原标题：Linear LTC3787大功率高效多相同步升压控制方案

　　Linear 公司的LTC3787是大功率高效多相同步升压控制器，效率高达97%，因而不需要散热器。 LTC3787集成了两个N-沟功率MOSFET，两相工作降低了输入和输出电容以及电源所引起的噪音，输电电压从4.5V到38V，输出电压高达 60V，输出电流可高达10A，可以配置成2/3/4/6/12相工作，主要用在工业，汽车，医疗和军用设备。本文介绍了LTC3787主要特性，方框图，2/3/4/6/12相工作配置图以及12-24V/10A两相同步升压转换器和高效四相单输出升压转换器等多种应用电路。

　　LTC3787: High Power Polyphase® Synchronous Boost Controller Eliminates Heat Sink with 97% Efficiency

　　The LTC®3787 is a high performance PolyPhase® single output synchronous boost converter controller that drives two N-channel power MOSFET stages out-of-phase. Multiphase operation reduces input and output capacitor requirements and allows the use of smaller inductors than the single-phase equivalent. Synchronous rectification in­creases efficiency, reduces power losses and eases thermal requirements, enabling high power boost applications.

　　A 4.5V to 38V input supply range encompasses a wide range of system architectures and battery chemistries. When biased from the output of the boost converter or another auxiliary supply, the LTC3787 can operate from an input supply as low as 2.5V after start-up. The operat­ing frequency can be set for a 50kHz to 900kHz range or synchronized to an external clock using the internal PLL. PolyPhase operation allows the LTC3787 to be configured for 2-, 3-, 4-, 6- and 12-phase operation.

　　The SS pin ramps the output voltage during start-up. The PLLIN/MODE pin selects Burst Mode® operation, pulse-skipping mode or forced continuous mode at light loads.

　　LTC3787主要特性:

　　2-Phase Operation Reduces Required Input and Output Capacitance and Power Supply Induced Noise

　　Synchronous Operation for Highest Efficiency and Reduced Heat Dissipation

　　Wide VIN Range: 4.5V to 38V (40V Abs Max) and Operates Down to 2.5V After Start-Up

　　Output Voltage Up to 60V

　　±1% 1.200V Reference Voltage

　　RSENSE or Inductor DCR Current Sensing

　　100% Duty Cycle Capability for Synchronous MOSFET

　　Low Quiescent Current: 135μA

　　Phase-Lockable Frequency (75kHz to 850kHz)

　　Programmable Fixed Frequency (50kHz to 900kHz)

　　Power Good Output Voltage Monitor

　　Low Shutdown Current, IQ < 8μA

　　Internal LDO Powers Gate Drive from VBIAS or EXTVCC

　　Thermally Enhanced Low Profile 28-Pin 4mm × 5mm QFN Package and Narrow SSOP Package

　　LTC3787应用:

　　Industrial

　　Automotive

　　Medical

　　Military

　　图1.LTC3787方框图

　　图2.LTC3787 12-24V/10A两相同步升压转换器

　　图3.LTC3787 三相工作框图

　　图4.LTC3787 四相工作框图

　　图5.LTC3787 六相工作框图

　　图6.LTC3787 十二相工作框图

　　图7.LTC3787 推荐PCB布局框图

　　图8.LTC3787 高效二相24V升压转换器

　　图9.LTC3787 高效二相28V升压转换器

　　图10.LTC3787 高效二相48V升压转换器

　　图11.LTC3787 带电感DCR电流检测的高效二相24V升压转换器