5V／10W DC—DC变换器

用3端DC－DCPWM开关TOP414G构成的SV10W隔离的DC－DC变换器示于图1。此变换器具有宽输入范围（36～72VDC输入）,输出5V2．0A。图1中的TOP414G是PowerIntegrations公司一款3端DC－DCPWM开关,它具有DC－DC变换器所需的所有功能。它含有：带控制导通栅极驱动器的高压N沟道功率MOSFET,带集成120kHz振荡器的电压模式PWM控制器,高电压启动偏置电路,带隙分支基准,环路补偿的偏置并联调节器／误差放大器和失效保护电路（见图2）。在图1的变换器电路中最大元件高度是12mm。EFD－20变压器铁芯的选择适合这个最大元件高度…     

基于LTC3789的DC/DC变换器设计

为将宽输入范围直流电压变换成稳定直流电压输出,以控制器LTC3789为核心,高速、高频、低损耗MOSFET器件为控制开关,采用恒定频率的电流控制模式,设计了一款能够实现宽范围输入电压同步、无缝、高效的升压-降压DC/DC变换电路,并进行了物理实验验证。实验结果表明,所设计的以LTC3789为控制核心的电路能够实现6-30V直流输入,12.8V稳定直流输出的DC/DC变换,并且电路工作稳定、可靠。     

一种混合集成DC/DC电源调制器的设计

介绍了一种混合集成DC/DC电源调制器的设计,并给出了实验结果。该电路包含延时电路、逻辑运算电路、驱动电路和输出电路,其主要功能是对输入的TTL控制信号进行逻辑运算和延时处理;通过驱动电路后,对 3.3 V、 5 V、 6 V、 12 V电源进行调制,可实现按规定时序为系统供电。     

高效率降压式DC/DC变换器VT103

<正> VT103是VOLTERRA公司推出的一种高效率、低电压输出的降压式DC/DC变换器。该器件主要特点有:输出电压可设定,在输出1.8V时转换效率保证大于90％,输出电压降到1.23V时转换效率仍可保证大于88％;输入电压为2.7～6V;输出电压范围为1.23～5.9V(压差约100mV);最大输出电流为1.2A:内部振荡器频率为1MHz,也可用外部时钟,以减少噪声干扰:有PWM或PFM模式选择,以保证不同负载时都有高的效率;采用PFM模式时,工作电流典型值为125μA;有关闭控制端,在关闭模式时耗电仅为5.5μA(典型值);在低压差     

一种DC/DC斜坡补偿电路的设计

本文提出了一种峰值电流模式控制的DC/DC转换器中斜率补偿电路.电路采用上斜坡补偿（补偿信号与采样信号叠加）方式.电路由采样电路、斜坡信号产生电路、叠加电路共同组成.采样电路采样电感电流信号,并生成一个带有采样信号信息的电流信号,输入到叠加电路,与斜坡信号产生电路生成的一个斜坡电流信号进行叠加,然后共同作于一个电阻之上,输出一个带有采样信号信息与斜坡补偿信息的电压信号,实现斜坡补偿.该信号与误差放大器的输出信号共同输入到PWM（脉冲宽度调制）比较器,两信号经比较后输出驱动信号,控制功率管的关断.     

利用推挽DC／DC转换器固有特性的倍压器

本设计实例能以最少的元件数实现利用单变压器推挽DC/DC转换器的固有倍压特性的宽范围倍压器.它采用高压达林顿晶体管阵列驱动器ULN2023A来实施.该电路具有5V～30V的较宽输入电压范围,并能以适宜的效率提供了1W～4W的典型电源输出.     

DC／DC转换器

12-S24.850DIN DC/DC转换器封装于小型DIN外壳之中,备有一体化DIN安装脚。它可将9-18V输入电压转换为24V输出。 参数包括1％的线路和负载稳定度、750μs的负载瞬变恢复时间和±3％的输出设定点电压精度,该转换器具有短路保护和自动重启功能。(71.50美元,有库存。) Calex Mfg. 传真:00l-925-687-3333 sales@calex.com 查询号:312 PKV3000和PKV5000系列DC/DC转换器具有工业标准的20×32mm底部面积,不到11mm高。有4 个单组输出和3个双组输出型号,电压为3.3、5、12和15V。 输出电压为9-36V(PKV3000)和18-72V(PKV5000)。线路和负载稳定度为±     

DC／DC转换器

高功率转换器不需散热片 Power Qor Tera系列DC/DC转换器在2.5V或2.5V以下输出60A,或在3.3V输出50A。效率从83％到90％(根据输出的不同),而且不需额外的散热片或底盘。 输入电压是48V。特点有:开/关控制,远程感测,     

微功耗PFM升压DC—DC变换器

<正> NCP1402系列器件是微功耗升压DC-DC变换器,它专门为使用1～2节电池的便携式设备提供1.8～5.0V的电源。启动电压力0.8V,工作时可降至0.3V,当输入为2.0V,输出为3.0V时,输出电流可为200mA。在芯片内部含有PFM(脉冲频率调制振荡器)、PFM控制器、PFM比较器、软启动电路、基准电压电路、驱动器等,其内部框图如图1所示。     

