一种PWM/LDO双模同步降压型稳压器的设计

设计了一种新颖的外部同步信号控制PWM/LDO双模系统,用来提高系统在轻载下的性能。介绍了整个系统的整体框架和功能,并对切换电路进行了详细的分析与设计。在此基础上,基于华润上华0.5μm CMOS工艺,使用Cadence对整体电路进行仿真验证。结果表明,系统输入电压Vin的范围为3.6~6 V,输出电压VO为3.3 V,PWM信号工作频率为1.2 MHz,PWM模式下纹波小于30 mV,LDO模式下最大负载电流为50 mA、纹波电压小于10μV,在20 mA~1.2 A负载范围内,系统效率保持在80%以上,PWM/LDO双模切换稳定时间小于60μs。     

稳压性能优良的升压转换器

两个8脚IC组成的稳压器电路可把锂电池的3V输出电压转换成5V,并提供高达100mA的负载电流(见附图).它不靠电感器和变压器工作,静态消耗电流仅为200μA.当输入电压V_(in)=3V时,如果带100mA负载,其效率为81%;如果带20mA负载,其效率为84%.它的效率能随V_(in)的降低而增加.比如,当V_(in)=2.7V(该电池在大部分工作寿命期间的负载输出电压)时,40mA负载电流的效率为90%.锂电池(Duracell公司2/3-A号电池DS123A)的输出电压用大电流充电泵IC1增加一倍.肖特基二极管D1用来保证该电路的启动.D1不会影响效率,因为在正常工作时负载电流不从中流过.IC2是线性稳压器,当负载电流     

一种PWM/PFM自动切换的同步整流DC-DC芯片的设计

设计了一种降压式PWM/PFM自动切换的同步整流DC-DC变换器芯片,对其结构原理进行了分析,并用0.5μm n阱CMOS工艺进行模拟验证。Hspice模拟结果表明在输出负载电流为1mA,输入电源电压为3.6V,温度为25℃时,纹波电压为10mV,静态电流只有56.7μA,而待机工作模式下静态电流小于0.01μA,效率高达90%。体现其具有低功耗、低纹波、高效率的优点,且该变换器可工作在2~6V电源电压范围,可应用于各种便携式电子产品中。     

一种用于G类音频功放的带自适应输出的双模电荷泵

本文设计了一种给G类音频功率放大器提供自适应电源的双模电荷泵电路。根据输入信号的幅度,该电荷泵可以提供两档电压轨来节省功耗。它在重载下工作于电流控制模式,轻载下工作于脉冲频率调制(PFM)模式来降低功耗。在PFM工作模式下,引入功率管尺寸动态调整的技术来减小PFM模式下的输出电压纹波并防止开关频率进入音频范围。该电荷泵电路采用0.18μm,3.3V的CMOS工艺制备。试验结果表明该电荷泵在1/2x模式下可以实现79.5％的最高效率,在1x模式下可以实现83.6％的最高效率。在PFM控制模式下,电荷泵在负载电流小于120mA的范围内,其输出纹波小于15mV;在电流控制模式下,在负载电流小于300mA的范围内,其纹波小于18mV。测试结果与文中提出的功率分段的PFM控制模式的纹波、效率的解析模型得到的计算及仿真结果基本一致,验证了模型与分析方法的正确性。     

一种具有750mA输出电流,双模式PWM/PFM控制的高效率直流-直流降压转换器

提出了一种输出电流可达750mA,脉宽调制（PWM）和变频调制（PFM）双模式控制的,高效率、高稳定性直流-直流降压转换器.该转换器在负载电流大于80mA时,采用开关频率为1MHz的PWM工作模式;在负载电流小于80mA时,采用开关频率减小和静态电流降低的PFM工作模式,实现了在整个负载电流变化范围（0.02~750mA）内,转换器均保持高效率.而且采用一种快速响应的电压模式控制结构,达到了优异的线性和负载调整特性.芯片采用CSMC公司0.5μm CMOS 2P3M混合信号工艺物理实现.测试结果表明,该电路可根据负载的变化在PWM和PFM模式下自动切换.最大转换效率达96.5%;当负载电流为0.02mA时,转换效率大于55%.该芯片特别适合电池供电的移动系统使用.     

低输入高效率高可调性DC/DC转换器的设计

设计了一种基于0.6 μm BiCMOS工艺的低功耗、微功率、低输入、高输出、高效率、高可调性PFM升压型DC/DC转换芯片.分别采用高低压结合、预充电和抗饱和、固定关闭时间电流模式控制结构以达到低工作电压、高效率、高可调性和稳定的电压输出.本芯片采用XFAB公司的XB06工艺流片成功.测试结果表明,芯片的工作电压可低至1 V,无负载时静态电流仅为20μA,在输入电压/负载电流分别为1.5 V/15 mA、6 V/500μA的情况下能稳定地输出3.3、35 V,最高转换效率可达85%.     

