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主题: 飞思卡尔™电源管理解决方案
在线问答:
[问：]	热插拔子卡的设计中，由于底板系统在子卡插拔时部分总线仍然处于工作状态，对于这样的热插拔设计需要注意一些什么？
[答：飞思卡尔]	子板总线的工作电压应该是子板提供的, 当您插拔子板时, 工作电压由MC34652/3提供, 瞬间的涌入电流由它们控制, 不会损坏负载子板。
[问：]	飞思卡尔的电平转换器对电源的加电顺序有何影响? 应如何考虑?
[答：飞思卡尔]	This would not impact your power sequencing unless it yanks down your power lines of either your IO or core voltages. Even if this does happen, the power sequencing if active, will ensure the sequencing is proper. If this does not answer your question, pls enquire with Freescale regional FAE.
[问：]	飞思卡尔的电源管理相对于其他公司的同类产品有何不同的特点和优势?
[答：飞思卡尔]	Freescale solution can provide reduced system level (BOM) cost and can save PCB space saving. Also, some cost competitiveness. Freescale's power saving mode is ideal for handheld powered. This product can improve overall regulation.
[问：]	飞思卡尔的MCU对上电和掉电顺序很敏感吗？错误的顺序会导致什么后果？
[答：飞思卡尔]	It depends on which MCU or processor, you need to check with the datasheets. To give you an example, for our PowerQUICC1 2 processors (Power PC) they need power sequencing. For the PowerQUICC3, this does not. The wrong sequencing could mean that the core voltage is undefined when it is receiving valid digital inputs to the processor and this could be a problem.
[问：]	LDO方式和开关电源方式在芯片内部的电压变换和功能实现上是如何划分的？
[答：飞思卡尔]	对于使用飞思卡尔的芯片, 你可以不用过分关注于是SW提供还是LDO提供的供电只需要注意您的负载电流和不同的输出电压。 SW和LDO的工作原理不同, 很难在这里讲清楚。请参考飞思卡尔本次座谈里的内容或其它著作。在线座谈: http://www.freescale.com.cn/webcast/Analog/PowerManagementSolution.asp
[问：]	MC34652最大能承载多大的瞬间电流?
[答：飞思卡尔]	MC34652 has a short circuit current limit funtion. Its maximum current is 5A. If the current is greater than 5A (>5A), the power MOSFET is discharged very fast (<10uS) and MC34652 is in overcurrent mode for 3.0mS. Please refer to data sheet page 11~12 overcurrent mode and short circuit mode.
[问：]	MC34703能承受多大的瞬间电流?
[答：飞思卡尔]	19A
[问：]	按照负载点拓扑图方式, 在拓扑点, 飞思卡尔有哪些外围元件最少的电源管理芯片, 比如提供3.3V,1.8V?
[答：飞思卡尔]	这在线座谈飞思卡尔介绍的芯片, 和飞思卡尔的电源管理器件都对外围元件需要较少。请参考飞思卡尔的选购指南获得其它的产品信息。
[问：]	不知道有没有升压型、降压型一体的开关电源芯片，具体型号是什么？
[答：飞思卡尔]	Freescale provides both buck and boost regulators but are on more sophisticated devices. For example, Freescale's portable 18730 device. For simplier ones, Freescale has not released them yet, stay tunned for this.
[问：]	电源的噪声有多种定义如uVrms, V/rtHz, 还有dBc/Hz, 它们有什么不同? 那种最能反映电源的噪音性能?
[答：飞思卡尔]	This is not concerned with the power supply but is relating to it, though not entirely as it depends on noises from your other components. In general, noise is a measure of energy over a frequency range. So you would see this with per Hertz. If you have uV/Hz then it means the voltages of noise for 1 hz. You then multiply this with the bandwidth of interests. dBc is the power level reference to the carrier signal. This is with RF, not the power supply. Vrms is Voltage root mean square value. It is the equivalent dc level of an ac voltage. You need to read up from reference material on this.
[问：]	负载点是怎么划分的？
[答：飞思卡尔]	1st you need to know your power budget requirement and then the load requirements of each point in your system that you want to power. This would depends on the ripple voltage, line, load requlations, power output etc. Once you have the characteristics of the load then you pick your power supply that can cater for this requirement. If you go to Freescale power management solution webcast, an example is given of a 3G system. Also a design example is given for a specific load requirements. Webcast replay: http://www.freescale.com.cn/webcast/Analog/PowerManagementSolution.asp
[问：]	开关电源和LDO有什么区别？
[答：飞思卡尔]	简单的说，开关电源是通过PWM控制的，可以通过不同的频率和占空比来获得电压。它不是连续的。 LDO是连续输出的，一般只能提供比输入电压低的输出电压。在飞思卡尔这次的座谈中，有对开关电源和LDO的讨论。
[问：]	开关电源或线性电源的输出电压和输入电压相差较大时, 是否效率就降低?
[答：飞思卡尔]	For LDO regulator, the answer is Yes. But for switching regulator, the efficiency is not dependent on voltage difference.
[问：]	开关电源模块的地和线性稳压模块的地怎么处理为好？
[答：飞思卡尔]	一般需要在输出端加滤波电容。可以参考飞思卡尔的芯片数据手册，内部有详细的介绍。
[问：]	可否采用瞬态电压抑制器来应付负载突降?
[答：飞思卡尔]	It depends on which device you are talking about from the webcast. Freescale dc-dc convertor is designed to handle transient surges and we do have special devices incorporated to handle high surges like the hotswap controllers. But if you were to add in an external suppressor, you need to be concerned with the response time and whether this will deprive the power to your load. Pls consult with Freescale local FAE if you need help.
[问：]	我们现在要实现一个系统, 由于历史的原因, 需要3V, 1.8V, 5V, 3.3V, 2.5V的电源支持, 请问飞思卡尔有没有一个芯片解决这个问题的方案？如此复杂的系统, 在布线方面有什么技巧吗？
[答：飞思卡尔]	您可以根据您的不同工作电压，在不同的位置，可以考虑使用飞思卡尔的电源芯片。飞思卡尔不仅仅提供本次座谈中提及的MC34701/2/3，飞思卡尔还有其它的LDO和开关型电源芯片。请访问飞思卡尔的网页 http://www.freescale.com.cn/Products/analog.asp 或和当地的飞思卡尔，代理商联系获得帮助。飞思卡尔代理商联系信息 (按地区检索或按名录查询): http://www.freescale.com.cn/others/wheretobuy/
[问：]	我想了解一下飞思卡尔的ldo的最低压差是在多少？
[答：飞思卡尔]	50mv.
[问：]	飞思卡尔有没有控制下电时序的方案？
[答：飞思卡尔]	Freescale QUICCSupply can provide both power up and down sequencing, whether standard or inverted. You just need to program or select this sequence using 2 enable pins provided by the device. For the actual specification pls go to Freescale website and download the datasheet for this.
[问：]	a. POL电源主要应用于何种场合? b. 使用POL电源应注意那些问题?
[答：飞思卡尔]	Just to clarify, POL is Point of load and is a method of power management. It is not a power Supply. POL can be applied to any systems whether it is complex or simple. In fact the more complicated your system power is, the better this scheme would benefit you. You will have better EMC, better regulation, transient response and less IR losses. When using POL, you need to pay attention to the total loading that each PoL will have on your main power, or your Brick supply.
[问：]	我在做硬件设计的时候，经常遇到关于电源的问题是：功率和纹波系数的问题？请问，现在技术在这两方面有什么新的突破没有？另外, 如果工作温度从-50度至150时，要求电源仍有优良的稳定性和精度，现在国际比较领先的在这方面能做到什么程度？
[答：飞思卡尔]	Most of our devices are for temp range -40 to 85degrees. If you want outside this range then you need to consult with Freescale sales office to help. It seems you are searching for automotive grade supplies. Freescale group is with Industrial and consumer grade. For your 1st question, we have very high power efficiency using Pusle skip mode in our 18730 device for a wide load range. But for Freescale other devices that do not require this, Freescale has not incorporated this. For ripple factor on the input or output, you need to consider both the converter and the board components like the Output cap’s ESR etc.
[问：]	请问ldo 降压差调节器的主要应用环境？它的间断性供电会不会给系统造成影响，比如说噪声什么的?
[答：飞思卡尔]	LDO provides stable and low-noise output voltage source, but poor efficiency. So LDO is suitable for no power-saving concern application.
[问：]	请问为何有些处理器没有上电顺序的问题呢? 上点顺序是否可以在处理器设计上予以解决呢?
[答：飞思卡尔]	There are many reasons. Some are not concerned with the undefined core voltages because they have some initialization state within the processor, while others may have their own power sequencing built in. To solve this, you can use Freescale chip by direct plug in, and no need to concern with this aspect. Or you need to stick in 2 diodes with appropriate power rating to solve this.
[问：]	如何解决上电顺序和EMC考虑，另外在电源功耗上是怎样解决的？
[答：飞思卡尔]	For Power Sequencing, there are several ways: 1st can use our chip and it will do the job for you but you must makesure that this power sequencing is compliant to your processor. Freescale is for the PowerQUICC processor and should be good for many others. The other way is to use external components like 2 diodes. For EMC, this is more complicated, you need to have good isolation and guarding between your switching signals and how power signals away from your more sensitive nodes (inputs and outputs). Power consumption would depend on the type or power supply topology that you are using. A good measure is in the power efficiency and not the power consumption. This is a very broad topic and is not the focus of this topic.
[问：]	什么是动态功率管理功能? 飞思卡尔的电源效率能达到多高? 影响电源效率的因素有多少?
[答：飞思卡尔]	由於不同的产品达到不同的电源效率。
[问：]	使用LDO的时候如果输入和输出压差较大芯片发热量会不会很大？
[答：飞思卡尔]	No, the package doesnt need heat sink for the issue.
[问：]	我们的系统需要5V，3.3V,1.8V,1.5V供电，其中5V的负载很轻，电流只有几个mA，而3.3V 的负载电流有几百mA。输入电压为28V，请问是用28V/5V，再5V/3.3V等分级转换，还是分负载点直接转换？飞思卡尔有这样的产品解决方案么？
[答：飞思卡尔]	飞思卡尔的器件可以提供1路5V/3.3V输出和1路1.8V/1.5/V输出。如果使用5V/3.3V分极转换可能需要的芯片会增多，功耗增大，使用负载点的方案可能更好些。您的5V负载很轻，可以考虑使用其它方式来实现。可以考虑飞思卡尔的MC34710芯片。
[问：]	我们现在的项目是无线传感器网络，它对电源的要求非常严格！因为是一次性的，所以对于电源的使用要有很多的节能方案。不知道飞思卡尔有没有这方面应用的解决?
[答：飞思卡尔]	本次飞思卡尔座谈只介绍了一款电池供电产品，MPC18730。您可以先根据您的具体要求比照MPC18730，看是否满足需要。还有您可以访问飞思卡尔的网站获得更多的无线产品和解决方案。http://www.freescale.com.cn/Products/analog.asp
[问：]	我是做STB产品方案设计的，需要把5V的电压降压为3.3V/600ma、1.8V/600ma，应该采用那一款芯片合适，大概成本如何？目前我使用的是1085两块。
[答：飞思卡尔]	MC34710可以提供两路输出，但是1.8V的输出仅提供500mA的电流。您看是否可以满足需要。如果使用MC34701的话可以完全满足您的需要。
[问：]	我需要一种6V～60V宽输入范围, 输出5V～1.2V的电路, 能否推荐一款飞思卡尔的产品。
[答：飞思卡尔]	Recommend MC34129 (MC33129) PWM controller and apply Flyback topology. The solution can meet your requirement.
[问：]	希望给我们一个12v300mA低成本小体积高可靠开关电源方案？
[答：飞思卡尔]	您是指12V输出吗。飞思卡尔目前提供的输出电压都低于12V。如果您需要12V输入，其它电压输出的话，请和飞思卡尔当地的工程师联系。
[问：]	用硬件信号能控制电源以实现对负载的电源关断和自动重启么？
[答：飞思卡尔]	Yes.
[问：]	在负载出现短路或断路情况，电源管理芯片有自我保护功能吗？过去采用linear的芯片，曾出现烧DC/DC芯片的情况。
[答：飞思卡尔]	Yes, Freescale power management solution provides overcurrent protection.
[问：]	在应用于DVB/数字电视方面，有什么特别推荐或是优势产品？
[答：飞思卡尔]	请比较飞思卡尔芯片提供的输出方式，输出电压，输出电流，输出的路数，等等，根据您的产品具体需要才能够选择合适的型号。
[问：]	在热插拔设计中，如果母板和子板各自是一个工作系统，两者的电源是由同一电源模块输出的，子板的插拔造成了电源负载的剧烈变化（子卡的功耗较大), 对母板来说，会造成什么样的影响，如何减小这种影响？
[答：飞思卡尔]	This is why you need to have a hotswap controller to limit the in-rush current on your motherboard. The exact reasoning applies of that from the backplane. Since the daughter card draws most of the current, removing it will create spikes on your motherboard. You need to have protection circuitry to prevent damages to your onboard components. Freescale hotswap will provide this function for you.
[问：]	MC34701对比LT1941EFE在静态功耗上有什么优势？LT1941EFE在静态功耗也有几个毫安，MC34701会不会更好？
[答：飞思卡尔]	MC34701的静态指标可以参看datasheet，34701可以提供一路开关电源，1.5A的驱动电流。和一路LDO。同时针对处理器的特点，提供安全的上电和下电控制，确保处理器正常工作。
[问：]	刚才我又看到PPT中有关给PROTABLE供电的芯片背面有不规则的焊盘那是做什么用的呢？散热吗?
