| 主题：突破比特位界限--飞思卡尔™ Flexis™系列微控制器的介绍 |
| 在线问答： |
| [主持人：ChinaECNet] |
各位听众（网友），上午好！欢迎参加中电网在线座谈。今天，我们有幸邀请到Freescale公司的专家就“飞思卡尔最新DDR电源和DC-DC转换器”举行在线座谈。在座谈中，您可就您关心的问题与Freescale公司的专家在线进行直接、实时的对话交流。中电网衷心希望通过大家的共同努力，不仅能够增进各位听众（网友）对“飞思卡尔最新DDR电源和DC-DC转换器”的了解和掌握，而且能够为大家事业的发展带来裨益。 |
[2007-8-28 10:20:11] |
| [主持人：ChinaECNet] |
我们已经进入问答阶段如果听众想重温演讲或内容可以点击下面“回顾演示”重看演讲。 |
[2007-8-28 10:25:20] |
| [问：sduboy] |
能否简要介绍一下贵公司的SMARTMOS技术? |
| [答：飞思卡尔专家] |
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. |
[2007-8-28 10:28:19] |
| [问：sduboy] |
请问MC34716芯片通过哪些方式缩减PCB的布局空间？ |
| [答：飞思卡尔专家] |
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。 |
[2007-8-28 10:28:24] |
| [主持人：ChinaECNet] |
我们已经进入问答阶段如果听众想重温演讲或内容可以点击下面“回顾演示”重看演讲。 |
[2007-8-28 10:28:59] |
| [问：fanjiali2000@yahoo.com.cn] |
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：飞思卡尔专家] |
MC34712 已提供VTT 所以它就不必再外加一組VTT電源 可節省pcb空間 |
[2007-8-28 10:30:44] |
| [问：vaudy] |
If I developp 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：飞思卡尔专家] |
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. I assume no other things are changed like voltages, placement of other blocks etc. |
[2007-8-28 10:32:04] |
| [问：birdshyyang] |
MC34716的散热情况如何，layout时是否有要注意的地方 |
| [答：飞思卡尔专家] |
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。 |
[2007-8-28 10:32:30] |
| [问：buck] |
MC34712驱动能力有多大？能同时驱动多片DDR SDRAM 吗？ |
| [答：飞思卡尔专家] |
Driving current 3A 一般VTT 電流都很小DDR 1GB 的vtt 不會超過2A 所以可支援
|
[2007-8-28 10:33:30] |
| [问：qeliyanli] |
mc34716与mc34164的主要区别是什么 |
| [答：飞思卡尔专家] |
Mc34164 is a undervoltage sensing device, and is entirely different to our DDR supply device. |
[2007-8-28 10:37:31] |
| [问：cmoswangyan] |
请问ddr电源和dc—dc转换器的重要指标分别是什么 |
| [答：飞思卡尔专家] |
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.
|
[2007-8-28 10:42:51] |
| [问：callancc] |
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：飞思卡尔专家] |
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. |
[2007-8-28 10:52:04] |
| [主持人：ChinaECNet] |
各位观众，现在用户提问很踊跃，专家正在逐一回答。请耐心等待您问题的答案，同一问题请不要多次提交。 |
[2007-8-28 10:52:27] |
| [问：sd2620] |
贵方的产品有断电保护措施吗？ |
| [答：飞思卡尔专家] |
有 Over current protection
Over voltage protection
UVLO
And thermal shutdown
其一個 Active Low standby and shutdown input |
[2007-8-28 10:56:05] |
| [问：xcsunsz] |
都支持哪些通讯接口？ |
| [答：飞思卡尔专家] |
它只是一個單純的 電源供給
所以沒有通訊接口的問題
任何需要 DDR vtt電源都可以用 |
[2007-8-28 10:58:12] |
| [问：fanjiali2000@yahoo.com.cn] |
mc34712系列在抗过压和噪声及热保护上有哪些优势？ |
| [答：飞思卡尔专家] |
I will not try to make comparisons, it is not the objective of this webcast, but these devices offer:-
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.
