原标题：Maxim MAX8655宽输入25A降压电源稳压方案

　　Maxim 公司的MAX8655 是集成功率MOSFET的宽输入25A降压电源稳压器,输入电压4.5V到25V,输出电压可在0.7V-5.5V间调整,负载电流高达25A,开关频率在200kHz到1MHz, 主要应用在POL电源,通信电源,网络通信,非隔离DC/DC电源模块,服务器和工作站,笔记本电脑和IBA电源.本文介绍MAX8655主要特性,功能方框图以及多种典型应用电路.

　　Highly Integrated, 25A, Wide-Input, Internal MOSFET, Step-Down Regulator

　　The MAX8655 synchronous-PWM buck regulator operates from a 4.5V to 25V input and generates an output voltage adjustable from 0.7V to 5.5V at loads up to 25A.Integrated power MOSFETs provide a small footprint, ease of layout, and reduced EMI. Removing the board trace inductances ensures the highest efficiency at high frequency.

　　The MAX8655 uses peak current-mode control architecture with an adjustable (200kHz to 1MHz), constantswitching frequency, which is externally synchronizable.

　　The MAX8655’s adjustable current limit uses the inductor’s DC resistance to improve efficiency or an external sense resistor for higher accuracy. Foldback type current limit is available to reduce the power dissipation under severe-overload or short-circuit conditions. A reference input is provided for use with a high-accuracy external reference or for DDR and tracking applications.

　　Monotonic startup provides safe starting into a prebiased output, where traditional step-down regulators discharge the output capacitor during soft-start, creating a negative voltage at the output and possibly damaging the load.

　　A 180° out-of-phase synchronization output is available for synchronizing with another MAX8655. An enable input is provided for on/off control and to facilitate output sequencing. Output-voltage sensing for programmable overvoltage protection is provided and is independent of the feedback network to further enhance the output overvoltage protection.

　　Overall, the MAX8655 provides enough flexibility for the experienced user, as well as simplicity and ease of use for non-power-supply engineers.

　　MAX8655主要特性:

　　_ 25A Output Current

　　_ Integrated Power MOSFETs

　　_ Operates from 4.5V to 25V Supply

　　_ 1% FB Voltage Accuracy Over Temperature

　　_ Adjustable Output Voltage Down to 0.7V

　　_ Adjustable Switching Frequency and External Synchronization from 200kHz to 1MHz

　　_ Multiphase Operation with Accurate Current Sharing

　　_ 180° Phase-Shifted Synchronization

　　_ Adjustable Overcurrent Limit

　　_ Adjustable Slope Compensation

　　_ Selectable Current-Limit Mode: Latch-Off or Automatic Recovery

　　_ Monotonic Output Voltage Rise at Startup into Prebias Output

　　_ Output Sources and Sinks Current for DDR Applications

　　_ Enable Input

　　_ Power-OK (POK) Output

　　_ Adjustable Soft-Start

　　_ Independently Adjustable Overvoltage Protection

　　MAX8655应用:

　　Point-of-Load Power Supplies

　　Telecom Power

　　Networking

　　Nonisolated DC-DC Power Modules

　　Servers and Workstations

　　Notebook Computers

　　IBA Power Supplies

　　图1.MAX8655功能方框图

　　图2.MAX8655典型应用电路图

　　图3.单相600kHz 开关, 10.8V- 13.2V 输入和1.2V/20A 输出

　　图4.单相350kHz 开关, 6V- 20V 输入和3.3V/20A 输出