飞思卡尔^TM最新DDR电源和DC-DC转换器Freescale

简介：本次在线座谈将就飞思卡尔^TM最新增加的电源管理器件、MC34712/6系列DDR存储器和通用DC-DC转换器展开讨论。MC34712或MC34716系列是一系列高度集成、高效率而又小巧的器件，可用于DDR供电或通用DC-DC转换。

本次研讨会首先将介绍DDR存储器电气特性和数据速率方面的基本原理，然后将讨论DDR标准的要求。接下来，我们会介绍飞思卡尔器件：4款专用IC的优势和特性。演讲环节以这些器件的使用和适用性实例作结。

问：端电阻怎么计算，还是有一个固定的值
答： Termination resistance depend on the sink and source current need for the memory system. You can reference the DDR system level diagram in our datasheet.

问：EMI问题怎么考虑?提供参考PCB设计吗？
答： 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。Freescale提供demo板供客户参考，具体可联系销售部或代理商。

问：如何计算MC34716芯片的实际温度?
答： 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 th

问：mc34712系列在抗过压和噪声及热保护上有哪些优势？
答： 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

问：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： 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：软启动是什么概念
答： 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 a

问：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： 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：怎么可以得到DEMO板
答： Contact Freescale sales in your region.

问：Freescale 那些产品具有VREF输出?幅度是多高?输出精度呢?
答： MC34712 and MC34716 have VREF output. The accuracy is 1%.

问：最新的DDR SRAM的存储速度是多少？
答： For DDR3-1600, the rated clock is 1600 MHz and Maximum Transfer Rate is 12,800 MB/s. You can reference to the Web material.