基于LTC3731H的三相DC稳压电源控制设计方案

Linear 公司的LTC3731H是三相同步降压开关稳压电源控制器,能驱动所有的外接功率N-MOSFET,额定工作温度高达140度C.三相控制器每相的工作频率高达600kHz,三相输出有120度相移,三相电流匹配度+/-5%,VREF在140度C内精度为+/-2%,主要用在汽车电子和工业电源,大电流输出的DC/DC电源.本文介绍LTC3731H主要特性,方框图以及典型应用电路,包括大电流55A三相降压转换器电路图, 三相65A电源电路图,2.5V/100A电源电路图和三相50V/3A升压转换器电路图.

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应用:

■ Automotive and Industrial Power Supplies

■ High Output Current DC/DC Power Supplies

图1.LTC3731H方框图

图2.LTC3731H大电流三相降压转换器电路图

图3.LTC3731H三相65A电源电路图

图4.LTC3731H 2.5V/100A电源电路图

图5.LTC3731H三相50V/3A升压转换器电路图