AN727

AN727 Vishay Siliconix High-Frequency, High-Efficiency Buck Converter Design For Multi-Cell Battery Configured Systems Using Si9167 Nitin Kalje INTRODUCTION The Si9167 is a high-frequency synchronous dc-to-dc switching buck regulator, with an operating range suitable for two-cell Li+ battery-powered applications. Capable of operation up to 2 MHz, the Si9167 can be used to supply power amplifiers and to power up baseband circuits in satellite phones. Its high operating frequency reduces the size of inductor and capacitor components, while its low on-resistance internal driver ensures maximum power conversion efficiency. Additional features include an integrated input undervoltage lockout, power on reset, integrated soft start, light load pulse skipping mode selection, synchronization, clock output for master-slave configuration of multiple regulators, uncommitted power-good comparator, and over temperature protection. An output power in excess of 2 W at 3.6 VO is possible in 0.3 square inches. TYPICAL APPLICATION CIRCUIT +VIN 5 - 10 V 1 C1 10 mF 16 V PGND 2 R1* 51 W C1 0.1 mF Si9167 ENABLE/DISABLE PWM/PSM R9* 51 kW 1 2 3 4 5 6 7 8 1.3 V C3 0.1 mF 9 10 SD PWM/PSM VIN VIN POK SYNC CLK GND VREF FB COIL COIL PGND COIL PGND POKIN VO VDD ROSC COMP R3 8.2 kW C5 1000 pF C4 56 pF 20 MBRO520T1 19 18 17 16 15 14 13 12 11 R2 75 kW D1 3.6 V @ 600 mA L1 4.7 mH IHLP2525 C1 10 mF 16 V C9 0.1 mF 7 VOUT 8 PGND R7 105 kW R8 64 kW C6 0.1 mF R4 200 W C7 330 pF R6 12.4 kW R5 22 kW STA...