Linear LTC3569中功率降压DC电源转换方案

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Linear LTC3569中功率降压DC电源转换方案

作者：时间：2009-10-29 09:12 来源：

Linear公司的LTC3569包含三个同步降压DC/DC转换器,适合中功率应用.输入电压从2.5V到5.5V,工作频率从1MHz到3MHz,三个输出电压是相互独立的:一个输入1.2A,两个输出600mA,静态电流低于100μA. LTC3569可用于需要多个电源的手提设备,通用降压DC/DC转换器以及动态电压缩放应用.本文介绍了LTC3569的主要特性,方框图以及典型应用, 双路降压DC/DC稳压器和双路可编程降压D/DC稳压器电路图.

The LTC3569 contains three monolithic, synchronous step-down DC/DC converters. Intended for medium power applications, it operates over a 2.5V to 5.5V input voltage
range. The operating frequency is adjustable from 1MHz to 3MHz, allowing the use of tiny, low cost capacitors and inductors. The three output voltages are independently
programmable by toggling the EN pins up to 15 times, lowering the 800mV FB references by 25mV per cycle. The first buck regulator sources load currents up to 1200mA.

The other two buck regulators each provide 600mA. The two 600mA buck regulators can also be configured to operate as slave power stages, running in parallel with another internal buck regulator to supply higher load currents. When operating as parallel, slave output stages, discrete external components are shared and available output currents sum together.

LTC3569主要特性:

Three Independent Current Mode Buck DC/DC Regulators (1.2A and 2x 600mA)
Single Pin Programmable VFB Servo Voltages from 800mV Down to 425mV (in 25mV Steps)
n Pull VFB High to Make Each 600mA Buck a Slave for Higher Current Operation
Pulse Skip or Burst Mode Operation
Programmable Switching Frequency (1MHz to 3MHz) or Fixed 2.25MHz
Synchronizable (1.2MHz to 3MHz)
VIN Range 2.5V to 5.5V
All Regulators Internally Compensated
PGOOD Output Flag
Quiescent Current <100μA (All Regulators in Burst Mode Operation)
Zero Shutdown Current
Overtemperature and Short-Circuit Protection
Tiny 3mm × 3mm 20-Lead QFN and Thermally Enhanced TSSOP FE-16 Packages

LTC3569应用:
Portable Applications with Multiple Supply Rails
General Purpose Step-Down DC/DC
Dynamic Voltage Scaling Applications