SP6655EB Evaluation Board Manual High Efficiency Synchronous Step-Down Converter with up to 98% efficiency 400mA Output Current, only 20uA Quiescent Current 2.7V-6.5V Input Voltage range, Output Adjustable down to 0.8V DFN Package & Ceramic Capacitors for small, low profile Power Supply Ideal for PDAs, Digital Cameras, Wireless Modems, Cellular Telephones DESCRIPTION The SP6655 Evaluation Board is designed to help the user evaluate the performance of the SP6655 for use as a single Li-Ion battery Step-Down DC-DC Converter. The SP6655 operates from 2.7V to 6.5V input, with the highest efficiency in the range 3.0V to 4.2V where the Li-Ion battery has the most energy. The SP6655EB evaluation board is a complete power supply circuit to provide ease of evaluation for the DC/DC Converter performance. FIGURE 1. SP6655 1.8V OUTPUT EVALUATION BOARD SCHEMATIC Vin = 2.7V to 5.0V CIN 10uF RVIN 10.0 U1 SP6655 Vout = 1.8V BLON L1 10uH 1 10 PVin LX 2 9 Vin PGND RF 1 3 8 CF 249K BLON GND 22pF 2 4 7 D1 D1 Vout 3 5 6 COUT D0 FB 10uF RI 1 200K 2 CVIN D0 1.0uF 3USING THE EVALUATION BOARD 1) Powering up the SP6655 Circuit & Programming the UVLO threshold The SP6655 Evaluation Board can be powered from a single Li-Ion battery or a +2.7 to +5.0V power supply. Connect with short leads directly to the Vin and Gnd posts. Note the SP6655 will remain in shutdown until D0 or D1 of the Jumpers J1 or J2 are applied to the Vin or position 1 to 2. See Table 1 for UVLO threshold programming and D1 and D0 pin definition. Table 1. Operating Mode Definition D1 D0 Definition 00 Shutdown. All internal circuitry is disabled and the power switches are opened. 01 Device enabled, falling UVLO threshold = 2.70V 10 Device enabled, falling UVLO threshold = 2.85V 11 Device enabled, falling UVLO threshold = 3.00V 2) VOUT PROGRAMMING The SP6655 requires 2 feedback resistors to control the output voltage. Connect the appropriate resistors RF and RI (Table 2) from pin 6 SP6655 FB to Vout and to the GND. For Vout different from that shown in the Table 2, use equation: Vout RF = 1 RI 0.8 Table 2. SP6655UEB BILL OF MATERIALS Component Vo = 1.8V L1 10uH, Murata LQH32CN100K11, 0.3ohm, 0.45A, 1210 CIN 22uF, TDK C2012X5R0J106M, 0.005ohm, 6.3V, X5R, 0805 COUT 22uF, TDK C2012X5R0J106M, 0.005ohm, 6.3V, X5R, 0805 RVIN 10 Ohm 5%, 0603 CVIN 1uF, TDK C1608X5R0J105M, 0.03ohm, .3V, X5R, 0603 RI 200k 1%, 0603 RF 249k 1%, 0603 CF 22pF ceramic, 0603 U1 SP6655ER, 10 pin DFN