集成电路与半导体

安森美公司PFC控制器 安森美(ON Semiconductor)公司推出两款功率因数修正(PFC)控制器,针对输入功率在75W到3kW的应用而设计.NCP1653和NCP1601控制器非常适于如下设备电源的功率因数修正:电视、平板监视器、台式PC和笔记本适配器SMPS、离线充电器以及白色家电(如冰箱、洗衣机和干燥机).NCP1653是一种频率固定、电流模式PFC控制器,其设计可以有效地驱动中、高功率(100W到3kW)连续导通模式(CCM)升压变换器.     

便于功率因数校正的控制器NCP1601

临界导电模式(BCM)目前是满足中低功率应用中功率因数校正(PFC)稳压的最常用方案.但是,这种解决方案的开关频率的方差很大,使得在噪声敏感和大功率范围应用中实现BCM电路很困难.为了克服这个缺点,安森美半导体开发了一个创新的功率因数控制器-NCP1601,可以在固定频率和不连续导电模式(DCM)中工作.为了达到整功率因数,电路根据在先前开关周期中测得的死区时间长度调制功率开关导电时间.本文讲述NCP1601方案和功能.     

集成电路与半导体

安森美公司PFC控制器安森美(ON Semiconductor)公司推出两款功率因数修正(PFC)控制器,针对输入功率在75W到3kW的应用而设计。NCP1653和NCP1601控制器非常适于如下设备电源的功率因数修正:电视、平板监视器、台式PC和笔记本适配器SMPS、离线充电器以及白色家电(如冰箱、洗衣机和干燥机)。NCP1653是一种频率固定、电流模式PFC控制器,其设计可以有效地驱动中、高功率(100W到3kW)连续导通模式(CCM)升压变换器。除了输出电压固定模式外,它还可以工作在输出电压跟随输入电压变化模式,称为跟随升压模式。其功能特性包括:平均电流模式…     

以QR操作和软频率折弯为特征的单端PWM控制器NCP1205及其应用

NCP1205是安森美公司采用先进技术生产的一种单端脉冲宽度调制控制器。该控制器可保证在任何负载/线路条件下的完全继续传导模式(DCM)和准谐振(QR)操作 ,同时 ,该器件还组合了一个真正的电流模式控制调制器和一个退磁检测器。文中介绍了NCP1205PWM控制芯片的基本结构、工作原理和主要特点 ,给出了它的典型应用电路     

安森美半导体推出固定频率电流模式控制器

安森美半导体（ONsemiCondUCtor）推出NCP1237、NCP1238及NCP1288固定频率电流模式控制器集成电路（IC）。这些新控制器针对膝上型／笔记本电脑、液晶显示（LCD）显示器、打印机及家用消费电子的交流-直流（AC-DC）适配器应用,     

利用NCP1200和NCP4300A实现恒流恒压AC适配器

描述了利用电流模式PWM控制器NCP1200和次级反馈IC芯片NCP4300A构成恒流恒压（CCCV）AC适配器的巧妙设计。     

NCP1129等：开关稳压器

安森美半导体推出三款新的电流模式固定频率开关稳压器。NCP1129、NCP1126及NCP1124开关稳压器用于紧凑及高可靠性的离线AC—DC开关电源,包含额定雪崩能量650V MOSFET、提升轻载和待机能效的频率反走及跳周期模式,符合美国“能源之星（ENERGY STAR）”外部电源（EPS）2．0标准。     

高质量AB类音频放大器

NCP2991是AB类音频放大器，具有103dB的电源抑制比（PSSR），消除了电池电源电压波动可能产生的任何噪声。此外，这器件还确保启动和关闭时提供零“爆音（Pop）”和“嘀哒（Click）”声，适用于所有输入配置。这器件极低的（0．015％）典型总谐波失真（THD）进一步确保提供高保真音频输出。NCP2991的启动时间可在15～20ms之间选择。由于启动时间极快，NCP2991能够在未使用时保持关闭模式。因此，在大多数时间里，NCP2991仅消耗20nA电流。     

