飞思卡尔最新DDR电源和DC-DC转换器在线座谈常见问题解答
 

在线座谈主题：飞思卡尔最新DDR电源和DC-DC转换器
[ 问题 1 ] DDR2/3超频时，你们的建议方案？
[ 答案 1 ] We don't recommend to use the product in non-standard conditions.
[ 问题 2 ] DDR3显存的延迟时间(CAS latency)一直是高频率显存的一大通病，飞思卡尔的这个延迟时间可以做到多少？
[ 答案 2 ] CAS Latency is the time it takes between the processor asking for some data from the memory and the memory returning it.
This product series apply for power management for the DDR memory only and CAS latency is handling by the memory controller.
[ 问题 3 ] DDR存储器速度对电源有些什么特别的要求？飞思卡尔的DC/DC转换器能否用于QDR存储器？
[ 答案 3 ] 只要DDR电源的输出符合DDR标准的规范，任何速度的标准DDR存储器都可以通过此电源正常供电。可以同时支持QDR存储器。
[ 问题 4 ] DDR的VTT和VDD有些什么差别？
[ 答案 4 ] VDD is the input voltage for the system. It allow a voltage range input. VTT is the controlled output voltage to support the memory.
[ 问题 5 ] EMI问题怎么考虑？ 提供参考PCB设计吗？
[ 答案 5 ] EMI的抑制主要通过减小开关过程当中产生的高频振荡来解决，您可以在PCB设计中，尽量使电感靠近芯片，同时使用低辐射的电感封装。飞思卡尔提供demo板供客户参考，具体可联系销售部或代理商。
[ 问题 6 ] 飞思卡尔那些产品具有VREF输出？ 幅度是多高？ 输出精度呢？
[ 答案 6 ] MC34712 and MC34716 have VREF output. The accuracy is 1%.
[ 问题 7 ] If I develop my PCB with a precise type of DDR2 memory like DDR2 Micron 200MHz 256Mb, will I risk to have problems with EMI and timing signals if I change of manufacturer or memory size?
[ 答案 7 ] The risk would be minimial or none at all if you adopt the standard practice of PCB layout. For instance, trace signal lengths are made short and away from sensitive and fast switching sources. It is assumed no other things are changed like voltages, placement of other blocks etc.
[ 问题 8 ] MC34712或MC34716系列器件的工作温度范围？
[ 答案 8 ] Our temp range is between -40 to 85C.
[ 问题 9 ] MC34712或MC34716系列器件工作稳定性都会受到哪些因素影响？
[ 答案 9 ] 这两个IC 是高品质的设计，对外部的干扰有很强的免疫力，只要不要超过此IC 的规格规范不会有这些问题，一般Switching IC 要注意外部的稳定度设计如 L, C, 值,及Layout 上注意噪声等。
[ 问题 10 ] MC34712或MC34716系列器件性能受温度影响大吗？
[ 答案 10 ] Operation temperature is -40~85 C degree. 只要此范围在 几乎不受温度影响。
[ 问题 11 ] MC34712可以进行上电时间顺序可编程吗？
[ 答案 11 ] The MC34712 has a tracking and sequencing block that allows the output of the MC34712 to track 1/2 the voltage applied at the VREFIN terminal. This allows the VREF and VTT voltages to track 1/2 VDDQ and assures that none of them will be higher than VDDQ at any point during normal operating conditions. For power down during a shutdown (S5) mode, the 34712 uses internal discharge MOSFETs (M5 and M6 on Figure2, Page2) to discharge VTT and VREF respectively. These discharge MOSFETs are only active during shutdown mode. Using this block along with controlling the SHTD and STBY terminals can offer the user power sequencing capabilities by controlling when to turn the MC34712 outputs on or off.
[ 问题 12 ] MC34712驱动能力有多大？能同时驱动多片DDR SDRAM 吗？
[ 答案 12 ] Driving current 3A 一般VTT 电流都很小DDR 1GB 的vtt 不会超过2A 所以可支持。
[ 问题 13 ] MC34712提供了VTT，与内部集成了VTT电源的DDR控制器相比有什么优势？
[ 答案 13 ] MC34712已提供VTT。所以它就不必再外加一组VTT电源，可节省PCB空间。
[ 问题 14 ] MC34712系列在抗过压和噪声及热保护上有哪些优势？
[ 答案 14 ] These device offers: O/P overvoltage can be as high as 8V. The Output Overvoltage and Undervoltage blocks monitor the buck converter output voltage to ensure it is within regulation boundaries. If not, this block alerts the system control for further commands.
Over Current Limit and Short Circuit Detection block monitors the output of the buck converter for over current conditions and short circuit events and alerts the system control for further command.Thermal Limit Detection block monitors the temperature of the device for overheating events. If the temperature rises above the thermal shutdown threshold, this block will alert the system control for further commands.
Please read our datasheet to understand more.
