基于LTC3731H的三相DC穩壓電源控制設計方案

Linear 公司的LTC3731H是三相同步降壓開關穩壓電源控制器,能驅動所有的外接功率N-MOSFET,額定工作溫度高達140度C.三相控制器每相的工作頻率高達600kHz,三相輸出有120度相移,三相電流匹配度+/-5%,VREF在140度C內精度為+/-2%,主要用在汽車電子和工業電源,大電流輸出的DC/DC電源.本文介紹LTC3731H主要特性,方框圖以及典型應用電路,包括大電流55A三相降壓轉換器電路圖, 三相65A電源電路圖,2.5V/100A電源電路圖和三相50V/3A升壓轉換器電路圖.

The LTC?3731H is a PolyPhase? synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a phase-lockable fixed frequency architecture. The LTC3731H is rated for operation up to 140 degree C junction temperature. The 3-phase controller drives its output stages with 120 degree ?phase separation at frequencies up to 600kHz per phase to minimize the RMS current losses in both the input and output filter capacitors. The 3-phase technique effectively triples the fundamental frequency, improving transient response while operating each controller at an optimal frequency for efficiency and ease of thermal design. Light load efficiency is optimized by using a choice of output Stage Shedding or Burst Mode operation.

The precision reference supports output voltages from 0.6V to 6V. Current foldback provides protection for the external MOSFETs under short-circuit or overload conditions.Please refer to the LTC3731 data sheet for 0 C to 70 C and
–40 C to 85 C rated versions.

LTC3731H主要特性:

■ 3-Phase Current Mode Controller with Onboard MOSFET Drivers

■ 5% Output Current Matching Optimizes Thermal Performance and Size of Inductors and MOSFETs

■ 2% VREF Accuracy Over Temperature up to 140 C

■ Reduced Power Supply Induced Noise

■ 10% Power Good Output Indicator

■ 250kHz to 600kHz Per Phase, PLL, Fixed Frequency

■ PWM, Stage SheddingTM or Burst Mode? Operation

■ OPTI-LOOP? Compensation Minimizes COUT

■ Adjustable Soft-Start Current Ramping

■ Short-Circuit Shutdown Timer with Defeat Option

■ Overvoltage Soft Latch

■ Adjustable Undervoltage Lockout Threshold

■ Selectable Phase Output for Up to 12-Phase Operation

■ Available in 36-Pin Narrow (0.209") SSOP Package

LTC3731H應用:

■ Automotive and Industrial Power Supplies

■ High Output Current DC/DC Power Supplies

圖1.LTC3731H方框圖

圖2.LTC3731H大電流三相降壓轉換器電路圖

圖3.LTC3731H三相65A電源電路圖

圖4.LTC3731H 2.5V/100A電源電路圖

圖5.LTC3731H三相50V/3A升壓轉換器電路圖