基于LTC3615設計的雙路3A同步穩壓技術

Linear公司的LTC3615是雙路3A同步降壓穩壓器,采用電流模式固定頻率架構.輸入電壓2.25V-5.5V,輸出電流2x3A,效率高達94%,輸出電壓低至0.6V,輸出電壓精度±1%,可調整開關頻率高達4MHz,主要用作點負載電源,分布式電源,手提計算機電源,DDR存儲器電源和手持設備.本文介紹了LTC3615主要特性, 方框圖以及多種典型應用電路.

The LTC?3615 is a dual 3A synchronous step-down regula-tor using a current mode, constant-frequency architecture. The DC supply current is only 130μA (Burst Mode operation at no-load) while maintaining the output voltages, drop-ping to zero current in shutdown. The 2.25V to 5.5V input supply range makes the LTC3615 ideally suited for single Li-Ion applications. 100% duty cycle capability provides low dropout operation, which extends operating time in battery-operated systems.

The operating frequency is externally programmable up to 4MHz, allowing the use of small surface mount inductors. 0°, 90°, or 180° of phase shift between the two channels can be selected to minimize input current ripple and output voltage ripple in a single 6A output configuration. Programmable slew rate limiting reduces EMI, and external synchronization can be applied up to 4MHz.

The internal synchronous switches increase efficiency and eliminate the need for external catch diodes, saving external components and board space.

The LTC3615 is offered in leadless 24-pin 4mm × 4mm QFN and thermally enhanced 24-pin TSSOP packages.

LTC3615主要特性:

High Efficiency: Up to 94%

Dual Outputs with 2 × 3A Output Current Capability

Low Output Ripple Burst Mode? Operation: IQ = 130μA

2.25V to 5.5V Input Voltage Range

±1% Output Voltage Accuracy

Output Voltages Down to 0.6V

Programmable Slew Rate at Switch Pins

Low Dropout Operation: 100% Duty Cycle

Shutdown Current ≤1μA

Adjustable Switching Frequency Up to 4MHz

Internal or External Compensation

Selectable Pulse-Skipping/Forced Continuous/Burst Mode Operation with Adjustable Burst Clamp

Optional Active Voltage Positioning (AVP) with Internal Compensation

Selectable 0°/90°/180° Phase Shift Between Channels

Fixed Internal and Programmable External Soft-Start

Accurate Start-Up Tracking Capability

DDR Memory Mode IOUT = ±1.5A

Available in 4mm × 4mm QFN-24 and TSSOP-24 Packages

LTC3615應用:

Point-of-Load Supplies

Distributed Power Supplies

Portable Computer Systems

DDR Memory Termination

Handheld Devices

圖1.LTC3615方框圖

圖2.LTC3615典型應用電路

圖3.LTC3615應用電路:通路1軟起動和補償由外部編程, 通路軟起動和補償由內部編程

圖4.LTC3615外部補償應用電路

圖5.LTC3615 DDR存儲器應用電路

圖6.LTC3615主從應用電路