原标题：IR IR3859全集成效率95%DC-DC同步降压电源解决方案

　　IR 公司的IR3859是全集成效率95%DC-DC同步降压稳压器,MOSFET和PWM控制器同封在单个封装内,开关频率从250kHz到1.5MHz可编程,效率大于95%,输入电压从1.5V到21V,输出电压从0.7V到0.9xVin.可连续提供9A负载电流,主要用在服务器,存储设备,嵌入通信系统,POL电源,网络通信,计算机外设电源和通用DC/DC转换器.本文介绍了IR3859主要特性,方框图, 典型应用框图, 输入12V,输出1.8V/9A POL转换器应用电路及其材料清单,以及IR3859 评估板主要特性, 评估板电路图和材料清单.

　　The IR3859 SupIRBuckTM is an easy-to-use, fully integrated and highly efficient DC/DC synchronous Buck regulator. The MOSFETs copackaged with the on-chip PWM controller make IR3859 a space-efficient solution, providing accurate power delivery for low output voltage applications.IR3859 is a versatile regulator which offers programmability of start up time, switching frequency and current limit while operating in wide input and output voltage range.

　　The switching frequency is programmable from 250kHz to 1.5MHz for an optimum solution.It also features important protection functions, such as Pre-Bias startup, hiccup current limit and thermal shutdown to give required system level security in the event of fault conditions.

　　IR3859主要特性:

　　• Greater than 95% Maximum Efficiency

　　• Wide Input Voltage Range 1.5V to 21V

　　• Wide Output Voltage Range 0.7V to 0.9*Vin

　　• Continuous 9A Load Capability

　　• Integrated Bootstrap-diode

　　• High Bandwidth E/A for excellent transient performance

　　• Programmable Switching Frequency up to 1.5MHz

　　• Programmable Over Current Protection

　　• Over Voltage Protection

　　• Dedicated input for output voltage monitoring

　　• Programmable PGood output

　　• Hiccup Current Limit

　　• Precision Reference Voltage (0.7V, +/-1%)

　　• Programmable Soft-Start

　　• Enable Input with Voltage Monitoring Capability

　　• Enhanced Pre-Bias Start-up

　　• Seq input for Tracking applications

　　• External Synchronization

　　• -40oC to 125oC operating junction temperature

　　• Thermal Protection

　　• 4mm x 5mm Power QFN Package

　　• Halogen Free, Lead Free and RoHS compliant

　　IR3859应用:

　　• Server Applications

　　• Storage Applications

　　• Embedded Telecom Systems

　　• Distributed Point of Load Power Architectures

　　• Netcom Applications

　　• Computing Peripheral Voltage Regulators

　　• General DC-DC Converters

　　图1.IR3859简化方框图

　　图2.IR3859典型应用框图

　　图3.IR3859应用电路图:输入12V,输出1.8V/9A POL转换器

　　应用电路材料清单(BOM):

　　IR3859 评估板主要特性:

　　• Vin = +12V (13.2V Max)

　　• Vcc=+5V (5.5V Max)

　　• Vout = +1.8V @ 0- 9A

　　• Fs=600kHz

　　• L= 0.68uH

　　• Cin= 4x10uF (ceramic 1206) + 330uF (electrolytic)

　　• Cout= 6x22uF (ceramic 0805)

　　图4.IR3859 评估板外形图

　　IR3859 评估板材料清单: