Analogic AAT1145手提电源解决方案

研诺逻辑(Analogic)科技有限公司的1.5MHz固定频率电流模式PWM降压转换器AAT1145能从单颗锂离子电池中提供高达1.2A的电流,效率依然维持在90%以上.低压降应用时占空比为100%.采用小型3x3mm TDFN封装, 无需外部补偿组件，同时为设计人员提供高度紧凑、简单易用的解决方案。广泛应用在手机,数码相机,PDA,手提仪表,智能手机以及DSP内核电源.本文提供了它的主要性能,方框图以及可调输出和固定输出的应用电路图.

The AAT1145 SwitchReg™ is a 1.5MHz constant frequency current mode PWM step-down converter. It is ideal for portable equipment requiring very high current up to 1.2A from single-cell Lithium-ion batteries while still achieving over 90% efficiency
during peak load conditions. The AAT1145 also can run at 100% duty cycle for low dropout operation, extending battery life in portable systems while light load operation provides very low output ripple for noise sensitive applications.

The AAT1145 can supply up to 1.2A output load current from a 2.5V to 5.5V input voltage and the output voltage can be regulated as low as 0.6V. The high switching frequency minimizes the size of external components while keeping switching losses low. The internal slope compensation setting allows the device to operate with smaller inductor values to optimize size and provide efficient operation.
The AAT1145 is available in adjustable (0.6V to VIN) and fixed (1.8V) output voltage versions. The device is available in a Pb-free, 3x3mm 10-lead TDFN package and is rated over the -40°C to +85°C temperature range.

主要特性:

Input Voltage Range: 2.5V to 5.5V
Output Voltages from 0.6V to VIN
1.2A Output Current
High Efficiency: Up to 95%
1.5MHz Constant Switching Frequency
Low RDS(ON) Internal Switches: 0.15Ω
Allows Use of Ceramic Capacitors
Current Mode Operation for Excellent Line and Load Transient Response
Short-Circuit and Thermal Fault Protection
Soft Start
Low Dropout Operation: 100% Duty Cycle
Low Shutdown Current: ISHUTDOWN < 1μA
TDFN33-10 Package
-40°C to +85°C Temperature Range

应用:
Cellular Phones
Digital Cameras
DSP Core Supplies
PDAs
Portable Instruments
Smart Phones



图1.AAT1145方框图.



图2.可调输出基本应用电路图.



图3.固定输出基本应用电路图.