原标题：Semtech SC174输出4A降压稳压方案

　　Semtech 公司的SC174是 4A降压稳压器,它采用Semtech先进的专利架构,在点负载(POL)应用时有最好的动态范围.输入电压从3V到5.5V,输出电压从0.75V 到 95% x VIN可编程,输出电流高达4A,峰值效率高达95%,具有短路,过压和欠压以及超温保护,内部有软起动和超级降功耗,主要用在网络设备,嵌入系统,医疗设备,办公自动化,仪表和手提设备,消费类电子和5V POL转换器.本文介绍了SC174主要特性,方框图,多种典型应用电路以及PCB布局图.

　　The SC174 is an integrated, synchronous 4A EcoSpeedTM step-down regulator, which incorporates Semtech’s advanced, patented adaptive on-time architecture to achieve best-in-class performance in dynamic point-of load applications. The input voltage range is 3V to 5.5V with a programmable output voltage from 0.75V up to 95% x VIN. The device features low-RDS(ON) internal switches and optional PSAVE mode for high efficiency across the output load range.

　　Adaptive on-time control provides programmable pseudo- fixed frequency operation and excellent transient performance. The switching frequency can be set from 200kHz to 1MHz - allowing the designer to reduce external LC filtering and minimize light load (standby) losses. Disabling PSAVE operation reduces output voltage ripple at light load for ceramic output capacitors.

　　Additional features include cycle-by-cycle current limit, soft start, input UVLO and output OV protection, and over temperature protection. The open-drain PGOOD pin provides output status. Standby current is less than 10μA when disabled.

　　The device is available in a low profile, thermally enhanced MLPD-3x3mm 10-pin package.

　　SC174主要特性:

　　VIN: 3V to 5.5V

　　VOUT: 0.75V to 95% x VIN

　　IOUT: Up to 4A

　　Low RDS(ON) Switches

　　Up to 95% Peak Efficiency

　　High Output Accuracy

　　Small Ceramic Capacitors

　　Power Good Pin (Open-Drain)

　　Patented Adaptive On-Time Control:

　　Excellent Transient Response

　　Programmable Pseudo-fixed Frequency

　　Fault Protection Features:

　　Cycle-by-Cycle Current Limit

　　Short Circuit Protection

　　Over and Under Output Voltage Protection

　　Over-Temperature

　　Internal Soft start

　　Ultrasonic Power Save

　　Smart Power Save

　　Ultra-Small Lead-Free 3x3mm,10-Pin MLPD Package

　　Fully WEEE and RoHS Compliant

　　SC174应用:

　　Networking Equipment, Embedded Systems

　　Medical Equipment, Office Automation

　　Instrumentation, Portable Systems

　　Consumer Devices (DTV, Set-top Box, ... )

　　5V POL Converters

　　图1.SC174方框图

　　图2.SC174典型应用电路

　　图3.SC174 PCB布局电路图

　　图.SC174 应用电路:1.2V输出/0-4A负载电流(Vin=3V 到5.5V)

　　图.SC174 应用电路:3.3V输出/0-4A负载电流(Vin= 5.0V)