原标题：TI LM5045 直流电源转换评估参考设计方案

　　TI公司的lm5045是一款可实现电流模式或电压模式的全桥式拓扑PWM功率控制转换器芯片，该芯片主要解决输入最高电压达100V的原级隔离DC-DC转换器。具有电流限制、可编程软启动、同步整流软启动和热关断等特性。本文首先介绍芯片的简介、特性及内部框图，并给出相应设计方案的设计原理图、元器件列表及PCB元件布局图。

　　The LM5045 PWM controller contains all of the features necessary to implement Full-Bridge topology power converters using either current mode or voltage mode control. This device is intended to operate on the primary side of an isolated dc-dc converter with input voltage up to 100V. This highly integrated controller-driver provides dual 2A high and low side gate drivers for the four external bridge MOSFETs plus control signals for the secondary side synchronous rectifier MOSFETs. External resistors program the leading and trailing edge dead-time between the main and synchronous rectifier control signals. Intelligent startup of the synchronous rectifiers allows monotonic turn-on of the power converter even with pre-bias load conditions.Additional features include cycle-by-cycle current limiting, hiccup mode restart, programmable soft start, synchronous rectifier soft-start and a 2 MHz capable oscillator with synchronization capability and thermal shutdown.

　　LM5045主要特性：

　　2• Highest Integration Controller for Small Form Factor, High Density Power Converters

　　• High Voltage Start-up Regulator

　　• Intelligent Sync Rectifier Start-up Allows Linear Turn-on into Pre-biased Loads

　　• Synchronous Rectifiers Disabled in UVLO mode and Hiccup Mode

　　• Two Independent, Programmable Synchronous Rectifier dead-time Adjustments

　　• Four High Current 2A Bridge Gate Drivers

　　• Wide-Bandwidth Opto-coupler Interface

　　• Configurable for either Current Mode or Voltage Mode Control

　　• Dual-mode Over-Current Protection

　　•Resistor Programmed 2MHz Oscillator

　　• Programmable Line UVLO and OVP

　　图1. LM5045内部方框图

　　LM5045方案介绍：

　　The LM5045 evaluation board is designed to provide the design engineer with a fully functional power converter based on the full-bridge topology to evaluate the LM5045 PWM controller. The evaluation board is provided in an industry standard quarter brick footprint.

　　The performance of the evaluation board is as follows:

　　• Input operating range: 36V to 75V

　　• Output voltage: 3.3V

　　• Measured efficiency at 48V: 92% @ 30A

　　• Frequency of operation: 420kHz

　　• Board size: 2.28 x 1.45 x 0.5 inches

　　• Load Regulation: 0.2%

　　• Line Regulation: 0.1%

　　• Line UVLO (34V/32V on/off)

　　• Hiccup Mode Current Limit

　　The printed circuit board consists of 6 layers; 2 ounce copper outer layers and 3 ounce copper inner layers on FR4 material with a total thickness of 0.062 inches. The unit is designed for continuous operation at rated load at <40°C and a minimum airflow of 200 LFM.

　　LM5045方案原理图：

　　图2. LM5045方案原理图

　　LM5045方案材料清单：