The S-8550 Series is a CMOS synchronous rectification step-down switching regulator which mainly consists of a reference voltage circuit, an oscillator, an error amplifier, a phase compensation circuit, a PWM controller, an under voltage lockout circuit (UVLO), a current limit circuit, and a power MOS FET. The oscillation frequency is high at 1.2 MHz, so a high efficiency, large output current, step-down switching regulator can be achieved by using small external parts.
The built-in synchronous rectification circuit makes achieving high efficiency easier compared with conventional step-down switching regulators. A ceramic capacitor can be used as an output capacitor. High-density mounting is supported by adopting packages small SOT-23-5 and super-small and thin SNT-8A.

■ Features
• Oscillation frequency: 1.2 MHz
• Input voltage range: 2.0 V to 5.5 V
• Output voltage range: Arbitrarily settable by external output voltage setting resistor
• Output current: 600 mA
• Reference voltage: 0.6 V ±2.0%
• Efficiency: 92%
• Soft-start function: 1 ms typ.
• Shutdown function: Shutdown current consumption : 1.0 μA max.
• Built-in current limit circuit
• Pch power MOS FET on-resistance: 0.4 Ω typ.
• Nch power MOS FET on-resistance: 0.3 Ω typ.
• Constant continuous mode operation (no light load mode)
• Lead-free, Sn 100%, halogen-free*1

■ Applications
• Mobile devices, such as mobile phones, Bluetooth devices, wireless devices, digital audio players, digital still cameras, portable DVD players, and portable CD players