General Description

The SY20518 is a 2.6V to 5.5V input voltage range, high

efficiency, fixed frequency Buck-Boost converter that can

provide up to 2A of continuous current to a load that

requires a voltage below equal or above the input voltage.

The converter can provide power for system powered by

either a two-cell or three-cell alkaline, Ni-Cd or Ni-MH

batteries, or a single cell Li-Ion or Li-polymer battery.

The SY20518 is based on a fixed frequency, pulse-widthmodulation (PWM) controller using synchronous

rectification to obtain maximum efficiency. The output

voltage and compensation circuit can be programmed

using an external RC network.

The part automatically transitions to PFM mode under light

load conditions, to maintain high efficiency across the

entire load range.

During shutdown, the load is disconnected from the

battery and the part only consumes 0.1μA of current (typ.).

The device is available in a 2 mm ×3 mm QFN package.

特性 Features

? 2.6V to 5.5V Input Voltage Range

? 2A Continuous Output Current Capability

? Adjustable Output Voltage between 2.6V and 3.8V

Independent of the Input Voltage

? 1 MHz (typ.) Fixed Frequency Operation

? Four low RDSON Internal Power Switches

? Seamless Buck-Boost Transition

? Output Disconnect During Shutdown

? Power Good Indicator

? Built In Thermal Shut Down Protection, Hard

Short Protection

Applications

? Handheld Instruments

? MP3/MP4 Players

? Digital Cameras/Camcorders

? Personal Medical Products

? High Power LED’s

? Two-cell and three-cell alkaline, Ni-Cd or Ni-MH or

single cell Li battery powered products