同步降压稳压器解决方案

Keywords：Constant On-Time ，capacitor network， EquivalentSeriesResistance
基本特性：
LM3103同步降压开关稳压器适用于4.5V至42V的输入电压，而且开关频率可以自行设定，最高可达1MHz。LM3102芯片可为负载提供高达2.5A的电流，而输出电压则低至0.8V。LM3103芯片可以提供高达750mA的电流，而输出电压则低至0.6V。两款稳压器都可为线路及负载提供卓越的稳压效果。若负载较低，LM3102及LM3103都可采用间断模式操作，以便提高效率。在启动时，它们都不会对预偏置的输出电容器放电，因而可确保一电压斜坡的稳定性。此外，这两款芯片还具有可编程软启动、谷值电流限幅、输出过压保护以及过热停机保护等多项特色功能。
方案特点：
The LM3103 Step Down Switching Regulator features all required functions to implement a cost effective,efficient buck power converter capable of supplying 0.75A to loads. The Constant On-Time (COT)egulation scheme requires no loop compensation, results in a fast load transient response and simple circuit implementation which allows a low component count, and consequently very small overall board space is required for a typical application. The regulator can function properly even with an all ceramic output capacitor network, and does not rely on the output capacitor’s ESR for stability. The operating frequency remains constant with line variations due to the inverse relationship between the input voltage and the on-time. Protection features include output over-voltage protection, thermal shutdown, VCC undervoltage lock-out, gate drive under-voltage lock-out. The LM3103 is available in the thermally enhanced  HTSSOP-16 package。
Demonstration Board Schematic and PCB




Design Procedure
The LM3103 is easy to use compared with other devices available on the market because it integrates all key components, including both the main and synchronous power MOSFETs, in a single package and requires no loop compensation owing to the use of the Constant On-Time (COT) hysteretic control scheme.
The design of the demonstration board in this application note is...