IR 公司的IR3859是全集成效率95%DC-DC同步降壓穩壓器,MOSFET和PWM控制器同封在單個封裝內,開關頻率從250kHz到1.5MHz可編程,效率大于95%,輸入電壓從1.5V到21V,輸出電壓從0.7V到0.9xVin.可連續提供9A負載電流,主要用在服務器,存儲設備,嵌入通信系統,POL電源,網絡通信,計算機外設電源和通用DC/DC轉換器.本文介紹了IR3859主要特性,方框圖, 典型應用框圖, 輸入12V,輸出1.8V/9A POL轉換器應用電路及其材料清單,以及IR3859 評估板主要特性, 評估板電路圖和材料清單.

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應用:

• Server Applications

• Storage Applications

• Embedded Telecom Systems

• Distributed Point of Load Power Architectures

• Netcom Applications

• Computing Peripheral Voltage Regulators

• General DC-DC Converters

圖1.IR3859簡化方框圖

圖2.IR3859典型應用框圖

圖3.IR3859應用電路圖:輸入12V,輸出1.8V/9A POL轉換器
應用電路材料清單(BOM):

IR3859 評估板主要特性:

• 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)

圖4.IR3859 評估板外形圖

圖5.IR3859 評估板電路圖
IR3859 評估板材料清單: