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电源和散热管理

应用笔记

了解电容特性,为应用选择最佳器件

AN-1099:ADI公司LDO的电容选型指南

像其它电子元器件一样,电容也不是完美无缺的。电容有寄生电阻和电感,而且容值会随着温度和偏置电压而变化。为许多旁路应用或电容实际容值非常重要的应用选择电容时,必须考虑这些因素。电容选择不当可能会导致电路不稳定,噪声或功耗过大,产品寿命缩短,以及电路行为不可预测等现象。这篇3页的应用笔记旨在帮助设计人员为应用选择最佳器件。

可编程时序控制器控制线路卡和刀片卡的上电

AN-1086:ADM106x的热插拔应用

超级时序控制器系列ADM106x super sequencers®能够精确监控多个输入轨,ADM1062至ADM1067有10个专用输入引脚,ADM1068和ADM1069有8个专用输入引脚。各引脚具有两个内部可编程比较器电路。可以将这些电路编程为仅欠压、仅过压或欠压/过压模式,从而针对各个受监控的电源设置跳变点。ADM106x内置一个电源仲裁器,它能自动从其输入电源引脚上的最高电压轨为器件供电。这些器件通常用于电信基础设施(中央交换局和基站)线路卡和服务器刀片卡等需要热插拔到带电背板的应用。在线路卡应用中,ADM106x可能需要是电路板上第一个上电的器件,因为它必须监控电路板上的输入电源;如果电源在设定限值以内,则向热插拔控制器提供一个使能信号,从而允许电路板的主要部分上电。这篇2页的应用笔记描述卡片在带电背板中热插拔的情况下,ADM106x的输入电源接通时必须考虑的设计要求。

利用反相降压/升压拓扑结构从正电源产生负电压

AN-1083:利用开关调节器ADP2300和ADP2301设计反相降压/升压转换器

DC/DC转换器设计人员需要使用多功能开关控制器和调节器来解决电源管理挑战。ADP2300/ADP2301开关调节器可提供从20 V输入电压到0.8 V输出电压的异步降压功能,输出电流可高达1.2 A,开关频率分别为700 kHz和1.4 MHz。降压拓扑结构的实现在ADP2300/ADP2301数据手册中已有详细说明,并受Buck Designer工具(ADIsimPower DC/DC调节器设计工具的扩展版本)的支持。虽然ADP230x系列是针对降压应用而设计,但它也能在不增加成本、器件数量和尺寸的前提下,实现反相降压/升压拓扑结构。这篇8页的应用笔记讨论如何利用ADP230x实现异步反相降压/升压拓扑结构,以便从正电源产生负电压。

利用两个简单时序控制器控制两个电源的开启和关闭

AN-1080:利用简单时序控制器ADM108x进行上电和关断时序控制

ADM108x简单时序控制器可在上电期间对两个电压轨进行简单的时序控制,时间延迟可通过电容进行编程。利用该系列的两个器件可构成一个简单的电路,从而以各自可编程的时间延迟对两个电压轨的上电和关断进行时序控制。这篇8页的应用笔记说明如何设计这种电路。

使用ADP1870/ADP1872的高效率升压/降压DC-DC转换器

AN-1075:使用ADP1870/ADP1872的同步反向SEPIC为同相降压/升压应用提供高效率

许多市场对高效同相DC-DC转换器的要求越来越高,不但能在降压或升压模式下工作,还可将输入电压减小或增大至所需的调节电压,并且具有极低的成本和功率损耗、元件数量最少。反向单端初级电感转换器(SEPIC)也称为Zeta转换器,具有许多非常适合此项功能的特性。这篇12页的应用笔记分析采用ADP1870/ADP1872同步开关控制器的操作和实施方案,说明适合此应用的一些特性。

完整的电源开发套件包

Power Management RedyKit

传统评估板提供单电压输出,只能由制造商进行高精度调整,或者在可调型号内通过两个精密电阻进行设置。如果用户需要不同的输出电压,必须订购不同的IC。为了简化这一过程,ADI公司提供一款完整的产品评估套件RedyKit,其中包括两种评估板,外加产品系列的所有标准选项,用户可订购这款套件来评估所有选项。各IC按型号分类存放,抗静电拉链袋上清楚地印着ADI产品型号。

使用LDO降低噪声,解决EMI和PCB布线引起的调节问题,并提高效率

AN-1072:如何成功地应用低压差调节器

低压差(LDO)调节器能够在较宽的负载电流和输入电压范围内保持额定输出电压,输入与输出电压之间的差异极小。这篇8页的应用笔记探讨LDO基本拓扑结构,说明重要的技术规格,并展示低压差调节器在系统中的应用。同时给出采用ADI公司LDO系列设计特色的示例。有关LDO的更多信息,请访问 www.analog.com/linear-regulators.

Circuits from the Lab

新产品简介

June 2011

Super Sequencer with margining control and nonvolatile fault recording

adm1169The ADM1169 super sequencer® configurable power-supply supervisor monitors and sequences up to eight supplies in multiple-supply systems. Eight programmable inputs can be used for monitoring overvoltage, undervoltage, or out-of-window faults: one can be used for a supply voltage up to 14.4 V; three can be used for supply voltages up to 6 V; and four can be used for supply voltages between 0.573 V and 1.375 V—or digital signals, such as reset, power good, or fault. Eight programmable outputs can enable supplies individually under the control of the sequencing engine. Six of these outputs can provide a 12-V gate drive to N‑channel FETs. The sequencing engine provides up to 63 states, enabling flexible sequencing of the outputs based upon the condition of the inputs. Nonvolatile EEPROM can store user-defined data or, when controlled by the sequencing engine, it can automatically log supply faults or system input faults. A 12-bit ADC measures supervised voltages and on-chip or remote temperatures, and four 8-bit DACs implement closed-loop power-supply margining. For improved redundancy, the device is powered from the highest of the four voltages on the voltage-monitor inputs. Operating with a 3-V to 14.4-V supply; the ADM1169 draws 4.2 mA. Available in 32‑lead LQFP and 40-lead LFCSP packages, it is specified from –40°C to +85°C and priced at $6.49 in 1000s.

Hot-Swap Controller and Digital Power/Energy Monitor

adm1276The ADM1276 hot-swap controller allows circuit boards to be inserted into or removed from a live backplane without damage. The on-chip 12-bit ADC monitors the supply voltage, load current, and output voltage with ±0.7% accuracy, and communicates the results via a PMBus interface. The load current is detected with an on-chip current-sense amplifier, which measures the voltage across a sense resistor in the power path. The device controls supply voltages in the 2-V to 20-V range by modulating the gate voltage on an external N-channel FET pass device. The current limit is set by limiting the voltage across the sense resistor to a programmable value between 5 mV and 25 mV. Overvoltage and undervoltage protection thresholds are programmed with external resistors; a power-good signal indicates valid output voltage. Available in a 20-lead LFCSP package, it is specified from –40°C to +85°C and priced from $5.29 in 1000s.

Dual-output Low-Dropout Regulator drives 300-mA loads

adp223The ADP223 dual adjustable-output low-dropout regulator (LDO) can be configured to provide output voltages between 0.5 V and 5 V by adding two resistors per channel. It features ±1% accuracy, 76-dB power-supply rejection, 27-µV rms noise, 300‑mA drive capability, and 120-mV dropout voltage, making it ideal for battery-powered applications with demanding requirements for performance and board area. Two active-high inputs independently enable the two outputs, which can be connected in parallel for increased output current. The device offers overcurrent and thermal protection. Operating with a 2.5-V to 5.5-V supply, the ADP223 consumes 180 µA with a 300-mA load, 65 µA with no load, and 0.1 µA in shutdown mode. Available in an 8-lead, 2-mm × 2-mm LFCSP package, it is specified from –40°C to +125°C and priced at $0.49 in 1000s.

Micro-PMU includes 800-mA buck regulator, 300-mA LDO, supervisory functions

adp5043The ADP5043micro-power-management unit (µPMU) combines a high-performance 1.5-V, 800-mA buck regulator and a 3.3-V, 300-mA low-dropout regulator (LDO). A supervisory circuit monitors voltage levels and code execution using a watchdog timer—and provides reset signals—increasing system reliability in microprocessor-based systems. If not asserted within the specified time period, a second watchdog timer power cycles the µPMU output voltages to provide a full hardware reset. The buck converter can operate in forced pulse-width modulation (PWM) mode for lowest ripple, or can automatically switch between PWM mode and power-save mode to maximize efficiency at light loads. The LDO specifies 4-mV dropout with a 10-mA load, and 60-mV dropout with a 200-mA load. The buck regulator’s 2.3-V to 5.5-V input range allows the use of standard power sources, including lithium-, alkaline-, and NiMH cells and batteries. The LDO operates from a 1.7-V to 5.5-V input voltage. Available in a 20-lead, LFCSP package, the ADP5043 is specified from –40°C to +125°C and priced at $1.79 in 1000s.

9-channel LED Driver includes charge pump, automated lighting effects

adp8866The ADP8866LED driver combines programmable backlight LED driving with automatic blinking functions. Nine LED drivers are independently programmable at currents up to 25 mA. Once programmed, the current level, fade time, and blinking rate are executed autonomously on a loop. Separate fade-in and fade-out times can be set for the backlight LEDs. A two-capacitor charge pump, which can provide up to 240 mA, powers the drivers. The robust design includes soft start and protection against short circuits, overvoltage, and over-temperature. Operating with a single 2.5-V to 5.5-V supply, the ADP8866 draws 1.2 mA in switching mode and 0.25 μA in standby mode. Available in a 20-lead LFCSP package, it is specified from –40°C to +105°C and priced at $1.48 in 1000s.

2011年5月

超级时序控制器监控8个电源,具有非易失性故障记录功能

adm1168 ADM1168 Super Sequencer®可配置电源监控器可以对多电源系统中的多达8个电源进行监控和时序控制。8路可编程输入可用来监控过压、欠压或超出窗口故障:一路用来监控高达14.4 V的电源电压,三路用来监控高达6 V的电源电压,四路用来监控0.573 V至1.375 V的电源电压或者复位、电源良好、故障等数字信号。8路可编程输出可以在时序控制引擎的控制下分别使能各电源,其中六路输出可以向N沟道FET提供12 V栅极驱动。时序控制引擎提供多达63种状态,可以根据输入状况对输出进行灵活的时序控制。非易失性EEPROM可以存储用户自定义的数据,或者在时序控制引擎的控制下,它可以自动记录电源故障或系统输入故障。为提高冗余性,该器件采用电压监控输入端四个电压中的最高电压供电。ADM1168采用3 V至14.4 V电源供电,功耗为4.2 mA。它采用32引脚LQFP封装,额定温度范围为–40°C至+85°C,千片订量报价为5.49美元/片。

采用逻辑电平控制的高端电源开关

adp197 ADP197是一款高端电源开关,可将闲置负载的电源断开,以延长移动电话、数码相机和音频器件的电池使用时间。通过12 mΩ导通电阻,N沟道MOSFET开关元件可最大程度地减少功率损耗,同时可处理高达3 A的连续电流。片内电平转换器确保与现代处理器和控制器逻辑兼容。ADP197采用1.8 V至5.5 V单电源供电,使能时耗用的地电流为18 μA,关断时为100 nA。它采用紧凑的6引脚1 mm x 1.5 mm WLCSP封装,额定温度范围为–40°C至+85°C,千片订量报价为0.46美元/片。

同步降压控制器利用PWM实现快速瞬变响应,并利用谷值电流模式提高噪声灵敏度

adp1874/adp1875 ADP1874ADP1875均为电流模式同步降压型控制器,采用恒定导通时间、伪固定频率电流控制方案,具备出色的瞬态响应、最佳稳定性和限流保护特性;谷值电流控制模式能够在低占空比时提供最佳性能。这些器件设计用来驱动N沟道功率级,可以调节低至0.6 V的输出电压。ADP1875还提供一种省电模式(PSM),能够利用脉冲跳跃维持输出调节,同时提高轻负载时的系统效率。这些器件提供三种频率选项:300 kHz、600 kHz和1.0 MHz,此外还有PSM选项。低压偏置通过内置的5 V低压差调节器(LDO)提供。可编程软启动功能在启动期间能够限制输入电源的浪涌电流,在预充电输出状况下能够提供反向电流保护。ADP184/75采用2.95 V至20 V输入电压,静态功耗为1.1 mA,关断模式下为140 µA。额定温度范围为–40°C至+125°C,采用16引脚QSOP封装,千片订量报价为1.32美元/片。

2011年4月

I/O扩展器和键盘控制器

adp5589 ADP5589I/O端口扩展器和键盘矩阵控制器针对需要大键盘矩阵和/或扩展I/O线的便携式和非便携式设备而设计。它能处理所有按键扫描和解码,使主处理器不必监控键盘,从而降低功耗并提高其它功能的可用带宽。当有新的按键事件发生或者通用输入发生变化时,它通过一条中断线通知主处理器。片内FIFO最多可以存储16个事件,通过I2C兼容型接口可以读取这些事件。它还具有可编程逻辑功能和可编程PWM发生器,支持将其它常见功能集成到电路板设计。ADP5589采用24引脚LFCSP封装,千片订量报价为1.20美元/片。

技术文章

Marcus O'Sullivan, High Power Systems, Power Systems Design, 5/8/2011

Ken Marasco, LDOs solve portable power management challenges, Project Power, 4/1/2011

James Xie, Jerry Zhai, and Jason Duan, Digitales Power-Management hilft in Schaltnetzteilen die Effizienz auch bei geringer Last zu erh鰄en, Elektronik Praxis, 3/3/2011

Jon Kraft, 如何在激活手机LED指示灯的同时保持待机时间不受影响, Analog Dialogue, 3/1/2011

Ken Marasco, 低噪声LDO增强对噪声敏感的模拟和RF电路, EDN Europe, 2/1/2011

Colm Slattery, 工业控制中的电源性能, EPD, 2/1/2011

Glenn Morita, 低压差调节器——为什么旁路电容的选择很重要, Analog Dialogue, 1/11/2011

Petre Minciunescu, 智能电网计量及合适的架构, Electronic Products, 12/21/2011

Michael Cobb, 高速ADC供电指南, EE Times Europe, 12/13/2010

James Frame, Jeritt Kent and Ian Lawee, 智能电网通信的发展:持续改进智能电网, Microwave Journal, 12/1/2010

在线研讨会和教程

利用高效率集成开关调节器解决电源设计问题 -- 本研讨会探讨电源设计人员在多轨系统级设计中面临的典型挑战。了解错相工作的频率同步如何能降低EMI干扰,避免系统性能受影响或下降。

现场可编程门阵列(FPGA)的供电——了解基础知识 -- 本研讨会讨论现场可编程门阵列(FPGA)的特殊电源要求,以及用来确保无故障工作的合适电源产品。其中特别介绍一种针对高性能FPGA的供电要求而优化的多功能DC-DC调节器。

在高速模数转换器应用中采用开关调节器进行设计 -- 在高速模数转换器应用中,利用开关电源提高系统效率且不会降低性能。

 

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