IS31LT3948 GENERAL 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: 12VDC 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 ABSOLUTE MAXIMUM RATINGS lamp. Input voltage 30VDC voltage 45VDC FEATURES Caution: Do not exceed the conditions listed above, otherwise the board will be damaged or output current will be limited. Wide input voltage range: 5V~100V Constant Current Output limited only by external component selection (Note) PROCEDURE No loop compensation required The IS31LT3948 DEMO Board is fully assembled and Internal over-voltage protection tested. Follow the steps listed below to verify board Internal over-temperature protection operation. Caution: Do not turn on the power supply until all connections QUICK START are completed. 1) Connect the terminals of the power supply to the 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. Note: The maximum output current is determined by V /V OUT IN ratio as well as the external components. If output current and Figure 1: Photo of IS31LT3948 Evaluation Board V /V ratio is high, high current components of inductor and OUT IN NMOS are needed. ORDERING INFORMATION Part No. Temperature Range Package IS31LT3948-GRLS4-EB -40C ~ +125C (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.B, 01/11/2016 IS31LT3948 GENERAL DEMO BOARD GUIDE D2 L1 D6 LED+ R3 LED R1 R2 D1 D3 U1 1 5 C1 C2 VCC GATE Q1 C3 C5 VIN1 3 6 LED ADJ CS NC VIN2 2 8 Toff OVP LED- R7 DS C4 4 7 Q2 R4 GND FB R5 R6 R10 D5 D4 R11 NC IS31LT3948 R9 R8 PWM Figure 2: IS31LT3948 General DEMO Board Schematic BILL OF MATERIALS Name Symbol Description Qty Supplier Part No. LED Driver U1 LED Driver 1 Lumissil IS31LT3948 Resistor R1 RES,2.4K,1/8W,5%,SMD 1 YAGEO RC1206JR-072K4L Resistor R3 RES,430K,1/10W,1%,SMD 1 YAGEO RC0805FR-07430KL Resistor R4 RES,24K,1/10W,1%,SMD 1 YAGEO RC0805FR-0724KL Resistor R5,R6 RES,0.27R,1/8W,1%,SMD 2 YAGEO RL1206FR-070R27L Resistor R7 RES,10K,1/8W,1%,SMD 1 YAGEO RC1206FR-0710KL Resistor R8,R9 RES,1R8,1/8W,1%,SMD 2 YAGEO RC1206FR-071R8L RES,0R,1/8W,1%,SMD Resistor R10 (As PWM Dimming, R10 1 YAGEO RL1206FR-070R0L must be removed) Diode D1,D4 RES,0R,1/8W,1%,SMD 2 YAGEO RL1206JR-070R0L Capacitor C1 CAP,220F,35V,20%,IND 2 Rubycon 35ZLH220MEFCM8X11.5 Capacitor C3 CAP,220F,50V,20%,IND 1 Rubycon 50YXG220MEFC10X16 Capacitor C4 CAP,10F,25V,10%,SMD 1 YAGEO CC12006JKX7R8BB106 R2,C2,C5, Not installed 6 R11,D3,D5 Schottky SS26,2A,60V,DO-214AA D2,D6 2 Diodes SS26-E3 Diode SMB 1N4007,1A,1000V,D0-214AA Diode DS 1 Diodes S1MB-13 SMB Wrth Inductor L1 100H, 20%,Isat=3.1A 1 7447709271 Elektronik 2.1A, 55V, NMOS, SOT-23-3 (The default is not installed. NMOS Q2 1 AO AO3422 As PWM Dimming, Q2 must be installed.) 10A,100V,13N10L,NMOS, NMOS Q1 1 Fairchild FQD13N10LTM TO-252-3 Note: To achieve PWM dimming, the Q2 and R11 is necessary. Use 0 resistor at R11 and remove R10. Lumissil Microsystems www.lumissil.com 2 Rev.B, 01/11/2016