[ 问题 15 ] MC34712与MC34716输出电压精度调节是用何方式来调节的？
[ 答案 15 ] This accuracy is provided by our device. The MC34712/6 utilizes a voltage mode synchronous buck switching converter topology with integrated low RDS(ON) (45 m?) N-channel power MOSFETs and a high dc gain stage to provide an accurate output voltage.
[ 问题 16 ] MC34716的电源效率能达到多高？
[ 答案 16 ] This depend on the load of your board and can be up to 95%.
[ 问题 17 ] MC34716的散热情况如何，layout时是否有要注意的地方？
[ 答案 17 ] MC34716虽然集成了MOSFET，但是由于效率较高，芯片的发热仍然可以得到控制。而且内置的过热关断保护功能可以防止系统因为thermal runaway而造成的损坏。Layout是，注意将QFN封装的底部thermal pad充分与PCB板接触，可以通过打一些过孔到PCB板的另一面来帮助散热。
[ 问题 18 ] MC34716是否具有控制功能？
[ 答案 18 ] 当然有控制功能 。
[ 问题 19 ] MC34716是如何保证电压的1％精度的？
[ 答案 19 ] The MC34716 utilizes a voltage mode synchronous buck switching converter topology with integrated low RDS(ON) (45 m?) N-channel power MOSFETs and a high dc gain stage to provide an accurate output voltage.
[ 问题 20 ] MC34716有那些节电模式和保护功能？
[ 答案 20 ] For power saving mode, we have a buck topology that can attain very high efficiencies that’s in the nineties range. For protection, we have:-O/P overvoltage can be as high as 8V, The Output Overvoltage and Undervoltage blocks monitor the buck converter output voltage to ensure it is within regulation boundaries. If not, this block alerts the system control for further commands.
Over Current Limit and Short Circuit Detection block monitors the output of the buck converter for over current conditions and short circuit events and alerts the system control for further command.
Thermal Limit Detection block monitors the temperature of the device for overheating events. If the temperature rises above the thermal shutdown threshold, this block will alert the system control for further commands.
Please read our datasheet to understand more.
[ 问题 21 ] MC34716与MC34164的主要区别是什么？
[ 答案 21 ] MC34164 is a undervoltage sensing device, and is entirely different to our DDR supply device.
[ 问题 22 ] MC34716在解决电磁干扰方面采取了哪些措施？
[ 答案 22 ] 电磁干扰主要是由于DCDC工作当中产生的高频的振荡引起的，而SW点的ringing是很重要的一个干扰源。MC34716通过优化内置MOSFET的开关速度，使SW点的ringing减小的最小的程度。当然，使用辐射小的电感封装，以及尽量缩短芯片到电感的布线长度都是芯片以外解决电磁干扰问题的一些常用手段。
[ 问题 23 ] VREF/VTT 输出电压精度对DDR存储器的性能有什么影响？
[ 答案 23 ] VREF和VTT的电压精度对于DDR存储器的性能有很大的影响。VREF和VTT精度恶化时，会使DDR传输数据的timing发生改变，影响到正确的时序。具体可参考presentation的第12、13页。
[ 问题 24 ] What the Freescale regulators can offer to have save power supply for the memory?
[ 答案 24 ] Power saving is derived in 2 main ways: either through the high performance of your device when conducting (ie high efficiency) or through your system power saving scheme. Our device offers efficiency up to 95% thanks to the low RDson integrated FETS and the synchronous topology of our regulators. It also provides for standby and shutdown modes to help save system power when these devices are not called for action.
[ 问题 25 ] 采用开关电源和线性低压降稳压器给DDR供电，有些什么差别？飞思卡尔提供的DC/DC转换器属于那类？
[ 答案 25 ] 线性低压降稳压器，功率耗損大，效率很差。开关电源 (Switching Regulator) 效率高，飞思卡尔提供高品質的switching IC。
[ 问题 26 ] 都支持哪些通讯接口？
[ 答案 26 ] 它只是一个单纯的电源供给，所以没有通讯接口的问题，任何需要 DDR vtt电源都可以用。
[ 问题 27 ] 端电阻怎么计算，还是有一个固定的值？
[ 答案 27 ] Termination resistance depends on the sink and source current need for the memory system. You can reference the DDR system level diagram in our datasheet.
[ 问题 28 ] 对于电源的省电模式要求，飞思卡尔的电源是如何来实现的？
[ 答案 28 ] Power saving is derived in 2 main ways: either through the high performance of your device when conducting (ie high efficiency) or through your system power saving scheme. Our device offers efficiency up to 95% thanks to the low RDson integrated FETS and the synchronous topology of our regulators. It also provides for standby and shutdown modes to help save system power when these devices are not called for action.
[ 问题 29 ] 对于开关模式的DC-DC 转换器，在设计中需要注意哪些问题？
[ 答案 29 ] 开关式的DCDC转换器，由于采用了与线性降压完全不同的方式，所以在设计时需要注意很多技巧。简略来讲，开关频率的选择，电感的大小，开关器件的耐压，允许通过电流的大小，等等都是需要考虑的对象。并且相互之间的关系也比较复杂。在此不能详细为您解释，可参考一些电源类设计的书籍。
[ 问题 30 ] 飞思卡尔MC34712/3/6/7器件共计能提供几种电压？ 电压值分别是多少？
[ 答案 30 ] 无限多个电压，输出电压是由外部的电阻值来调，想要多少电压，只要去调电阻值即可。
[ 问题 31 ] 飞思卡尔的DDR电源抗干扰性能有什么优势？
[ 答案 31 ] Compare with other solution, this product has output voltage accuracy of +/-1% accuracy and wide input voltage range for 抗干扰.
[ 问题 32 ] 飞思卡尔的MC34712/3/6/7系列器件采用何种技术提高效率降低功耗？
[ 答案 32 ] It is maily due to our product design in SMARTMOS technology and circuit design.
[ 问题 33 ] 关于DC-DC转换器在技术方面今后的发展方向？
[ 答案 33 ] The ultimate aim is to provide for high performance at lower costs. We will continue to develop higher performance power conversion devices and good regulations at higher loading and for broad range of voltages at competitive costs.
[ 问题 34 ] 贵方的产品有断电保护措施吗？
[ 答案 34 ] 有 Over current protection
Over voltage protection
UVLO
And thermal shutdown
其一个 Active Low standby and shutdown input
[ 问题 35 ] 能不能介绍一下MC3712的Vref能精确跟踪VDDQ 的基本原理？
[ 答案 35 ] It use a feedback loop topology and you can see the details from the simplified internal block diagram in the datasheet.
[ 问题 36 ] 能否简要介绍一下贵公司的SMARTMOS技术？
[ 答案 36 ] Smartmos is a proprietary fabrication process of Freescale that is able to produce the most dense, low voltage/or high voltage, encompass for analog precision capability and high power requirements of building devices such as caps, resistors, transistors, logics etc.
[ 问题 37 ] 你们的DC-DC转换器件最高的开关频率是多少？提高的瓶颈在哪里？
[ 答案 37 ] The switching frequency has a default value of 1.0?MHz and can be programmed by connecting a resistor divider to the FREQ pin, between VDDI and GND pins (for range 200k to 1MHz). You can reference to the datasheet.
[ 问题 38 ] 请介绍MC34716的负载变动幅度瞬态响应特性。
[ 答案 38 ] 瞬态响应特性与电路的工作频率、选取电感值的大小、输出电容ESR、ESL的大小，容值大小等都有关系。MC34716采用电压反馈BUCK拓扑结构，最高工作频率为1MHz，只要在设计时充分考虑利用并联输出电容得到更小的ESR、ESL值，电压波动就可以得到很好的控制。
[ 问题 39 ] 请问，MC34716相对其它稳压器有什么优势？
[ 答案 39 ] 双组输出，体积小，效率高，所需外部组件最少。
[ 问题 40 ] 请问DDR电源和DC-DC转换器的重要指标分别是什么？
[ 答案 40 ] The major difference is that DDR and DC-Dc power is that the former needs to do sinking as well as sourcing of current.
DDR memory has a push-pull output buffer, while the input receiver is a differential stage requiring a reference bias midpoint, VREF. Therefore, it requires an input voltage termination capable of sourcing as well as sinking current.
Our device can sink & source 3A, while for sourcing only can cater for 5A.
Also there are a bunch of other things like voltage tracking but this would be additional features for powering DDR memories.
[ 问题 41 ] 请问MC34712，MC34713，MC34716，MC34717DCDC产品的PSRR值怎么样？
[ 答案 41 ] PSRR值指的是电源噪声抑制比，是电路对于电源上噪声的敏感程度。对于我们的开关电源DCDC产品来讲，由于电源本身的拓扑和控制特性，电源本身会适应不同的输入电压以达到相同的输出电压。一般在DC-DC转换器中，我们不用PSRR来衡量一个电路抑制电源噪声的能力。
[ 问题 42 ] 请问MC34716芯片通过哪些方式缩减PCB的布局空间？
[ 答案 42 ] MC34716集成了同步buck电路的两个MOS管到芯片的内部，极大的节省了外围空间；而且较高的开关频率使您可以使用小尺寸电感电容，同时又能达到很高的效率，是市场上非常有竞争力优势的DDR电源产品。
[ 问题 43 ] 请问贵公司的DDR Power最多可以驱动几块存储芯片？
[ 答案 43 ] outpur =3A VTT 一般都很小， 所以可供給 1GB 的vTT current。
[ 问题 44 ] 请问上述的几个IC都是兼容DDR1/2/3标准的吗，也就是说，可以用在不同电压范围，需要设定吗，还是根据IC供电自适应的？
[ 答案 44 ] All our specified DDR power devices can work with DDRI – II – III standards. The output voltage is defined by external resistors but the Vttt output is determined by the VDDQ.
