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ULW2091L-T92-K Datasheet(PDF) 10 Page - Unisonic Technologies |
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ULW2091L-T92-K Datasheet(HTML) 10 Page - Unisonic Technologies |
10 / 12 page ULW2091 Preliminary LINEAR INTEGRATED CIRCUIT UNISONICTECHNOLOGIESCO.,LTD 10 of 12 www.unisonic.com.tw QW-R125-044.c APPLICATION INFORMATION ULW2091 is a constant current driver IC for LED lighting, which is applied to the non isolated LED driver power supply. The 500V power switch is integrated in the chip, which is based on the constant current architecture and control method, and it can achieve excellent constant current characteristics with minimal external components. And without auxiliary winding power supply and testing, the system cost is very low. Start After the system is powered up, the input voltage is charged on the VDD pin through the jfet, and when the VDD voltage reaches the threshold value, the chip's internal reference circuit begins to work. When the chip is working normally, the required operating current is still through the supply of internal consumption. Constant current control The chip is detected the peak current, and the RCS resistance is connected to the input terminal of the peak comparator, which is compared with the threshold voltage 0.6V. When the RCS voltage reaches the threshold, the LED current is adjusted, and realized the constant current control. The formula for calculating the inductor peak current is IPK=600/RCS (mA). Among them, RCS is a current sampling resistor. The output of the comparator CS also includes a 500ns leading edge blanking time. The formula for calculating the LED average current is ILED=IPK/2. Among them, IPK is the inductor peak current. Protection function ULW2091 built in a variety of protection functions, including LED short-circuit protection, LED open circuit protection, sampling circuit short-circuit protection, temperature regulation and protection, etc. When LED short circuit, the system works in the 3 KHz low frequency, so the power consumption is very low. Over temperature adjustment function ULW2091 has the function of over temperature adjustment, the output current is gradually reduced when the driving power is over, so that the output power and temperature rise is controlled, the power supply is maintained at the set value, In order to improve the reliability of the system, the chip is internally set to adjust the temperature of the 140°C. PCB design In the design of PCB, you need to follow the following guidelines: VDD bypass capacitor is required to close the VDD pin of the chip. RCS resistor requires close to the CS pin of the chip Between RCS and VDD bypass capacitor resistor connected to the copper foil as short as possible CS pin increases in the area of copper clad to improve chip cooling. |
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