EV0056 Fixed Frequency White LED Driver Monolithic Power Systems General Description EVALUATION BOARD Absolute Maximum Ratings The EV0056 evaluation board is designed for backlights using white LEDs. It implements MPS’ MP1518 fixed frequency step-up converter. The MP1518 is a 6 pin thin SOT23 step up converter designed for driving up to 6 series white LEDs from a single cell Lithium Ion battery. The MP1518 uses current mode, fixed frequency architecture to regulate the LED current, which is measured through an external current sense resistor. It’s low 100mV feedback voltage reduces power loss and improves efficiency. To prevent damage due to an open circuit condition, the OV pin monitors the output voltage and turns off the converter if an over-voltage condition is present. The MP1518 includes under-voltage lockout, current limiting and thermal overload protection preventing damage in the event of an output overload. The MP1518 is available in a small 6 lead TSOT23 package. SW -0.5V to 28V All Other Pins except OV -0.3V to 6.5V Recommended Operating Conditions IN Supply Voltage 2.5V to 6V Features On Board Power MOSFET Drives up to 6 Series White LEDs Up to 86% Efficiency Over 1MHz Fixed Switching Frequency Open Load Shutdown Low 100mV Feedback Voltage Soft Start/PWM Dimming UVLO, Thermal Shutdown Internal Current Limit Applications Cell Phones Handheld Computers and PDAs Digital Still and Video Cameras Small LCD Displays Ordering Information Board Number MPS IC Number EV0056 MP1518DJ Figure 1: EV0056 Evaluation Board Actual Size = 1.9”X x 1.8”Y EV0056 1.0_08/01/03 Monolithic Power Systems, Inc. 1 EV0056 Fixed Frequency White LED Driver Monolithic Power Systems EVALUATION BOARD Figure 2: EV0056 Schematic TP2 L1 D1 VIN B0530WS/B0530W C1 LED1 R1 LED2 TP1 EN LED3 GND TP3 LED4 C2 LED5 LED6 EV0056 / MP1518 Evaluation Board R2 ev0056_MP1518_rev_B.sch 8/01/03 Table 1: EV0056 Bill of Materials Component Description Manufacturer Part Number Package Qty U1 C1 C2 D1 L1 R1 R2 LED1 – LED6 White LED Driver 2.2µF, 10V, X7R 0.22µF, 25V, X7R Schottky Diode 22µH Inductor 100KΩ 5.1Ω White LED MP1518DJ ANY ANY B0530WS/B0530W TOKO D31FB 984FB-220M ANY ANY ANY SOT23-6 0805 0805 SOD323 SMD 0603 0603 1210 1 1 1 1 1 1 1 NS Total 7 *NS = No Stuff EV0056 1.0_08/01/03 Monolithic Power Systems, Inc. 2 EV0056 Fixed Frequency White LED Driver Monolithic Power Systems EVALUATION BOARD Board Operation: 1. Solder LED1 – LED6 to board. 2. Connect positive and negative terminals of 2.5V to 6V power supply to VIN and GND pins respectively. 3. Drive EN high to turn on the MP1518, drive EN low to shut down the MP1518. 4. To use burst-mode brightness control, drive EN with a PWM signal. Figure 3: Top Silk Layer Figure 4: Top Layer Figure 5: Bottom Silk Layer Figure 6: Bottom Layer NOTICE: MPS believes the information in this document to be accurate and reliable. However, it is subject to change without notice. Please contact the factory for current specifications. No responsibility is assumed by MPS for its use or fit to any application, nor for infringement of patent or other rights of third parties. EV0056 Rev 1.0 08/01/03 © 2003 MPS, Inc. Monolithic Power Systems, Inc. 983 University Ave, Building D, Los Gatos, CA 95032 USA Tel: 408-395-2802 ♦ Fax: 408-395-2812 ♦ Web: www.monolithicpower.com 3