very high because in this circuit, the voltage at both ends of it is very high. if the temperature rises, each led will consume 3 volts 2. 8 vdc 2.
8*5 = 14vdc the entire string will consume 14vdc and the resistor will drop by 1 Volt, the controller will feel this 1 voltage drop and readjust its output voltage, in order to maintain the fixed set by the designer through this resistance and the current of all diode strings. .
In the first circuit, the voltage adjustment of the whole diode is not good, so the current adjustment is not good. In the second circuit, the voltage adjustment of the whole diode is very good, but the current adjustment is not only in the Third Circuit, but the voltage and current at both ends of the diode are very good. .
Keep in mind that the ultimate goal of the led drive board is to keep the current in the led constant. .
One thing I forgot to mention is why this committee is called boost! !
The reason it is called This is because its output voltage is much higher than the input voltage, and it is easy to accept 30 to 50 Vdc and within the range of 100 to 17vdc, can drive a very large string of LEDs. Please contact me if you would like to purchase an ebook. Yahoo.
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