PAM2805 EVB User Guide PAM2805 SOT23-6 EV Board User Guide AE Department 1. Revision Information Date 2011/11 Revision V1.0 Description Initial Release Comment 2. PAM2805 General Description The PAM2805 is a step-up DC-DC WLED driver with 3 modes cycling function (100%brightness, 25%brightness and 8.5Hz blinking). The unique 3 modes cycling function can eliminate the needs of extra functional MCU or IC. The PAM2805 can deliver up to 750mA output current by setting an external resistor. The PAM2805 switches at a 1.0MHz constant frequency, allowing for the use of small value external inductor and ceramic capacitors. A low 95mV feedback voltage reduces the power loss in the Rs for better efficiency. With its internal 2A, 100mΩ NMOS switch, device can provide high efficiency even at heavy load. The PAM2805 is available in SOT23-6 package. 3. Key Features z 3 Modes Cycling Function: Power Off Power Off < 5s < 5s Bright Dimming Blinking Power Off < 5S z Reset to Bright mode if Power Off time more than 5S z Adjustable Output Current: up to z 8.5Hz Blinking Mode z Low Start-Up Voltage: 0.9V(Typ.) z Low SW on Resistance: 100mΩ z Over Temperature Protection z Over Voltage Protection z SOT23-6 Package z Pb-Free Package 750mA This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice. No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product. PAM2805 EVB User Guide 4. EV Board Schematic Vin D1 Vo 6 L1 Cin 3 Vin BLK GND 1 SW IC1 FB 5 4 WLED Co FB Rs 2 C1 Vout 5. EVB PAM2805 Description PAM2805 EVB is an evaluation board for the PAM2805 SOT23-6, a WLED driver. The board is targeted to be used in providing a simple and convenient evaluation environment for the PAM2805. Requires parts, power supply connectors etc. on the board, which makes it easy to be evaluated. This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice. No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product. PAM2805 EVB User Guide 6. EV Board View EV board operational sequence: 1. Connect LED+ to anode of the power LED, the cathode connect to LED2. Connect Vin and GND to power supply. 7. Resistor Select for LED Current Setting ILED = VREF/RS ILED 350mA 750mA (VREF = 0.095V; RS =RS1//RS2) Rs1 0.27Ω 0.27Ω Rs2 NC 0.22Ω This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice. No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product. PAM2805 EVB User Guide 8. External Components Selection Input & output Capacitors (Cin, Co) (1) For lower output ripple, low ESR is required. (2) Low leakage current needed, 10uF, X5R/X7R ceramic recommend. Blinking Capacitors (C1) (1) Low leakage current needed, 1uF, X5R/X7R ceramic recommend. Iset resistors (Rs1, Rs2) (1) RS set the power LED current, ILED=0.095V/RS, RS= RS1// RS2, See above table (2) For accurate LED Current 1% tolerance is required. (3) Pay attention to power dissipation to these resistors for flowed high current. Inductor (L1) (1) Low DCR for good efficiency (2) Inductor rated current must higher than the output current Diode (D1) (1) Consult the input voltage range and the output current, SS22 recommend 9. External Board BOM List Item Value Cin 10µF Co(1) 10µF C1 1uF Rs1 L1 D1 IC1 PCB 0.27Ω 2.2µH Note: Type X5R/X7R, Ceramic/0805 X5R/X7R, Ceramic/0805 X5R/X7R, Ceramic/0603 0805 2A/20V PAM2805 PAM2805 EVB Rating 10V 10V 25V 1% >2A Description Vender and Part No. TAIYO YUDEN Input coupling CAP, EMK212ABJ106KD-T TAIYO YUDEN Output CAP EMK212ABJ106KD-T TAIYO YUDEN Blinking CAP, TMK107 BJ105KA-T LED current set RES Inductor CD43-2.2uH Schottky Diode SS22 SOT23-6 1. For single cell application, It will be much better to add a 10µF output CAP to improve the efficiency. This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice. No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product. PAM2805 EVB User Guide 10. PCB Layout Example Top Layer Bottom Layer This application note contains new product information. Diodes, Inc. reserves the right to modify the product specification without notice. No liability isassumed as a result of the use of this product. No rights under any patent accompany the sale of the product.