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