安森美半导体推出用于高能效紧凑型适配器方案的固定频率电流模式控制器

应用于绿色电子产品的首要高性能、高能效硅方案供应商安森美半导体推出了NCP1237、NCP1238及NCP1288固定频率电流模式控制器集成电路（IC）。这些新控制器针对膝上型／笔记本电脑、液晶显示器（LCD）、打印机及家用消费电子的交流．直流（AC-DC）适配器应用,提供不同频率及单或双过流阈值电平的选择。标准器件内置65kHz振荡器,     

6A降压DC／DC转换器

NCP6338提供范围为0．6～1．4V、增量为6．25mV的可编程输出电压,同时可采用低至2．3V的输入电压工作。这器件经过了优化,用于为平板电脑和智能手机等便携设备的先进应用处理器供电。NCP6338使用独特的模块化输出强度驱动,加上在脉宽调制（PWM）与脉频调制（PFM）模式之间自动转换的功能,能够根据负载调配其能效性能,因而节省电池电量。     

A digitally controlled PWM/PSM dual-mode DC/DC converter

A digitally controlled pulse width modulation/pulse skip modulation(PWM/PSM) dual-mode buck DC/DC converter is proposed.Its operation mode can be automatically chosen as continuous conduction mode (CCM) or discontinuous conduction mode(DCM).The converter works in PSM at DCM and in 2 MHz PWM at CCM.Switching loss is reduced at a light load by skipping cycles.Thus high conversion efficiency is realized in a wide load current.The implementations of PWM control blocks,such as the ADC,the digital pulse width modulator(DPWM) and the loop compensator,and PSM control blocks are described in detail.The parameters of the loop compensator can be programmed for different external component values and switching frequencies, which is much more flexible than its analog rivals.The chip is manufactured in 0.13μm CMOS technology and the chip area is 1.21 mm~2.Experimental results show that the conversion efficiency is high,being 90%at 200 mA and 67%at 20 mA.Meanwhile,the measured load step response shows that the proposed dual-mode converter has good stability.     

连续导电模式下的单电感双输出开关变换器

文章系统地分析了单电感双输出DC—DC变换器结构,采用分时复用原理实现双路输出。由于电感共享,各输出支路间存在着严重的交叉影响。当输出支路严格工作在不连续导电模式（DCM）或伪连续导电模式（PCCM）下,可有效抑制交叉影响。文章首次提出了应用于连续导电模式工作的单电感双输出开关变换器的峰值电流-差模电压控制方法,在连续导电模式（CCM）下实现了几乎没有交叉影响的双路输出。     

斜坡补偿Buck变换器工作状态域估计

 通过建立含斜坡补偿的分段光滑迭代映射方程,导出了电流控制型Buck变换器运行轨道状态发生转移时的两个分界线方程,由此确定了其工作状态的区域.Buck变换器参数空间映射图的仿真结果验证了由两个分界线方程估计其工作状态域的正确性.开关变换器工作状态域的估计对电路参数的合理选择以及混沌的镇定控制有着实际的指导意义.     

Digitally controlled boost power-factor-correction converters operating in both continuous and discontinuous conduction mode

Whereas power-factor-correction (PFC) converters for low-power ranges (less than 250 W) are commonly designed for operation in the discontinuous conduction mode, converters for higher power levels are operated in the continuous conduction mode. Nevertheless, when these converters are operated at reduced power, discontinuous conduction mode will appear during parts of the line period, yielding input current distortion. This distortion can be eliminated by employing a dedicated control algorithm, consisting of sample correction and duty-ratio feedforward. The reduction of the harmonic distortion of the input current and the increase of the power factor are demonstrated by experiments on a 1-kW boost PFC converter.     

