SP6656EB Evaluation Board Manual High Efficiency Synchronous Step-Down Converter with up to 98% efficiency 400mA Output Current, only 20uA Quiescent Current 2.9V-5.5V Input Voltage range, Output Adjustable down to 1.0V Small 2.5x2.4mm DFN Package & Ceramic Capacitors for small, low profile Power Supply Ideal for PDAs, Digital Cameras, Wireless Modems, Cellular Telephones DESCRIPTION The SP6656 Evaluation Board is designed to help the user evaluate the performance of the SP6656 for use as a single Li-Ion battery Step-Down DC-DC Converter. The SP6656 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 SP6656EB evaluation board is a complete power supply circuit to provide ease of evaluation for the DC/DC Converter performance. FIGURE 1. SP6656 1.8V OUTPUT EVALUATION BOARD SCHEMATIC Vin = 2.7V to 5.0V CIN 10uF RVIN 10.0 U1 SP6656 Vout = 1.8V (OVSI=L) or 2.8V (OVSI=H) L1 10uH 1 10 OVSO PVin LX 2 9 Vin PGND RF 1 3 8 CF 249K OVSO GND 120pF 2 4 7 OVSI OVSI Vout 3 5 6 COUT EN FB 10uF RI 1 Rs 200K CVIN 200K 2 EN 1.0uF 3 USING THE EVALUATION BOARD Rev 10/17/05 SP6655 Evaluation Board Manual Copyright Sipex Corp. 1) Powering up the SP6656 Circuit The SP6656 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 SP6656 will remain in shutdown until the EN Jumper J1 is applied to the Vin or position 1 to 2. 2) VOUT PROGRAMMING The SP6656 has a dynamically programmable output voltage using the OVSI and OVSO pins. This requires 2 feedback resistors to control the output voltage as well as an Rs resistor for the dynamically programmed output voltage. Connect the appropriate resistors RF and RI (Table 1) from pin 6 SP6656 FB to Vout and to the GND. For Vout Low, select OVSI = L and use the formula below to set the output voltage: Vout RF = 1 RI 0.8 For Vout High, select OVSI = L, and the RS resistor will be switched in to change the output voltage from the previously set voltage to a larger output voltage, determined by the following equation: Vout RF = 1 RA 0.8 RI *RS where RA= RI +RS Table 1. SP6656EB BILL OF MATERIALS Component Vo = 1.8V L1 10uH, Murata LQH32CN100K11, 0.3ohm, 0.45A, 1210 CIN 10uF, TDK C2012X5R0J106M, 0.005ohm, 6.3V, X5R, 0805 COUT 10uF, 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 RF 200k 1%, 0603 CF 22pF ceramic, 0603 Rev 10/17/05 SP6655 Evaluation Board Manual 2