Linear LT3509雙路36V降壓開關穩壓器應用方案

?Linear 公司的LT3509是雙路3.6V-36V電流模式降壓開關穩壓器,每路的內部開關能提供700mA的輸出電流,集成了過壓關閉和逐個周期的電流限制以及熱關斷等保護措施.最大占空比達95%,開關頻率從300kHz到2.2MHz可調整,可采用小型電感和陶瓷電容. LT3509主要應用在汽車電子,工業控制,網絡設備和CPU,DSP或FPGA的電源.本文介紹了LT3509的主要特性,功能方框圖以及三種典型應用電路.

The LT3509 is a dual, current mode, step-down switching regulator, with internal power switches each capable of providing 700mA output current. This regulator provides a compact and robust solution for multi-rail systems in harsh environments. It incorporates several protection features including overvoltage lockout and cycle-by-cycle current limit. Thermal shutdown provides additional protection.

The loop compensation components and the boost diodes are integrated on-chip. Switching frequency is set by a single external resistor. External synchronization is also
possible. The high maximum switching frequency allows the use of small inductors and ceramic capacitors for low ripple. Constant frequency operation above the AM band avoids interference with radio reception, making the LT3509 well suited for automotive applications. Each regulator has an independent shutdown and soft-start control pin.

When both converters are powered down, the common circuitry enters a low current shutdown state.

LT3509主要特性:

Two 700mA Switching Regulators with Internal Power Switches

Wide 3.6V to 36V Operating Range

Overvoltage Lockout Protects Circuit Through 60V Supply Transients

Short-Circuit Robust

Low Dropout Voltage—95% Maximum Duty Cycle

Adjustable 300kHz to 2.2MHz Switching Frequency Synchronizable Over the Full Range

Uses Small Inductors and Ceramic Capacitors

Integrated Boost Diodes

Internal Compensation

Thermally Enhanced 14-Lead (4mmx3mm) DFN and 16 Lead MSOP Packages

LT3509應用:

Automotive Electronics

Industrial Controls

Wall Transformer Regulation

Networking Devices

CPU, DSP, or FPGA Power
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圖1.LT3509功能方框圖

圖2.LT3509應用電路(1):3.3V和5V雙輸出降壓轉換器

圖3.LT3509應用電路(2):1.8V和3.3V輸出,同步于300kHz-600kHz