[ 问题 45 ] 请问专家，能否详细介绍VTT 电源和端电阻在存储器控制器中的作用？
[ 答案 45 ] VTT电源提供1/2的VDDQ电压，DDR存储器的推挽式输出使得电平高状态时，电流从VDDQ流向VTT，低电平状态时，电流从VTT流向GND。所以VTT电源既要提供电流也要吸收电流。端电阻起到终端匹配的作用。
[ 问题 46 ] 如果在设计时选用飞思卡尔产品，贵公司都提供哪些类型的技术支持？
[ 答案 46 ] 提供 reference desige circuit, gaber file, reference layout guide, and technical support
[ 问题 47 ] 软启动会造成时延吗？
[ 答案 47 ] Yes, that is the purpose of soft-start.
[ 问题 48 ] 软启动是什么概念？
[ 答案 48 ] Soft start is used to prevent the output voltage from overshooting during startup. Sometimes a cold start from a low level to a high level will generate a lot of transients or spikes that can harm your system. For our device we habe soft start to prevent against this. At initial startup, the output capacitor is at zero volts; VOUT = 0 V. Therefore, the voltage across the inductor will be PVIN during the capacitor charge phase which will create a very sharp di/dt ramp. Allowing the inductor current to rise too high can result in a large difference between the charging current and the actual load current that can result in an undesired voltage spike once the capacitor is fully charged. The soft start is active each time the IC goes out of standby or shutdown mode, power is recycled, or after a fault retry.
[ 问题 49 ] 什么是DDR电源？这种新的电源和直流转换与其他的电路设计方面有哪些优点？
[ 答案 49 ] DDR电源 means the power supply solution specific design for support DDR memory. Please see detail from the web material.
[ 问题 50 ] 在DC-DC 转换器的设计中，如何来提高转换效率？
[ 答案 50 ] DCDC开关转换的效率，主要影响因素有，电路开关频率，开关器件的开关速度、导通电阻，电感的DCR直流等效电阻，电容ESR消耗的功率等等。Freescale采用了较理想的工作频率范围，配合内置45mohm的MOSFET及小封装的电感，可以实现高于95%的效率。
[ 问题 51 ] 在PCB LAYOUT方面，对于DDR电源有什么要求？
[ 答案 51 ] 由于飞思卡尔的DDR电源已经集成了MOSFET，所以外围功率器件仅需电感及电容。只要是电感电容及芯片尽量靠近在一起，那么电路的电磁干扰和损耗就能尽量降低。
[ 问题 52 ] 在进行PCB LAYOUT的时候，电源的滤波如何处理？有无相关的文档介绍？
[ 答案 52 ] 电源滤波主要通过输出电容来实现，从PCB LAYOUT角度来说，输出电容需要尽量靠近电感。 您可以访问飞思卡尔的中文网站获取更多的信息 http://www.freescale.com.cn/products/powermanagement.asp，也可以通过在网站submit你的request来提问。http://www.freescale.com.cn/info/tic_home.asp
[ 问题 53 ] 在众多DC/DC产品中，用户在选择时应按什么原则？是转换效率还是其他的什么因素。
[ 答案 53 ] Effeciency is one of the consideration, other is accuracy, wide input range, physical size and easy for application.
[ 问题 54 ] 怎样在设计时减少DC/DC输出电压的纹波？
[ 答案 54 ] 您可以通过适当增加电感的感值，或者增加输出电容来减小输出电压纹波。同时，较高的开关频率也可以降低纹波。
[ 问题 55 ] 专家你好，请问对于极低电压的直流变换，贵公司有何处理办法？功率能达到多少？
[ 答案 55 ] 极低电压是多低？若一般 5V--1.8V，1.25V，等。电流大一点的话用Switching IC，功效还要看你的电流多大及外部组件，一般Portable device功率都要求90%才好。
[ 问题 56 ] 最新的DDR SRAM的存储速度是多少？
[ 答案 56 ] For DDR3-1600, the rated clock is 1600 MHz and Maximum Transfer Rate is 12,800 MB/s. Please refer to the webcast presentation.
[ 问题 57 ] DC/DC转换器的噪声有多种定义如uVrms， V/rtHz，还有dBc/Hz，它们有什么不同？那种最能反映转换器的噪音性能？
[ 答案 57 ] DCDC一般采用纹波大小来度量输出噪声。
[ 问题 58 ] MC34716单芯片方案跟MC34713加MC34712的双芯片方案，哪个效果更好，价格更低?
