原标题：ADI LTM4691两路开关模式2A DC－DC电源解决方案

　　ADI公司的LTM4691是完整的两路开关模式2A输出的DC/DC电源,包括了开关控制器,功率FET,电感器和所有支持元件.输入电压2.25V到3.6V,有两路输出,可编输出电压从0.5V到3.6V,由外设电阻设定.它的高效率设计每路提供高达2A连续输出电流,仅需要输入和输出电容. LTM4691工作在强制连续模式,用于低噪音脉冲跳跃模式或为了轻负载时高效率而采用突变模式.典型的降压开关频率2MHz,能从1MHz到3MHz同步化.高开关频率和电流模式架构对线路和负载变化有非常快瞬态响应而没有牺牲稳定性.其它特性还包括精密运行阈值,PGOOD信号,输出过压电压,热关断和输出短路保护.输出电压调整率为±1.5%,180反相运行,内部具有软起动和热补偿.主要用在通信,网络和工业设备,点负载调整以及FPGA,ASIC核电源.本文介绍了LTM4691主要特性,框图和多种应用电路,以及演示板DC2910A主要性能指标,测试建立图,电路图,材料清单和PCB装配图.

　　The LTMR4691 is a complete dual 2A output switching mode DC/DC power supply in a tiny 3mm × 4mm × 1.18mm LGA package. Included in the package are the switching controller, power FETs, inductors and all supporting components. Operating over an input voltage range of 2.25V to 3.6V, the LTM4691 supports two outputs with programmable output voltage range from 0.5V to 2.5V set by external resistors. Its high efficiency design

　　delivers up to 2A continuous current on each output. Only bulk input and output capacitors are needed.

　　The LTM4691 operates in forced continuous mode for low noise pulse-skipping mode or Burst Mode operation for high efficiency at lights loads. The typical buck switching frequency is 2MHz and can be synchronized from 1MHz to 3MHz. Its high switching frequency and a current mode architecture enables a very fast transient response to line

　　and load changes without sacrificing stability.

　　Other features include precision run thresholds, a PGOOD signal, output overvoltage protection, thermal shutdown and output short-circuit protection. The LTM4691 is Pb-free and RoHS compliant.

　　LTM4691主要特性:

　　n Tiny Surface Mount, Low Profile 3mmx 4mmx 1.18mm LGA Package

　　n Input Voltage Range: 2.25V to 3.6V

　　n Dual 2A DC Output Current

　　n ±1.5% Total Output Voltage Regulation

　　n Current Mode Control, Fast Transient Response

　　n External Frequency Synchronization

　　n 180 Out-of-Phase Operation

　　n Selectable Pulse-Skipping Mode/Burst ModeR Operation/Forced Continuous Mode

　　n Power Good Indicator

　　n Internal Soft-Start

　　n Internal Compensation

　　n Overvoltage, Overcurrent and Overtemperature Protection

　　LTM4691应用:

　　n Telecom, Networking and Industrial Equipment

　　n Point-of-Load Regulation

　　n FPGA, ASIC Core Supplies

　　图1. LTM4691框图

　　图2. LTM4691应用电路框图:双路1.5V和1.8V 2MHz,2A降压稳压器,Vin=2.5V

　　图3. LTM4691应用电路框图: 双路1.2V和0.8V 2MHz,2A降压稳压器,Vin=3.3V

　　图4. LTM4691应用电路框图: 双路1.2V和0.8V 1MHz,2A降压稳压器,Vin=3.3V

　　图5. LTM4691应用电路框图: 双路1.2V和0.8V 3MHz,2A降压稳压器,Vin=3.3V

　　演示板DC2910A

　　Demonstration circuit 2910A is low VIN, high efficiency, and dual 2A output μModule DC/DC converter. The board operates by default at a fixed 2MHz and can be synchronized from 1MHz to 3MHz via the MODE/SYNC pin. With its high switching frequency and current mode architecture, a fast transient response to line and load changes is possible without sacrificing stability. The DC2910A can be used in forced continuous mode or pulse skip mode for low noise, or in burst mode operation forhigh efficiency at light loads. The demo board features the LTM?4691, which is available in a low profile 3mm x 4mm x 1.2mm LGA package. Please see the LTM4691 datasheet for more detailed information.

　　It is recommended to read the data sheet for the LTM4691 prior to making any changes to the DC2910A.

　　演示板DC2910A主要性能指标:

　　图6. 演示板DC2910A外形图

　　图7. 演示板DC2910A测试建立图

　　图8. 演示板DC2910A电路图