NS LMZ14203H输入42V输出3A电源的实现

 

　　LMZ14203H电源模块适用于6V至42V的输入电压轨，并可提供可调的高输出电压，其电压值可达24V.工程师只需使用一个电阻便可调整开关频率，这令电路设计具有更大的灵活性。这款电源模块除了可与同系列的其他型号引脚兼容外，还集成了隔离电感器，令其效率可高达97%.集成的电感器可以减轻电磁干扰（EMI），令这几款电源模块符合 CISPR 22 B 类电磁波辐射及传导发射等标准的规定。LMZ14203H电源模块可驱动1A至3A的负载，适用于采用分立式负载点架构（POL）的供电系统，并可在系统中生成中间总线电压。超高效率与出众的热性能令这三款电源模块理想用于无法通风散热的系统。此外，这几款产品与特殊应用电路搭配使用时，可生成-15V 的偏压供电，令音频放大器（例如美国国家半导体的LME49880芯片）可以获得更宽的动态范围。

　　LMZ14203H: 3A SIMPLE SWITCHER? Power Module with 42V Maximum Input

　　The LMZ14203H SIMPLE SWITCHER power module is an easy-to-use step-down DC-DC solution capable of driving up to 3A load with exceptional power conversion efficiency, line and load regulation, and output accuracy. The LMZ14203H is available in an innovative package that enhances thermal performance and allows for hand or machine soldering.

　　The LMZ14203H can accept an input voltage rail between 6V and 42V and deliver an adjustable and highly accurate output voltage as low as 5V. The LMZ14203H only requires three external resistors and four external capacitors to complete the power solution. The LMZ14203H is a reliable and robust design with the following protection features: thermal shutdown, input under-voltage lockout, output over-voltage protection, short-circuit protection, output current limit, and allows startup into a pre-biased output. A single resistor adjusts the switching frequency up to 1 MHz.

　　LMZ14203H电指标：

　　■ Up to 3A output current

　　■ Input voltage range 6V to 42V

　　■ Output voltage as low as 5V

　　■ Efficiency up to 97%

　　LMZ14203H主要特性：

　　■ Integrated shielded inductor

　　■ Simple PCB layout

　　■ Flexible startup sequencing using external soft-start and precision enable

　　■ Protection against inrush currents

　　■ Input UVLO and output short circuit protection

　　■ –40℃ to 125℃ junction temperature range

　　■ Single exposed pad and standard pinout for easy mounting and manufacturing

　　■ Low output voltage ripple

　　■ Pin-to-pin compatible family:

　　LMZ14203H/2H/1H （42V max 3A, 2A, 1A）

　　LMZ14203/2/1 （42V max 3A, 2A, 1A）

　　LMZ12003/2/1 （20V max 3A, 2A, 1A）

　　Fully enabled for Webench Power Designer

　　LMZ14203H主要优势：

　　■ High efficiency reduces system heat generation

　　■ Low radiated EMI （EN 55022 Class B compliant）

　　■ No compensation required

　　■ Low package thermal resistance

　　LMZ14203H应用：

　　■ Intermediate bus conversions to 12V and 24V rail

　　■ Time critical projects

　　■ Space constrained / high thermal requirement applications

　　■ Negative output voltage applications

图1.LMZ14203H应用方框图

图2.LMZ14203H连接框图Connection Diagram

　　LMZ14203H/02H/01H评估板

　　LMZ14203H/02H/01H Evaluation Board

　　The LMZ14203H/02H/01H SIMPLE SWITCHER power modules for high output voltage are easy-to-use DC-DC solutions capable of driving up to a 3A load with exceptional power conversion efficiency, output voltage accuracy, line and load regulation. They are available in an innovative package that enhances thermal performance and allows for hand or machine soldering.

　　The LMZ14203H/02H/01H Evaluation Board is configured for 12V output voltage from 15V to 42V input. The precision enable input allows for programmable UVLO of the input supply.

　　The resistor voltage pider RENT and RENB set the input UVLO threshold. Connect the VIN turret terminal to the EN turret on the board to enable operation.

　　The external soft-start capacitor CSS facilitates controlled startup output rise time. The resistors RFBT and RFBB set the output voltage. An output feed-forward capacitor CFF across the upper feedback resistor trims for optimum transient response.

　　The control loop operates well with low ESR output capacitors such as ceramic and polymer electrolytic capacitors.

　　The resistor RON sets the operating frequency.The LMZ14203H/02H/01H PCB layout offers excellent thermal performance, achieving junction-to-ambient thermal resistance θJA of 14.9℃/W. The evaluation board with its default Bill of Materials offers great EMI performance, complying with the EN 55022 Class B radiated emissions standard.

　　The solution also complies with the CISPR22 conducted emissions standard with the addition of a small input filter

　　LMZ14203H/02H/01H评估板指标：

　　VIN = 15V to 42V

　　VOUT = 12V

　　3A max load at 24VIN and 65℃ TAMB

　　Low radiated EMI （EN 55022 Class B compliant）

　　400kHz switching frequency

　　Enable UVLO set at 13.5V

　　θJA = 14.9℃/W

　　4 copper layers

　　2 oz copper on top and bottom layer

　　1 oz copper on internal layers

　　6.985 cm x 7.620 cm （2.75 in x 3 in） with 1.575 cm （。062 in） thickness of FR4 laminate material

图3.LMZ14203H/02H/01H评估板电路图
LMZ1420xH评估板材料清单: VIN = 15V to 42V, VOUT = 12V, IOUT (MAX) = 3A/2A/1A


图4.LMZ14203H/02H/01H评估板详细电路图:DNS=元件没安装

图5.EMI LC滤波器连接图