[ 答案 58 ] 若你需要两组电源且电流较大 (如>1.5A) 使用34716 较好，可节省空间，整体价格也较低。
[ 问题 59 ] DC/DC电源工作状态不稳定引起的电磁干扰解决措施？
[ 答案 59 ] DCDC电源工作不稳定，除了会产生EMI干扰以外，还会对整个开关电源的输出特性产生较大的影响，甚至导致电路元件的损坏。任何由于电路不稳定造成的问题，首先应当从解决稳定性下手。
[ 问题 60 ] DDR2拥有两倍于DDR的预读取系统命令数据的能力，那么它的延迟时间是否也要比DDR的大呢? 比如DDR400和DDR2-400比较。
[ 答案 60 ] This is mostly to do with the start-up time specification of DDR. It is not relevant to this topic. You can find the information in JESD79-2C (DDR2 specification) and JESD79E (DDR specification).
[ 问题 61 ] DDR标准的要求是什么？其在数据速率方面的基本原理是什么？从哪些方面提高数据速率？
[ 答案 61 ] Please refer to the web material or reference to the Double Data Rate (DDR) SDRAM Specification JESD79E
[ 问题 62 ] DDR存储器在电压精度和波纹系数上对电源的要求是什么？
[ 答案 62 ] The 2.5-V VDDQ required for the DDR logic has a tolerance of +200 mV. To maintain noise margins, VTT must track VDDQ. It has to equal VDDQ/2, or approximately 1.25 V, with an accuracy of ±3%. Finally, VREF must equal VTT to +40 mV.
[ 问题 63 ] DDR电源具体供电情况如何？属于无源技术吗？
[ 答案 63 ] 飞思卡尔DDR电源采用同步降压技术，具有很高的效率。属于有源控制。
[ 问题 64 ] DDR稳压器在降低成本方面有哪些优势？
[ 答案 64 ] 此DDR稳压器已将所有保护电路包在芯片内，不需在外加所以在成本上也较低。
[ 问题 65 ] 飞思卡尔的DDR电源，在EMC测试中的表现如何？
[ 答案 65 ] This is specific to your system, not just the device itself. For our own device, we do have tests data but only for our internal quality concerns.
[ 问题 66 ] I need complete Documentation on Routing of SDRAM, DDRSDRAM, DDR2SDRA. What is difference when moving to DDR From SDRAM routing?
[ 答案 66 ] Our device is specific to the power supply of current and voltage to the memory and not the imigration of one type of memory to the other and thus we do not provide such information.
[ 问题 67 ] I use a DSP at 200MHz of clock. Can I use faster DDR2 memory IC like 800MHz, for example, and run it at 200MHz?
[ 答案 67 ] This does not fall within the scope of our topic. But out of interests, you could but you must trace your routing and parasitics s these could violate your setup & hold times.
[ 问题 68 ] I would like to know what problems can I have with the power supply for my DDR2 memory?
[ 答案 68 ] If your DDR power supply is not properly configured, your system could suffer from squence slipper and lose of data.
[ 问题 69 ] Layout时，与DDR2/3的placement及走线有需要注意的地方吗？
[ 答案 69 ] Place the inductor near to the chip for reduce switching noise and use smaller layout place. Please refer the layout giude on web.
[ 问题 70 ] MC34712/3/6/7的主要区别在哪里？
[ 答案 70 ] MC34712 / 716 是用做DDR稳压用它们有Sink & source 的功能 MC34713/717 是DC/DC的转换器。
[ 问题 71 ] MC34712的电源只能是5V？能否用3.3V？
[ 答案 71 ] 可以的操作范围 : Vin=3.0~6.0V， Vout=0.7~3.6V
[ 问题 72 ] MC34712与MC34716可编程切换频率的实现方式，如何切换的？
[ 答案 72 ] The switching frequency is defaulted at 1MHz. You can set this frequency by an external resistor connected to FREQ pin. Pls see our datasheet for more details.
[ 问题 73 ] MC34716， MC34717DCDC产品的PSRR值怎么样？
[ 答案 73 ] DCDC电源没有PSRR的概念，输出电压始终稳压于固定值。
[ 问题 74 ] MC34716本身功耗多少，DC－DC转换电压一般多少？
[ 答案 74 ] This depend on the load of your board and can be up to 95%.
[ 问题 75 ] MC34716是如何工作的？它在什么样的环境下工作？
[ 答案 75 ] MC34716采用同步降压DCDC技术。输入工作电压范围为3V至6V。
[ 问题 76 ] MC34716适应电压波动范围是多少？
[ 答案 76 ] MC34716的工作电压范围是3V到6V。
[ 问题 77 ] MC34716相对其它稳压器有什么优势？
[ 答案 77 ] MC34712 / 716 是用做DDR VTT 稳压用它们有Sink & source 的功能。其优势为高度整合 (MOSFET inside) 空间体积小效率高使用方便等。
[ 问题 78 ] MC34716在什么样的环境下工作？
[ 答案 78 ] Operating at 3.0 V ≤ VIN ≤ 6.0 V， -40°C ≤ TA ≤ 85°C， GND = 0 V. Please refer to data sheet.
