双输出多相电流模式同步控制方案

电子工程师 2019-08-04 3122

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描述

ADI公司的LTCR7852/LTC7852-1是6相双输出电流模式同步降压开关稳压器控制器，和外接功率器件如DrMOS，功率区块或分立N沟MOSFET和相关的栅极驱动器。它可以进行1-，2-，3-，4-，5-和6相配置。采用两个IC并联可配置成8-，10和12相，以得到高达400A电流。亚毫欧姆DCR检测或DrMOS电流检测改善了效率，总输出电压精度±0.5%，具有灵活的相位配置和双输出电流监视，双差分遥测放大器，可编频率范围从250kHz到1.2MHz，VIN范围不受IC所限，VCC范围4.5V-5.5V，VOUT范围从0.5V到2.0V.主要用在计算机系统，通信和数据系统以及DC电源分布系统。本文介绍了LTC7852-1主要特性，功能框图，典型应用电路和多种应用电路，以及演示板DC2631A主要特性，框图，测试建立图，以及电路图，材料清单和PCB设计图。

The LTCR7852/LTC7852-1 is a six-phase， dual outputcurrent mode synchronous step-down switching regulatorcontroller that works in conjunction with externalpower train devices such as DrMOS， power blocks ordiscrete N-channel MOSFETs and associated gate drivers.

Its flexible design enables 1-， 2-， 3-， 4-， 5-， and 6-phaseconfigurations. The LTC7852 offers a unique feature thatenhances the signal-to-noise ratio of the current sensesignal， allowing the use of inductors with very low DCwinding resistances for maximum efficiency. The controllerachieves a minimum on-time of just 40ns， permitting theuse of high switching frequency at high step-down ratios.

8-， 10- or 12 phases with two ICs can be paralleled forvery high current requirements up to 400A.The remote sense differential amplifiers and a precisereference provide accurate output voltages between 0.5Vand 2.0V. The input voltage is not limited by the controller. Hiccup mode protection from output shorts or overcurrentminimizes the thermal dissipation.

The LTC7852-1 is designed specifically for DrMOS withan internal current sense signal.

LTC7852-1主要特性：

Sub-Milliohm DCR Sensing or DrMOS with CurrentSense Improves Efficiency

Operates with Power Blocks， DrMOS or ExternalGate Drivers and MOSFETs

±0.5% Total Output Voltage Accuracy

Flexible Phase Configuration

Dual Output Current Monitoring

tON（MIN） = 40ns， Capable of Very Low Duty Cycles atHigh Frequency

Dual Differential Remote Sensing Amplifiers

Programmable Frequency Range of 250kHz to 1.2MHz

VIN Range Is Not Limited by IC

VCC Range： 4.5V to 5.5V

VOUT Range： 0.5V to 2.0V

48 Lead （5mm × 6mm） GQFN for LTC7852

36 Lead （4mm × 5mm） QFN for LTC7852-1

LTC7852-1应用：

Computer Systems

Telecom and Datacom Systems

DC Power Distribution Systems

电流模式

图1.LTC7852-1典型应用电路

电流模式

图2.LTC7852-1功能框图

电流模式

图3.带分立驱动器和MOSFET的LTC7852单输出6相1V/200A转换器电路

电流模式

图4.带DRMOS的LTC7852双输出4相0.9V/120A和2相1.2V/60A转换器电路

演示板DC2631A

Demonstration circuit 2631A features the LTC®7852 in two high output current， high efficiency step down converters each with its own assembly type. The converter for the -A assembly provides two 3-phase outputs of 1.0V/100A and 1.5V/100A. The -B assembly provides a single 6-phase 1.0V/200A output. Block diagrams are shown in Figure 3. Both converters operate over a 7V to 14V input voltage range at a switching frequency of 400kHz.

The power stage for each phase consists of a 5mm × 5mm DrMOS and 11.3mm × 11.0mm 0.25μH ferrite inductor with a DCR of 0.32mΩ typical. The LTC7852 employs a peak current mode architecture which allows accurate DCR sensing and sharing with sub-mOhm DCR inductors. The LTC7852 provides a three-state compatible PWM output for each DrMOS.

演示板DC2631A主要特性：

Additional features of the DC2631A include：

lDifferential sensing for the output voltages of VOUT1 and VOUT2

lIMON pins to monitor the inductor current of each rail.

l Optional resistors and jumpers to change the phase arrangement for VOUT1 and VOUT2：

q VOUT1： 4ph， VOUT2： 2ph

q VOUT1： 5ph， VOUT2： 1ph

q Note， the default arrangement is： VOUT1： 3ph， VOUT2： 3ph

l Optional resistors and jumpers to parallel VOUT1 and VOUT2.

l RUN， PGOOD， PLLIN and CLKOUT pins

The LTC7852 data sheet provides a complete description of the IC operation and application information. The data sheet must be read in conjunction with the quick start guide.

电流模式