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SP6654EB Evaluation Board Manual High Efficiency Synchronous Step-Down Converter with up to 98% efficiency 800mA Output Current, only 20uA Quiescent Current 2.7V-6.5V Input Voltage range, Output Adjustable down to 0.8V SOIC Package & DFN Ceramic Capacitors for small, low profile Power Supply DESCRIPTION The SP6654 Evaluation Board is designed to help the user evaluate the performance of the SP6654 for use as a single Li-Ion battery Step-Down DC-DC Converter. The SP6654 operates from 2.7V to 5.5Vinput, with the highest efficiency in the range 3.0V to 4.2V where the Li-Ion battery has the most energy. The SP6654EB evaluation board is a complete power supply circuit to provide ease of evaluation for the DC/DC Converter performance. FIGURE 1. SP6654 3.3V OUTPUT EVALUATION BOARD SCHEMATIC Vin 2.7 - 5.5VDC CIN 22uF RVIN 10.0 1 2 1 3 4 5 PWRGD U1 SP6654 PVin Vin LX PGND 10 9 8 7 6 L1 10uH Vout 3.3V 800mA RF 825K PWRGD GND D1 D0 Vout FB D1 2 3 1 CF 22pF COUT 22uF RI 261K D0 2 3 CVIN 1.0uF Date: 02/18/05 SP6654 Evaluation Board Manual Copyright Sipex Corporation FIGURE 2. SP6654 1.5V OUTPUT EVALUATION BOARD SCHEMATIC Vin 2.7 - 5.5VDC CIN 22uF RVIN 10.0 1 2 1 3 4 5 PWRGD U1 SP6654 PVin Vin LX PGND 10 9 8 7 6 L1 10uH Vout 1.5V 800mA RF 226K PWRGD GND D1 D0 Vout FB D1 2 3 1 CF 22pF COUT 22uF RI 261K D0 2 3 CVIN 1.0uF USING THE EVALUATION BOARD 1) Powering up the SP6654 Circuit & Programming the UVLO threshold The SP6654 Evaluation Board can be powered from a single Li-Ion battery or a +2.7 to +5.5V power supply. Connect with short leads directly to the "Vin" and "Gnd" posts. Note the SP6654 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 0 0 1 1 D0 0 1 0 1 Definition Shutdown. All internal circuitry is disabled and the power switches are opened. Device enabled, falling UVLO threshold = 2.70V Device enabled, falling UVLO threshold = 2.85V Device enabled, falling UVLO threshold = 3.00V 2) VOUT PROGRAMMING The SP6654 requires 2 feedback resistors to control the output voltage. Connect the appropriate resistors RF and RI (Table 2) from pin 6 SP6654 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 2 Table 2. SP6654EB BILL OF MATERIALS Component L1 CIN COUT RVIN CVIN RI RF CF U1 Vo = 3.3V Vo = 1.5V 10uH, CDRH5D28-100, Sumida 10uH, CDRH5D28-100, Sumida 22uF, TDK C3225X5R0J226M 22uF, TDK C3225X5R0J226M 10 Ohm 5% 1uF ceramic X7R SM 0805 261k 1% 825k 1% 22pF ceramic SP6654EU or SP6654ER 22uF, TDK C3225X5R0J226M 22uF, TDK C3225X5R0J226M 10 Ohm 5% 1uF ceramic X7R SM 0805 261k 1% 226k 1% 22pF ceramic SP6654EU or SP6654ER Table 3. SP6654 PIN ASSIGNMENT Pin Name PVin Vin PWRGD D1 D0 Pin Description Input voltage power pin. Inductor charging current passes through this pin. Internal supply voltage. Control circuitry powered from this pin. Open drain battery low output - need to pullup to supply externally. Vout below threshold pulls this node to ground. Vout above threshold, this node is open. Digital mode control input. See Table 1 for definition. Digital mode control input. See Table 1 for definition. 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. Output voltage sense pin. Used for internal timing and BLON circuitry. Internal ground pin. Control circuitry returns current to this pin. 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. Pin NO. 1 2 3 4 5 FB 6 Vout GND PGND LX 7 8 9 10 3 EVALUATION BOARD LAYOUT FIGURE 3: SP6654EB COMPONENT PLACEMENT FIGURE 4: SP6654EB PC LAYOUT TOP SIDE FIGURE 5: SP6654EB PC LAYOUT BOTTOM SIDE 4 |
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