反激型光伏微型逆变器不同工作模式的分析与比较

反激型光伏并网微型逆变器工作模式有不连续导通模式（DCM）和连续导通模式（CCM）两种。在工作原理的基础上,文中通过对这两种工作模式的分析和研究,推导了两种模式下逆变器主要参数的计算公式,从不同方面对两种模式的优缺点进行了对比分析,并得出相应结论,为根据设计要求合理选择逆变器的工作模式提供了理论依据。     

Application of the time-varying transfer function for exactsmall-signal analysis

An analysis method for determining the control-to-output linearized describing function of time-interval-modulated switched networks using time-varying system theory was previously proposed by the author. A simplification is now presented which eases the analysis considerably. Use of the simplified approach is demonstrated in the derivation of the control-to-output frequency response of pulse-width-modulated (PWM) DC-to-DC switching power converters operating in discontinuous conduction mode (DCM) and current programmed converters operating in continuous conduction mode (CCM) as well as in DCM. Experimental results are presented which verify the modeling approach     

反激式开关稳压电源传导干扰研究

开关式直流稳压电源的电磁干扰不仅对电网产生干扰,导致在同一电网上供电的其它设备不能正常工作,而且严重的谐波电压电流会在开关电源内部产生电磁干扰,从而造成开关电源内部工作不稳定,使开关电源性能降低。文中以反激式开关稳压电源为研究对象,主要分析了传导测试中,差模、共模传导两种方式噪声源的产生机理,建立了开关电源传导干扰模型,采用EMI滤波器即共模滤波和差模滤波,并详细研究了加入π型滤波器、输入x电容、共模扼流圈等对开关稳压电源传导干扰的抑制效果,得出传导干扰抑制在标准限制范围的改进措施,整改后可让传导干扰强度从100μV降低到200 nV并通过认证。研究结果表明该措施对抑制开关稳压电源传导干扰是有效的。     

The overall small-signal model of the synchronous switchpostregulator

The overall small-signal models of the synchronous switch postregulators (SSPRs) with leading-edge or trailing-edge modulation are developed. From the models, the effect of the main output to the auxiliary output when the SSPR is operated in the continuous conduction mode or in the discontinuous conduction mode can be predicted. Once the main output enters into the discontinuous mode, the performances of the auxiliary output will degrade very much, even with the help of the postregulation, but if only the auxiliary output enters into the discontinuous mode, the performance degradation of the auxiliary output can be less severe     

A refined nonlinear averaged model for constant frequency currentmode controlled PWM converters

A refined, duo-mode model for current programmed buck power converters is presented. The refined model uses a form of the current mode control law which is truly invariant with respect to operating conditions. That is, it is valid for both transient and steady-state operating conditions regardless of the converter operating mode, which could be either continuous conduction mode (CCM) or discontinuous conduction mode (DCM). The large-signal transient response predicted using the refined average model is shown to be virtually indistinguishable, in an average sense, from that predicted using a pulse-by-pulse simulation. The refined model is shown to exhibit improved high-frequency accuracy in both time and frequency domains. The model has been implemented in SPICE 2G6 and runs with default analysis options     

Sampled-data modelling and analysis of the power stage of PWM DC-DC converters

The power stage of the PWM DC–DC converter is modelled and analysed using the sampled-data approach. The work addresses both continuous and discontinuous conduction mode under voltage mode control, and continuous conduction mode under current mode control. For each configuration, nonlinear and linearized sampled-data models, and control-to-output transfer functions are derived. Using this approach, both current mode control and discontinuous conduction mode can be handled systematically in a unified framework, making the modelling for these cases simpler than with the use of averaging. The results of this paper are similar to results of Tymerski, but they are presented in a simpler manner tailored to facilitate immediate application to specific circuits. It is shown how sampling the output at certain instants improves the obtained phase response. Frequency responses obtained from the sampled-data model are more accurate than those obtained from various averaged models. In addition, a new (‘lifted’) continuous-time switching frequency-dependent model of the power stage is derived from the sampled-data model. Detailed examples illustrate the modelling tools presented here and also provide a means for comparing results obtained from the sampled-data approach with those obtained from averaging.