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KDR730E bảng dữ liệu(PDF) 4 Page - KEC(Korea Electronics) |
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KDR730E bảng dữ liệu(HTML) 4 Page - KEC(Korea Electronics) |
4 / 7 page 2007. 2. 26 4/7 KAB3403T/DN Revision No : 0 Inductor Section A 10uH inductor is sufficient for most application. The efficiency comparision of different value inductors help you design your application circuits. Inductor Section A 1uF input capacitor and output capacitor above 1uF are sufficient for most KAB3403T/DN application. Diode Selection For Diode Selection, both forward voltage drop and diode capacitance need to be considered. Schottky diodes with higher current ratings usually have lower forward voltage and larger diode capacitance, which can cause significant switching losses. A schottky diode rated at 100mA to 200mA is sufficient for most KAB3403T/DN applications. LED Current Control The LED current is controlled by the feedback resistor (RSENSE in Figure 1). The feedback reference is 320mV. The LED current is 320mV/RSENSE . The tolerance of LED Current is depends on tolerance of RSENSE and feedback reference. Open-Circuits Protection In the case of output open circuit, when LEDs are disconnected from the circuit or the LEDs fail, the feedback voltage will be zero. The KAB3403T/DN will then switch at a high duty cycle resulting in a high output voltage. But Internal Over Voltage Protection Circuits prevent output voltage ascending over OVD pin voltage(19V ~ 23V see Fig 4). This circuits is valid when driving up to 4 LEDs in series. But, when driving more than 4 LEDs in series, Normal output voltage could be over OVD pin voltage. In this case, zener diode can be used to check connect of OVD pin to LED anode.(see Fig 5) [Recommended Zener diode : KDZ3.0V] Dimming Control There are 4 different type of dimming control circuits; 1. Using a DC Voltage to CTL pin Table 2 CTL pin Voltage vs ILED Part No. Reverse Voltage (V) Forward Current (mA) Voltage Drop (V) Package KDR730E 30 200 mA 0.6V (max) at 200 mA 1.60 1.20 KDR720E 30 200 mA 0.5V(max) at 200 mA 1.60 1.20 KDR412 20 500 mA 0.5V(max) at 500 mA 1.70 2.50 LOAD CURRENT (mA) 10 74 70 64 60 82 86 90 72 78 76 68 66 62 80 84 88 05 30 15 35 20 25 4.7 µH 10 µH V IN=3.6, 4LED Inductor=Murata L1 4.7 µH ~ 22µH SW C1 1 µF C2 1 µF D1 CTL FB OVD LED1 LED2 LED3 LED4 GND VCC VIN R1 16 Ω VCC VIN GND SW C1 C2 R1 16 Ω D1 CTL FB OVD L1 4.7 µH~22µH 1 µF 1 µF LED1 LED2 LED3 LED4 LED5 LED6 KAB3403T/DN KAB3403T/DN Figure4. 4LEDs driver with Open-circuit protection. Figure5. 6LEDs driver with Open-circuit protection. Figure3. Efficiency Comparison of different value inductors Table1. Recommended Schottky Diode Description VCTL UNIT 0V~0.5V 1V~2.5V VCTL>2.5V Rate Of the LED Current 0 25 ~ 100 100 % Example : RSENSE = 16 0 5 ~ 20 20 mA |
Số phần tương tự - KDR730E |
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Mô tả tương tự - KDR730E |
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