IS31LT3948 AC DEMO BOARD GUIDE DESCRIPTION RECOMMENDED EQUIPMENT IS31LT3948 is a PFM step-up DC-DC converter 30VDC Power supply designed for driving the white LED arrays for large size LED panel (1W LED, 12 LEDs in series) LCD panel backlighting applications. With internal OVP Multi-meter circuit, the chip and the system can be safe even if the load is not connected. The device features external PWM dimming or DC dimming, which allows the RECOMMENDED INPUT AND OUTPUT RATINGS flexible control of the backlighting luminance. Input: 12VAC IS31LT3948 incorporates a unique FB scheme which Output: 12LEDs in series/333mA automatically adjusts the integrated DC/DC converter to the optimum output voltage for the system, Note: The input voltage must be lower than the output voltage maximizing the efficiency. (total V ). F IS31LT3948 general DEMO board is used in general lamp. ABSOLUTE MAXIMUM RATINGS Input voltage 15VDC FEATURES voltage 45VDC Wide input voltage range: 5V~100V Caution: Do not exceed the conditions listed above, otherwise Constant Current Output limited only by external the board will be damaged or output current will be limited. component selection (Note) No loop compensation required PROCEDURE Internal over-voltage protection The IS31LT3948 DEMO Board is fully assembled and Internal over-temperature protection tested. Follow the steps listed below to verify board Note: The maximum output current is determined by Vout/Vin operation. ratio as well as the external components. If output current and Vout/Vin ratio is high, high current components of inductor and Caution: Do not turn on the power supply until all connections NMOS are needed. are completed. 1) Connect the terminals of the power supply to the QUICK START VIN1 and VIN2 pin (If the board dont have the rectifier(D1,D3~D5), connect the positive terminal of the power supply to the VIN1 of the board and the negative terminal of power supply to the VIN2 of the board) . 2) Connect the negative of the LED panel (LED arrays) to the LED- terminal. 3) Connect the positive of the LED panel (LED arrays) to the LED+ terminal. 4) Turn on the power supply and the LED panel (LED arrays) will be light. Figure 1: Photo of IS31LT3948 Evaluation Board ORDERING INFORMATION Part No. Temperature Range Package IS31LT3948-GRLS2-EBAC -40C ~ +85C (Industrial) SOP-8-EP, Lead-free Table 1: Ordering Information For pricing, delivery, and ordering information, please contacts Lumissils analog marketing team at analog Lumissil.com or (408) 969-6600. Lumissil Microsystems www.lumissil.com 1 Rev.A, 08/26/2013 IS31LT3948 AC DEMO BOARD GUIDE Figure 2: IS31LT3948 DEMO Board Schematic BILL OF MATERIALS Name Symbol Description Qty Supplier Part No. LED Driver U1 HBLED Driver 1 Lumissil IS31LT3948 AL Capacitor C1,C2 CAP,220F,35V,10% 2 AL Capacitor C5 NC 1 AL Capacitor C3 220F10%,63V,Low ESR 1 SMD Capacitor C4 10F20%,25V 1 SMD Resistor R1 2.4k5%,1206 1 SMD Resistor R2 NC 1 SMD Resistor R3 430k 1%,0805 1 SMD Resistor R4 24k1%,0805 1 SMD Resistor R5,R6 0.221%,1206 2 SMD Resistor R7 10k1%,0805 1 SMD Resistor R8,R9 1.81%,1206 2 SMD Resistor R10 0,0805 1 SMD Resistor R11 NC 1 Schottky Diode D1~D6 SS36,3A,60V,SMA 6 Diode DS 1N4007,1A,1000V,SMA 1 SMD Inductor L1 100H,Isat3A 1 MOS Q1 11A,100V,13N10L,NMOS,TO-252 1 MOS Q2 NC 1 Lumissil Microsystems www.lumissil.com 2 Rev.A, 08/26/2013