[ 问题 79 ] MC34716作为电源管理IC，他的切换时间是多少？
[ 答案 79 ] The Switching Frequency Range can be programmable from 200 kHz to 1Mhz.
[ 问题 80 ] Noise性能？ripple有多大？
[ 答案 80 ] 1.0 MHz with a default of 1.0 MHz.
[ 问题 81 ] SMARTMOS？技术是飞思卡尔半导体公司独有的吗？
[ 答案 81 ] Yes it is, but it does not mean that we won't help certain customers to fabricate their devices using our process.
[ 问题 82 ] Vref voltage not stable working in vref voltage, this verf will be have any impact in DDR, DDR2, DDr3?
[ 答案 82 ] If Vref voltage is not stable work in ref range, there will be time shifting for the data. Please reference to the web material.
[ 问题 83 ] VTT与其他品牌有什么区别？
[ 答案 83 ] VTT 是DDR Bus Termination 的电压一般DDR都会需要供给这电源。
[ 问题 84 ] 单双路的区别是什么？
[ 答案 84 ] There are only one output voltage at single channel one. Mostly the application will be generic DC-DC converter. For dual channel, there are two channel output, one for VTT and one for VREF. It is applied in DDR memory power system.
[ 问题 85 ] 当负载短路负载电流过大时，如何保护的？
[ 答案 85 ] These devices have Over Current Limit and Short Circuit Protection circuitry. Pls see our datasheet for more details.
[ 问题 86 ] 低压降（LDO）线性稳压控制电路也是集成在电源管理IC器件里面吗？
[ 答案 86 ] 本系列的电源管理器件并没有包含LDO。VREF的输出是跟踪1/2的VDDQ电压。
[ 问题 87 ] 对于MC34712，是否可以在VREFIN上输入一个频率不是太高的信号，在VTT得到大电流的输出，即做一个类似跟随器的功放？
[ 答案 87 ] 理论上是可行的。很有创意的想法。
[ 问题 88 ] 对于极低电压的直流变换，贵公司有何处理办法？功率能达到多少？
[ 答案 88 ] For light loading, it is a challenge to maintain high efficiency as this is the inherent nature of switching losses from the internal power FETs. To overcome this, one would have to incorporate pulse skipping techniques within the device. However, we do not have this as most of the time, the FETs are in their saturation mode and thus operating in the high efficiency region.
[ 问题 89 ] 飞思卡尔MC34712/3/6/7器件的优势和特性表现在哪些方面？其兼容性如何？
[ 答案 89 ] 其优势为高度整合 (MOSFET inside) 空间体积小效率高使用方便等。
[ 问题 90 ] 飞思卡尔MC34712或MC34716系列主要应用在什么方面？和其他厂家产品相比，明显的优势是什么？
[ 答案 90 ] MC34712 / 716 是用做DDR VTT 稳压用它们有Sink & source 的功能。其优势为高度整合 (MOSFET inside) 空间体积小效率高使用方便等。
[ 问题 91 ] 飞思卡尔最新DDR电源和DC-DC转换器最大电流能够达到多少？
[ 答案 91 ] Our device can provide upto 3A output for sink and source operation, while for only sourcing current, it can sustain upto 5A.
[ 问题 92 ] 高度集成的器件本身发热大吗？怎么处理？
[ 答案 92 ] 高集成度并不意味着发热。发热是由于电路工作过程中，电流流过导通电阻，及开关管不停的开关工作，产生功耗而变成热量。飞思卡尔的器件采用了同步高效率的开关方式，且封装散热良好，因此能够很好的控制发热量。
[ 问题 93 ] 贵公司的技术支持电话是多少？
[ 答案 93 ] Pls visit our website www.freescale.com.cn, as contacts would depend on your region of residence.
[ 问题 94 ] 贵公司在河南有经销商吗？
[ 答案 94 ] Pls visit our website www.freescale.com.cn, as contacts would depend on your region of residence. We would have our distributors to help you if we are unable to reach you.
[ 问题 95 ] 今天介绍的这几款产品相比同类产品价格有优势吗？
[ 答案 95 ] 它们是高度整合，整体上价格较便宜。
[ 问题 96 ] 据我所知DDR2内存上仍然只有一个DRAM核心，但是它可以并行存取，在每次存取中处理4个数据而不是两个数据。是因为这个原因，所以传输速率提高了一倍么？是否还有其它的技术上的关键环节？
[ 答案 96 ] This is the essence of double data rate and what you have described is exactly this.
[ 问题 97 ] 目前高端的计算设备通常都是采用飞思卡尔产品吗？
[ 答案 97 ] Yes, we are target for this market.
[ 问题 98 ] 切换频率最大的范围是多大？
[ 答案 98 ] The max switching frequency is 1MHz.
[ 问题 99 ] 请介绍该电源的性价比优势。
[ 答案 99 ] Pls refer to the webcast for page that's entitled Freescale benefits. Our devices basically are small pkg size, high switching frequency and efficiency, integrated FETS etc.
