SP6656EB

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 1 OVSO 2 OVSI 1 3 2 4 3 5 PVin Vin LX PGND OVSO GND OVSI Vout EN 1 FB 10uH Vout = 1.8V (OVSI=L) or 2.8V (OVSI=H) 9 8 CF 120pF RF 249K 7 6 Rs 200K CVIN EN L1 10 RI 200K COUT 10uF 2 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  where RA = RI * RS RI + RS Table 1. SP6656EB BILL OF MATERIALS Component L1 CIN COUT RVIN CVIN RI RF RF CF Rev 10/17/05 Vo = 1.8V 10uH, Murata LQH32CN100K11, 0.3ohm, 0.45A, 1210 10uF, TDK C2012X5R0J106M, 0.005ohm, 6.3V, X5R, 0805 10uF, TDK C2012X5R0J106M, 0.005ohm, 6.3V, X5R, 0805 10 Ohm 5%, 0603 1uF, TDK C1608X5R0J105M, 0.03ohm, .3V, X5R, 0603 200k 1%, 0603 249k 1%, 0603 200k 1%, 0603 22pF ceramic, 0603 2 SP6655 Evaluation Board Manual Table 3. SP6656 PIN ASSIGNMENT Pin Name PVin Vin Pin NO. Pin Description Input voltage power pin. Inductor charging current passes through this pin. Internal supply voltage. Control circuitry powered from this pin. 1 2 OVSO Output Voltage Select Open Drain Output . 3 OVSI Output Voltage Select digital input. 4 EN Enable digital input. 5 FB External feedback network input connection. Connect a resistor from FB to ground and FB to Vout to control the output voltage. This pin regulates to the internal reference voltage of 0.8V. 6 Vout Output voltage sense pin. Used for internal timing circuitry. 7 GND Internal ground pin. Control circuitry returns current to this pin. 8 PGND LX Rev 10/17/05 Power ground pin. Synchronous rectifier current returns through this pin. Inductor switching node. Inductor tied between this pin and the output capacitor to create Vout. 3 9 10 SP6655 Evaluation Board Manual EVALUATION BOARD LAYOUT FIGURE 3: SP6656EB COMPONENT PLACEMENT FIGURE 4: SP6656EB PC LAYOUT TOP SIDE FIGURE 5: SP6656EB PC LAYOUT BOTTOM SIDE Rev 10/17/05 4 SP6655 Evaluation Board Manual