轻松选择DC/DC变换器

分布式供电体制(distributed-power architectures,DPA)的盛行,极大地促进了集成DC/DC变换器的发展。本文主要讲述了DC/DC变换器在评测、对比和选型时的需要注意的问题,以协助DPA设计人员在市场上挑选出合适的产品。功率、输入和输出首先要考虑的是输入电压、额定功率以及输出电压的大小和种类。根据额定功率的大小,DC/DC变换器通常可分为超低功率(1W以下)、小功率(1～9W)、中功率(10～150W)和大功率(150W以上)等类别。大多数变换器的输入电压是12V或24V,对于那些要求输入电压可变或者输入电压不标准的场合,可以选用具有宽电源输…     

A current-tripler dc/dc converter

This paper proposes a novel zero-voltage-switching (ZVS) current-tripler dc/dc converter. Compared to the conventional phase-shifted ZVS full-bridge dc/dc converter with current-doubler rectifier, the proposed current-tripler dc/dc converter reduces the synchronous rectifier (SR) conduction loss as well as the transformer winding loss. Furthermore, the proposed transformer structure is very compact, and thus the power density of the converter could be greatly increased. Analysis and experimental results show that the proposed topology offers great advantages when the converter output current goes higher and the voltage goes lower, as demanded by future microprocessors and telecommunications systems. A 48-V/1.0-V, 100-A, 300-kHz prototype is implemented, and the experimental results show that it can achieve 87% efficiency at full load.     

DC／DC变换器中的噪声管理

零电流开关器件产生的谐波和寄生噪声较少,适合于噪声敏感型用途     

使DC/DC变换器限流特性线性化的热敏电阻器网络

最近推出的各种集成式降压DC/DC变换器均已采取对外接低侧MOSFET同步整流器的电压降采样的方法,无需高侧电流检测电阻器。这种拓扑节省了检测电阻器的成本和印制电路板的空间,也适当提高了电路效率。但是,MOSFET的导通电阻与温度有很大的相关性,它决定了限流大     

在300mV供电电压下工作的JFET DC／DC转换器

使用JFET的自偏置特性可以建立一个DC/DC转换器,它能用太阳能电池、热电偶和单级燃料电池等电源工作,这些电源电压都低于600 mV,有的甚至低至300 mV。     

A dc transformer

Although conventional transformers are ac, a device that may be termed a dc transformer has been constructed by using superconductors. To provide an understanding of how such a transformer would operate, some of the properties of type I and type II superconductors are reviewed. Since the dc transformer under discussion is constructed from thin superconducting films, the main emphasis is on these structures; the concept of flux motion is also explained. The result of the work described is a device in which a direct current or voltage can be transformed, and in which it is possible to extract power from the secondary circuit.     

新型引脚技术提升了DC/DC转换器的性能和可靠性

DC/DC转换器制造商C&DTechnologies公司(位于美国亚利桑那州图森)开发的PositionPerfect引脚技术消除了元件在组装时发生移动的可能性,从而使无引线SMTDC/DC转换器的机械安装整体性和精确性均有所提高。与传统技术相比,此项技术还能够使转换器引脚提供更高的电流,从而确保将满载的额定电流输送至主PC电路板上。该技术运用了SMT互连,这种SMT互连采用了由高速自动模锻工艺固定在转换器上的独特铜柱。在模锻处理之后进行的修剪形成了极端平整的表面,从而确保了引脚的共面误差小于0.004英寸,并且消除了元件的移动。将引脚固定在转换器…     

Submarine dc cables

Since 1900 most of our power has been supplied by alternating current, but the high-voltage electron tubes and the rectifying equipment developed during the last decade have revived our interest in direct current. Because geographical factors have made most of our present-day dc cables submarine, we find that we are beset by the same problems that were involved with their historical antecedents? transatlantic telegraph, and later telephone, cables. Mechanical problems arise because of the complex structure of a cable, and because of all of the stresses to which it is subjected. There is also the problem of electrical stress. A comparison of the various types of cable shows that rugged, lightweight equipment is desirable, and that taped insulation insures reliability.     

A prognostic method for predicting failure of dc/dc converter

The failure of dc/dc converters can directly result in electronic systems working unconventionally or significant downtime. To pre-determine time to failure and generate substantial safety and cost benefits, it is necessary to assess the extent of deviation of dc/dc converters from its expected state of health in real time and predict time to failure in advance. This paper presents a novel prognostic method for predicting the time to failure of dc/dc converters. The process involves identifying precursor parameters, determining prognostic of failure, and determining a criterion for predicting time to failure. The output voltage is used as a precursor parameter and directly monitored when the converter with a given load periodically operates at different temperature stresses. The phenomenon that the differences of output voltages collected at different temperature stresses begin to increase with a large (or small) fluctuation is detected in collected output voltages. This phenomenon is identified as a prognostic of failure. A percentage of the initial difference is used as the criterion for predicting time to failure. A case study is given to illustrate the procedure that how to monitor output voltages, detect prognostic and predict time to failure. The results show the health state could be assessed in real time and the time to failure could be predicted in advance. Furthermore, the deviation of the predicted time to failure from the actual time to failure could meet the demand of a considered acceptable range in engineering practice.