[ 问题 100 ] 请问：MC34716，产品的PSRR值？
[ 答案 100 ] DCDC产品产生稳定输出电压，无PSRR值概念。
[ 问题 101 ] 请问：网上有相关的设计例程吗？
[ 答案 101 ] Yes, pls see our freescale site and look for application notes.
[ 问题 102 ] 请问：有中文版的技术资料吗？
[ 答案 102 ] Currently we do not have, but will do so in the near future.
[ 问题 103 ] 请问：与其他厂家类似产品相比，贵方产品有什么特点？
[ 答案 103 ] 其特势为高度整合 (MOSFET inside) 空间体积小效率高使用方便等。
[ 问题 104 ] 请问：在哪里有更多的关于贵公司产品的免费在线课程？
[ 答案 104 ] 我们会举办免费课程会通知大家，你也可以到网站上看看 www.freescale.com。
[ 问题 105 ] 请问：MC34712/13/16/17的PSRR值怎么样？
[ 答案 105 ] DCDC产品产生稳定输出电压，无PSRR值概念。
[ 问题 106 ] 请问：MC34712/6系列DDR存储器是多大的，具有多少M容量？
[ 答案 106 ] The MC34712/6 is power management IC for the DDR system only but not DDR memory.
[ 问题 107 ] 请问：MC34716的DC－DC转换电源效率多高有哪几种功能？
[ 答案 107 ] This depend on the load of your board and can be up to 95%.
[ 问题 108 ] 请问：该电源与以往的电源最大的不同之处在哪里？对广大的消费者来说，这款电源最大的优点是什么？
[ 答案 108 ] 其优势为高度整合 (MOSFET inside) 空间体积小效率高使用方便等。
[ 问题 109 ] 请问：贵公司的芯片是否是可编程的，用什么编程方式？
[ 答案 109 ] It depends on what feature you are asking for. For instance, for the switching freq, the switching frequency is defaulted at 1MHz. You can set this frequency by an external resistor connected to FREQ pin. Pls see our datasheet for more details.
[ 问题 110 ] 请问：能提供1.2v DC－DC器件吗？
[ 答案 110 ] These devices can provide for such voltage outputs, they can be used as generic DC-DC converters.
[ 问题 111 ] 请问：你们DCDC电源转换采用的是什么结构啊？是电压型PWM控制原理吗？
[ 答案 111 ] 飞思卡尔电源采用电压反馈型PWM控制，同时使用同步整流提高效率。
[ 问题 112 ] 请问：上述所谓的软启动是什么概念，请详细说明。
[ 答案 112 ] 电路刚开始工作时，由于输出电容上并没有积蓄能量，因此电压很低，电路的反馈回路检测到低电压值时，将会采用最宽的PWM来尽快使输出电压上升，但是此过程由于反馈回路反应很快，因此容易造成电流过大，损坏电路元件。使用软启动是将输出电压上升的速度减慢，从而启动电流得到控制。
[ 问题 113 ] 请问一下，MC34716相对其它稳压器有什么优势？
[ 答案 113 ] MC34712/716 是用做DDR VTT 稳压用，它们有Sink & source 的功能，其优势为高度整合 (MOSFET inside) 空间体积小效率高使用方便等。
[ 问题 114 ] 请问：有电源管理方面的芯片吗？
[ 答案 114 ] Yes we have many. Pls visit our website to search for the application needs of your Power Management IC.
[ 问题 115 ] 请问：与DDR控制器相比有优势吗？
[ 答案 115 ] MC34712/716 是用做DDR VTT 稳压用，它们有Sink & source 的功能，其优势为高度整合 (MOSFET inside) 空间体积小效率高使用方便等。
[ 问题 116 ] 如何保证主板上的终结电阻与内存模组的匹配？
[ 答案 116 ] The MC34712 supplies the VTT and a buffered VREF output. To ensure compliance with DDR specifications, the VDDQ line is applied to the VREFIN terminal and divided by 2 internally through a precision resistor divider. This internal voltage is then used as the reference voltage for the VTT output. The same internal voltage is also buffered to give the VREF.
[ 问题 117 ] 如何计算MC34716芯片的实际温度？
[ 答案 117 ] 计算芯片内部两个开关管的功率损耗，再乘以芯片的热阻，就可以得到芯片在一定环境温度下的温升。
[ 问题 118 ] 软起动的工作原理及作用。
[ 答案 118 ] 电路刚开始工作时，由于输出电容上并没有积蓄能量，因此电压很低，电路的反馈回路检测到低电压值时，将会采用最宽的PWM来尽快使输出电压上升，但是此过程由于反馈回路反应很快，因此容易造成电流过大，损坏电路元件。使用软启动是将输出电压上升的速度减慢，从而启动电流得到控制。
[ 问题 119 ] 实际应用中，为确保系统的稳定开关频率最高不能超过多少？
[ 答案 119 ] The max switching frequency is 1MHz.