一款高效率双模式降压型DC-DC转换器的设计

利用检测负载电流的大小来切换调制模式的方法实现了一种降压型高转换效率的DC-DC开关电源,其输入电压范围为4.5V～30V。轻载时芯片工作在跳跃模式,随着负载的增大芯片自动进入PWM模式。由于降低了轻负载和待机状态下的开关损耗,可延长电池的寿命和设备的待机时间。同时外部可调节的软启动有效减小了输入浪涌电流和启动时的输出过冲。该芯片在0.6μm CDMOS工艺进行投片验证,测试结果表明,在输出电压3.3V条件下,5mA负载下的效率不低于64%,最高效率可达95.5%。     

产品大比拼

LM3370是一款双通道降压DC／DC转换器,可用于驱动超低电压电路,只需单节锂离子电池和2．7～5．5V的输入轨电压范围。LM3370提供两个输出电压,每通道负载电流为600mA。输出电压范围在1～3．3V之间,可运用FC兼容接口进行动态控制。动态电压调整功能允许处理器在最低功率水平上实现最高性能。I^2C兼容接口能够用来控制自动PFM—PWM／PWM模式选择和其他性能增强的特性。     

一种峰值电流模式下的轻载高效Buck转换器设计

提出了一种峰值电流模PWM下的轻载高效Buck DC-DC控制方案,该方案采用了峰值电流开关和采样保持电路,实现宽负载范围内很高的转换效率.其中峰值电流开关用以检测负载电流大小,作为轻载或者重载模式的判定;采样保持电路会在轻载模式下工作,通过控制误差信号的变化量来循环开启或者关闭转换器,完成对转换器的开关频率调制.采用0.5μm BCD工艺,仿真结果显示在输入电压12V,输出电压3.3V下,最高有96%的转换效率,而在10mA负载下依然能保持80.3%的转换效率.     

采用DFN封装的I2C可控降压型稳压器

采用片上I2CTM接口,输出电压可用一个内部6位DAC设置在0.69V～2.05V之间。LTC3447的2.5V～5.5V输入电压范围使其非常适用于由单节锂离子电池或多节碱性/镍镉/镍氢金属电池供电的应用中为英特尔的xScale微处理器内核供电。LTC3447同步降压型稳压器能以高达93%的效率提供高达600mA的输出电流。其I2C接口频率可以设置到标准的100kHz或400kHz“快速模式”,同时输出电压能以21.6mV的分辨率编程。恒定1.0MHz开关频率确保低噪声并允许使用微小的表面贴装电感器和电容器。延长电池寿命的自动突发模式工作将轻负载电源电流降低至仅为33μA…     

A High Efficiency Dual-Mode Buck Converter IC For Portable Applications

This paper presents the design of a novel wide output current range dual-mode dc to dc step-down (Buck) switching regulator/converter. The converter can adaptively switch between pulsewidth modulation (PWM) and pulse-frequency modulation (PFM) both with very high conversion efficiency. Under light load condition the converter enters PFM mode. The function of closing internal idle circuits is implemented to save unnecessary switching losses. The converter can be switched to PWM mode when the load current is greater than 100 mA. Soft start operation is designed to eliminate the excess large current at the start up of the regulator. The chip has been fabricated with a TSMC 2P4M 0.35 mum polycide CMOS process. The range of the operation voltage is from 2.7 to 5 V, which is suitable for single-cell lithium-ion battery supply applications. The maximum conversion efficiency is 95% at 50 mA load current. Above 85 % conversion efficiency can be reached for load current from 3 to 460 mA.     

Design of high efficiency dual-mode buck DC-DC converter

A buck DC-DC switching regulator with high efficiency is implemented by automatically altering the modulation mode according to load current,and it can operate with an input range of 4.5 to 30 V.At light load current,the converter operates in skip mode.The converter enters PWM mode operation with increasing load current.It reduces the switching loss at light load and standby state,which results in prolonging battery lifetime and stand-by time.Meanwhile, externally adjustable soft-start minimizes the inru...     

A dual-mode fast-transient average-current-mode buck converter without slope-compensation

A dual-mode fast-transient average-current-mode buck converter without slope-compensation is proposed in this paper. The benefits of the average-current-mode are fast-transient response, simple compensation design, and no requirement for slope-compensation, furthermore, that minimizes some power management problems, such as EMI, size, design complexity, and cost. Average-current-mode control employs two loop control methods, an inner loop for current and an outer one for voltage. The proposed buck converter using the current-sensing and average-current-mode control techniques can be stable even if the duty cycle is greater than 50%. Also, adaptively switch between pulse-width modulation (PWM) and pulse-frequency modulation (PFM) is operated with high conversion efficiency. Under light load condition, the proposed buck converter enters PFM mode to decrease the output ripple. Even more, switching PWM mode realizes a smooth transition under heavy load condition. Therefore, PFM is used to improve the efficiency at light load. Dual-mode buck converter has high conversion efficiency over a wide load conditions. The proposed buck converter has been fabricated with TSMC 0.35 μm CMOS 2P4M processes, the total chip area is 1.45×1.11 mm². Maximum output current is 450 mA at the output voltage 1.8 V. When the supply voltage is 3.6 V, the output voltage can be 0.8-2.8 V. Maximum transient response is less than 10 μs. Finally, the theoretical analysis is verified to be correct by simulations and experiments.     