You need to read our datasheet to understand more. Thanks.
|
[2007-8-28 10:59:09] |
| [问：xxtaotao] |
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：飞思卡尔专家] |
提供 reference desige circuit, gaber file, reference layout guide, and technical support |
[2007-8-28 10:59:44] |
| [问：xinganliu] |
飞思卡尔的DDR电源抗干扰性能有什么优势？ |
| [答：飞思卡尔专家] |
Compare with other solution, this product has output voltage accuracy of +/-1% accuracy and wide input voltage range for 抗干扰.
|
[2007-8-28 11:00:40] |
| [问：johncooper] |
请介绍MC34716的负载变动幅度瞬态响应特性.谢谢! |
| [答：飞思卡尔专家] |
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。 |
[2007-8-28 11:00:43] |
| [问：buck] |
能不能介绍一下MC3712的Vref能精确跟踪VDDQ 的基本原理？ |
| [答：飞思卡尔专家] |
It use a feedback loop topology and you can see the details from the simplified internal block diagram in the datasheet. |
[2007-8-28 11:04:40] |
| [问：zjlicool] |
在PC中对DDR DIMM模块供电,请问专家有什么建议? |
| [答：飞思卡尔专家] |
Would you please more specify your question? |
[2007-8-28 11:06:42] |
| [问：xinganliu] |
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：飞思卡尔专家] |
It is maily due to our product design in SMARTMOS technology and circuit design. |
[2007-8-28 11:08:28] |
| [问：fanjiali2000@yahoo.com.cn] |
mc34716是如何保证电压的1％精度的？ |
| [答：飞思卡尔专家] |
The 34716 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. |
[2007-8-28 11:11:24] |
| [问：cyberxx] |
MC34712或MC34716系列器件的工作温度范围？ |
| [答：飞思卡尔专家] |
Our temp range is between -40 to 85C. |
[2007-8-28 11:14:10] |
| [问：birdshyyang] |
DDR2/3超频时，你们的建议方案 |
| [答：飞思卡尔专家] |
We don"t recommend to use the product in non-standard conditions. |
[2007-8-28 11:14:13] |
| [问：zhengfei] |
MC34712或MC34716系列器件工作稳定性都会受到哪些因素影响？ |
| [答：飞思卡尔专家] |
這兩個IC 是高品質的設計 對外部的干擾有很強的免疫力
只要 不要超過此IC 的規格規範 不會有這些問題
一般Switching IC 要注意外部的穩定度設計 如 L, C, 值
及Layout 上注意 雜訊等 |
[2007-8-28 11:15:04] |
| [问：jida_song] |
MC34716在解决电磁干扰方面采取了哪些措施 |
| [答：飞思卡尔专家] |
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。 |
[2007-8-28 11:16:08] |
| [问：birdshyyang] |
如何计算MC34716芯片的实际温度? |
| [答：飞思卡尔专家] |
There are many techniques, one would have an opposite temp coeff closed loop circuit to do this. The opposire temp coeff will counteract with the change of the thermal of the monitoring device. I cannot tell you anymore but our device has the thermal protection block that can do this. Each channel has its own thermal shutdown block. Thermal limit detection block monitors the temperature of the device and protects against excessive heating. If the temperature reaches the thermal shutdown threshold (TSDFET), the converter output switches off and the power good output signal indicates a fault by pulling high. The device will stay in this state until the temperature has decreased by the hysteresis value and then After a time-out period (TTIMEOUT) of 100 ms, the device will retry automatically and the output will go through a soft start cycle. If successful normal operation is regained, the power good output signal is asserted low to indicate that. |
[2007-8-28 11:19:08] |
| [问：howaabb] |
MC34716有那些节电模式和保护功能? |
| [答：飞思卡尔专家] |
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.
You need to read our datasheet to understand more. Thanks.
|
[2007-8-28 11:22:49] |
| [问：taneliu] |
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：飞思卡尔专家] |
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freescale的中文网站获取更多的信息，也可以通过在网站submit你的request来提问。 |
[2007-8-28 11:24:24] |
| [问：zhengfei] |
MC34712或MC34716系列器件性能受温度影响大吗？ |
| [答：飞思卡尔专家] |
Operation temperature is -40~85 C degree.
只要此範圍在 幾乎不受溫度影響 |
[2007-8-28 11:26:02] |
| [问：dy200101] |
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?谢谢回复! |
| [答：飞思卡尔专家] |
DDR电源 means the power supply solution specific design for support DDR memory. You can see detail from the web material.
|
[2007-8-28 11:26:32] |
| [问：hbm007] |
软启动是什么概念 |
| [答：飞思卡尔专家] |
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. |
[2007-8-28 11:28:37] |
| [问：wzjjw] |
DDR存储 |