[ 问题 120 ] 通常的DC-DC都包含BUCK和BOOST两种类型，但它们都存在一些缺点，你们对升压和降压型DC-DC做了哪些改善，它们有什么突出的特点？
[ 答案 120 ] 升降压电路的特性是由电路本身采用的拓扑结构所决定的。所谓优缺点要看您应用的要求。如果效率是您考虑的主要因素，那么飞思卡尔采用的同步整流方式可以极大的提高低电压大电流情况下的电路效率。
[ 问题 121 ] 网络上有无相关SMARTMOS？技术文档参考？
[ 答案 121 ] This is our proprietary technlogy. However, you should be able to find related information about what our process technology has to offer. Pls visit our website for this or consult with your regional support group.
[ 问题 122 ] 网络上有相关的设计软件下载吗？
[ 答案 122 ] I am not sure what you are asking here but we do have evaluation boards and tools to help you accomplish your designs using our devices.
[ 问题 123 ] 我知道飞思卡尔的电源管理IC性能非常不错，它集regulator和音频管理于一体，在手机和mp4上非常受欢迎。请问你讲的DC-DC仅仅是REGULATOR吗？
具体的尺寸如何，能给一些在design上的建议吗？thanks
[ 答案 123 ] Yes these are switching regulators, our package size is 4x4mm2, 24pin QFN. Pls download our application notes for design hints.
[ 问题 124 ] 相关技术资料有中文资料可以下载吗？
[ 答案 124 ] Currently we do not have, but will do so in the near future.
[ 问题 125 ] 想知道MC34712与MC34716的正常工作的上电时序。
[ 答案 125 ] Our device allows the output of the MC34712 to track 1/2 the voltage applied at the VREFIN pin. This allows the VREF and VTT voltages to track 1/2 VDDQ and assures that none of them will be higher than VDDQ at any point during normal operating conditions. For power down during a shutdown (S5) mode, the MC34712 uses internal discharge MOSFETs (M5 and M6 on Figure 2) to discharge VTT and VREF respectively. These discharge MOSFETs are only active during shutdown mode. Using this block along with controlling the SD and STBY pins can offer the user power sequencing capabilities by controlling when to turn the MC34712 outputs on or off.
[ 问题 126 ] 用不同品牌的SDRAM兼容吗？需要注意什么问题？
[ 答案 126 ] As long as the SDRAM is work within the JEDEC Standard requirement, the MC34712/6 series product can operate with that.
[ 问题 127 ] 有DEMO Board提供测试验证吗？
[ 答案 127 ] Yes, pls consult with your local Freescale support group.
[ 问题 128 ] 有没有用适用于手机设计的1.8V或1.2v DC－DC器件，请简单介绍一下相对于LDO的优势。
[ 答案 128 ] 我们将推出一系列的手机用DC/DC。与LDO相比，其优势为效率高省电及更多的保护功能等。
[ 问题 129 ] 在DC-DC 转换器的设计中, 电感参数如何来确定？
[ 答案 129 ] 首先，需要知道您想要的工作频率；其次，你预想中的电流纹波及开关管所能承受的最大电流和电感的磁饱和电流；还有就是对DCR的要求，封装的要求及尺寸、高度的要求。
[ 问题 130 ] 在EMC方面有什么措施吗？
[ 答案 130 ] 飞思卡尔电源采用芯片级的集成技术，已将同步整流所需要的MOS管集成至芯片内部，从而避免了MOS外置时layout上可能产生的干扰问题。
[ 问题 131 ] 在高频下，为什么电感电阻值可以选用小的？
[ 答案 131 ] 我相信您是指电感值。感值和频率同时影响开关电源电感上的电流纹波大小，而电流纹波是输出电压纹波的重要参考量。在提升频率的同时，由于减少了电感电流在外部压差作用下电流上升或下降的时间，因此电感电流的纹波得到控制。也就是说，感值和频率在一定程度上是反比的关系。
[ 问题 132 ] 作为面向DDR1/2/3产品的MC34712与MC34716具有哪些特性？
[ 答案 132 ] The MC34712/6 product series is design for working with DDR1/2/3 product. Please refer to the web material and the datasheet of the product for it's feature.
[ 问题 133 ] Layout时，与DDR2/3的placement及走线有需要注意的地方吗？
[ 答案 133 ] The signal/data line should be as short as possible. Also the placement of the switching inductor should place as close as to the IC as possible. Details please refer to our layout guideline on web.
[ 问题 134 ] DDR稳压器在降低成本方面有哪些优势。
[ 答案 134] By using MC34712/6 series product, no external MOSFET need and the PCB place need for the layout is small. High switching frequecny (1Mhz), smaller inductor and capacitor need. All of them can lower the system cost.
[ 问题 135 ] DDR存储器在电压精度和波纹系数上对电源的要求是什么？
[ 答案 135 ] 请参考JEDEC发布的DDR内存标准。