一种非隔离型LED照明恒流驱动芯片设计

实现了一种具有超高电压输入、高精度、大调光范围、低成本的非隔离型LED恒流驱动芯片。芯片采用外接高压三极管的电压调整结构以及高精度基准电压源,以PWM峰值电流控制方式实现了高精度、高一致性的电流输出。芯片采用18 V耐压的工艺流片,实现输入电压范围从10 V达到450 V变化,电能转换效率高达92%,驱动电流可从几毫安到超过1 A间设定,电流精度和一致性可达1.5%。     

双模式高集成负电荷泵电路设计

提出了一种新颖的双模式高集成开关电容电荷泵。该电荷泵集成高频振荡器、电平移位、逻辑驱动以及4个功率MOSFET开关。与传统电荷泵相比,该电路可以工作在单电源以及双电源两种模式。单电源模式下,输出电压为-VCC;双电源模式下,输出电压为-3×VCC。电路采用0.35μm BCD工艺实现。测试结果表明:室温时,单电源模式和双电源模式下电荷泵输出电流分别为36 mA和80 mA时输出电压分别为-3.07 V和-12.10 V。在-55℃到125℃温度范围内,单电源模式和双电源模式下电荷泵输出电流分别为24 mA和50 mA时输出电压分别低于-3.06 V和-12.35 V。该电荷泵在两种模式下工作特性良好,已应用于相关工程项目。     

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。     

A novel low quiescent current PFM method with independent threshold for buck switching converters

Efficiency is the key parameter of switching converters. Pulse frequency modulation (PFM) is often used to reduce the dynamic loss at the light load condition, while Pulse width modulation (PWM) is used in heavy load case. The efficiency at the heavy load is usually process dependent, however there are many circuits design considerations for the efficiency and other electrical performances improvement in the light load case. This paper will propose a method which can operate in the PWM in heavy load condition and automatically change to the PFM in light load condition with accurate PFM current threshold independent to input voltage, output voltage, switching frequency and inductor value. The adaptive accurate zero cross comparator (AAZCC) for DCM (discontinuous mode) and the method to achieve very low quiescent current consumption in the skip period are also introduced, those two are the points to further improve the efficiency in light or medium load conditions. A prototype has been designed with a 0.18 μm CMOS process.     

可实现DVS的单电感双输出降压型直流-直流转换器

设计了一款单电感双输出(SIDO)的降压型直流-直流转换器,一个输出电压可以进行动态电压转换,在0.725～1.2V直接变化,另一输出电压可实现1.2V和1.8V,两路输出最大可实现500mA负载电流。转换器根据负载的不同在脉冲宽度调制(PWM)和脉冲频率调制(PFM)之间自动切换。采用死区时间自适应调整的技术来提高系统的转换效率,分段开关则用来降低输出端毛刺。基于TSMC0.25μm CMOS工艺,测试结果证明该系统输出电压纹波低、毛刺小,系统峰值效率可达90%。     

采用分段式自适应PWM/PFM调制的Buck型DC-DC转换器设计北大核心

为了在轻重负载条件下获得更高的转换效率，采用分段式结构和导通电阻更小的NMOS作为输入级，并采用PWM/PFM双调制方式，设计了一种Buck型DC-DC转换器。为解决PWM/PFM调制信号切换问题，采用零电流检测方式进行切换。利用断续导通模式(DCM)和连续导通模式(CCM)下端NMOS管导通时电感电压的不同，检测下端NMOS在导通时电感电压大于零的周期。当电感电压大于零的周期大于2时，则处于DCM模式并自动采用PFM调制模式，关闭一部分功率管以减小开关频率和功率管寄生电容，优化轻载效率；反之则处于CCM模式并采用PWM调制。仿真结果表明，在负载电流10～1 000 mA范围内，该电路可以在两种调制模式平稳切换，在800 mA时峰值效率可提升到96%以上。     

0.25?μm 1.2?MHz BOOST-PFM-CONTINUOUS triple mode LED driver integrated in analog front end IC for portable application

This paper proposes a triple mode LED driver integrated with 16bit level sensitive analog front end by 0.25???m CMOS process for portable application. The LED driver needs to regulate single LED current with 0.9?C3.6 V_input voltage to support several types of battery. The output range is 2.5?C4?V which requires voltage step-up and step-down. A step-up/step-down converter can do this with a lot complexity, more components, lower efficiency and requirement of high voltage switches which adds extra manufacture cost. Our proposed topology avoids complicated step-up/step-down topology. It has triple modes: Boost PWM mode, PFM mode, LDO mode to cover different input voltage range. The mode control is implemented by simple circuit and gives smooth mode transition and very stable LED current. The simple topology makes it possible to use two stack 3?V IO devices as internal power switch to tolerate max to 5.7?V. By careful design and layout, LED switching activity only degrades the 16bit level analog front end SNR by 1?dB.