TI公司的LM5046是一款可實現電流模式或電壓模式的全橋式拓撲PWM功率控制轉換器芯片，該芯片主要解決輸入最高電壓達100V的原級隔離DC-DC轉換器。具有電流限制、可編程軟啟動、同步整流軟啟動和熱關斷等特性。本文首先介紹芯片的簡介、特性及內部框圖，并給出相應設計方案的設計原理圖、元器件列表及PCB元件布局圖。
The LM5046 PWM controller contains all of the features necessary to implement a Phase-Shifted Full-Bridge topology power converter 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 dead-time to enable zero-volt switching of the primary FETs. Intelligent startup of the synchronous rectifiers allows monotonic turn-on of the power converter even with pre-bias load conditions. Additional features include cycle-bycycle current limiting, hiccup mode restart,programmable soft-start, synchronous rectifier softstart and a 2 MHz capable oscillator with synchronization capability and thermal shutdown.
LM5046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
圖1. LM5046內部方框圖
LM5046方案介紹：
The LM5046 evaluation board is designed to provide the design engineer with a fully functional power converter based on the phase-shifted full-bridge topology to evaluate the LM5046 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 × 1.45 × 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.
LM5046方案原理圖：
圖2. LM5046方案原理圖
LM5046方案材料清單：
PCB元件布局圖：