[答：飞思卡尔]	Those pads that are in the middle are for Freescale internal testing purposes and are to be left alone and disconnected.
[问：]	飞思卡尔提供免费样片吗?
[答：飞思卡尔]	请跟飞思卡尔代理商联系 (按地区检索或按名录查询): http://www.freescale.com.cn/others/wheretobuy/ 或到飞思卡尔免费样品网站进行申请: http://www.freescale.com/webapp/sps/site/overview.jsp?nodeId=010984007869597059286929489
[问：]	降压调节器的主要应用场合是什么？
[答：飞思卡尔]	当要求的供电电压与供电电源电压不同时，都可能需要使用电压调节器。
[问：]	开关电源或线性电源的输出电压和输入电压相差较大时, 是否效率就降低?
[答：飞思卡尔]	Ldo efficiency will be affected (drop) if the drop out voltage is increased (Vin-Vout). This is directly proportional to the efficiency. Switcher will be affected by the Inductor on-off cycle time. This duty cycle will affect the efficiency as it determines the ontime of the charging of the external components and hence the switching loss. For instance, if Vout is very small, the on time for charging to the inductor is less but the discharging path is longer. One would need to conduct analysis along this path and understand the current losses with respect to each components during the on and off cycles. Nevertheless, the bigger the difference between Vin and Vout, the more efficient it is to use the switcher as oppose to the LDO.
[问：]	开关是稳压块效率受他的周围电路影响大吗？
[答：飞思卡尔]	This depends on what the other components are. If the components belong to the switcher this will affect the efficiency. For instance, the DCR of the inductor, or the free-wheeling diode will both affect the switcher's efficiency.
[问：]	哪一款电源芯片适合MCF5275，这些芯片是否已经量产？
[答：飞思卡尔]	飞思卡尔介绍的MC34701/2/3都可以给它供电，关键看您的产品对电源的需求。请参看他们的datasheets。关于芯片的供货情况，请和飞思卡尔的销售或代理商联系 (按地区检索或按名录查询): http://www.freescale.com.cn/others/wheretobuy/
[问：]	你们这几种电源芯片的功耗参数是多大？
[答：飞思卡尔]	Power consumption would depend on which device you are talking about and what loading you are applying to the circuit as well as what the input signal is. You need to refer to the datasheets and look this up for the max and minimium. To give you an example, if you are applying a low Vin verses that of a high Vin to the buck switcher then the device itself will consume more power for the low Vin because it needs to turn on the booster circuitry inside the chip. This is assuming that the loading is the same for both cases.
[问：]	请透漏MC34703的供货价格范围。
[答：飞思卡尔]	请跟飞思卡尔代理商联系 (按地区检索或按名录查询): http://www.freescale.com.cn/others/wheretobuy/ 或参阅飞思卡尔MC34703网页: http://www.freescale.com/webapp/sps/site/prod_summary.jsp?code=MC34703&nodeId=01435974403526
[问：]	请问飞思卡尔电源管理主要用于哪些产品上面？
[答：飞思卡尔]	飞思卡尔电源管理产品适用于汽车、电信、工业和消费类产品。
[问：]	请问飞思卡尔能提供整套方案吗，包括周围器件？
[答：飞思卡尔]	飞思卡尔只提供 IC。
[问：]	请问什么是开关电源，它与线形电源有什么区别?
[答：飞思卡尔]	A switching power supply is one that chops up the output current to the load and maintains the output voltage by this chopped up load. This uses an external inductor to provide the current on one part of a duty cycle and allowing the switcher FET to be turned off during the latter part to minimize power loss. This is why a switcher has higher efficiency. An LDO, lowdrop out regulator is a liner regulator that directly drops the voltage across the FET and in turn providing the required output voltage. The greater you drop the voltage, the higher the loss. There are trade offs with these 2 types of supplies in terms of regulations, ripples, losses and efficiencies etc.
[问：]	我的电路设计需要5v/1A的电流，有现成的集成元器件吗（输入为6V)?
[答：飞思卡尔]	飞思卡尔的MC34701可以提供1.5A的电流，同时还具有上电和下电控制功能和其它保护功能。
[问：]	用于便携式产品，有何推荐电源方案？
[答：飞思卡尔]	在本次座谈中飞思卡尔介绍了一款飞思卡尔的电源管理产品，适合单电池供电。请您参看本次座谈的内容。
[问：]	有可调1~10A的电流反馈（负载电阻在5~10间随机变化）低成本开关电源方案吗？年用量3~5万个/年。
[答：飞思卡尔]	MC34703可以提供10A电流的输出。

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