Linear LT3570升降压电源转换方案

Linear 公司的LT3570是升/降压电源转换器,内部集成了功率开关和LDO控制器,转换器的限流是1.5A,输入电压从2.5V到36V,开关频率高达2MHz,并通过外接电阻进行编程,振荡器能和高达2.75MHz外部时钟同步. LT3570可广泛应用在有线和卫星电视机顶盒,汽车系统,通信系统以及TFT LCD显示器.本文介绍了LT3570主要特性,方框图,应用电路以及
LT3570用在”Dying Gasp”系统和DSL调制解调器的电路图.

The LT3570 is a buck and boost converter with internal power switches and LDO controller. Each converter is designed with a 1.5A current limit and an input range from 2.5V to 36V, making the LT3570 ideal for a wide variety of applications. Switching frequencies up to 2MHz are programmed with an external timing resistor and the oscillator can be synchronized to an external clock up to 2.75MHz.

The LT3570 features a programmable soft-start function that limits the feedback voltage during start-up helping prevent overshoot and limiting inrush current. The LDO controller is capable of delivering up to 10mA of base current to an external NPN transistor.

主要特性:
2.5V to 36V Input Voltage Range
Programmable Switching Frequency
from 500kHz to 2MHz
Synchronizable Up to 2.75MHz
VOUT(MIN): 0.8V
Independent Soft-Start for Each Converter
Separate VIN Supplies for Each Converter
Duty Cycle Range: 0% to 90% at 1MHz
Available in 24-Lead (4mm 4mm) QFN and
20-Lead TSSOP Packages
应用:
Cable and Satellite Set-Top Boxes
Automotive Systems
Telecom Systems
“Dying Gasp” Systems
TFT LCD Displays



图1.LT3570典型应用



图2.LT3570方框图



图3.LT3570用在DSL调制解调器的电路图



图.LT3570用在”Dying Gasp”系统的电路图