Silicon MEMS (Micro-electro-mechanical systems) oscillators are increasingly becoming the timing solution of choice for designers wishing for their applications to meet higher quality standards. This goes beyond increased timing accuracy to developing products that don't wear out as early, can handle a wider variety of operating conditions, have a longer battery life, and are smaller in size. Thus far, SiTime is the leader in silicon-based timing solutions, commanding a 90% market share and having shipped well over a billion units.
由于设计和施工,MEMS科裕tors are inherently superior to traditional quartz crystal resonators. Beginning with a more standardized and less complicated manufacturing process, MEMS oscillators are introduced to fewer opportunities for contamination. This results in a 30 times better DPPM (defective parts per million) and MTBF (mean time between failures), i.e. better quality and reliability. They are also far more robust in the face of most environmental conditions. Because MEMS oscillators have no exposed PCB connections between the resonator and oscillator circuit, and because the oscillator circuits are optimized for electrically noisy conditions, they are much less sensitive to EMI (electro-magnetic interference). Also, because their mass is thousands of times less than that of quartz resonators, they are far less sensitive to shock and vibration. Similar design features make them less sensitive to operating temperature and board noise.
利用石英谐振器有一种明显的益处，这是它们比MEMS振荡器更便宜。这可能是许多人忽略上面描述的众多好处并使用Quartz，并且当然一些应用程序根本不需要最高质量，可靠性和稳健性的组件。但是，必须一定要考虑超出零件初始成本的成本。首先，石英谐振器需要更大的工程努力，不仅在选择正确的谐振器时，而且还需要避免和克服冷启动失败，不匹配的晶体，EMI合规性能等的常见问题。另一方面，MEMS振荡器简化了系统通过“即插即用”来设计，这意味着上述问题不适用，并保证启动。第二;凭借其较小的占地面积，能够驾驶多个负载，以及它们不需要负载电容器的事实;MEMS振荡器利用显着较少的板空间，并且可以具有较小的整体BOM（材料清单）成本。最后，Sentime MEMS振荡器是可编程的，使它们更具可用，使工程师能够更加灵活，以实现更快的市场时间。
A complete timing solution, SiTime oscillators couple a MEMS resonator and a programmable CMOS IC (which includes the oscillating circuit, PLL (phase-locked loop), temperature compensation, voltage regulators, and filters) in the same package. In contrast to quartz resonators, where different parts must be manufactured to attain different resonating frequencies, MEMS oscillators are made by manufacturing batches of field-programmable, or "blank", oscillators and then programming them with different configurations to produce different output frequencies. Many other parameters are configurable in addition to frequency, including supply voltage, frequency stability, output drive strength (i.e., rise/fall time), etc. SiTime produces several series of oscillators which cover every oscillator type (e.g.,XO.,TCXO.,VCXO,dcxo.,OCXO， 和ssxo.) and several specialized categories, such as low-power, automotive, ruggedized, etc. Currently, there are dozens of oscillator series to choose from and hundreds of blank part numbers available. From this relatively small set of blanks, billions of part numbers can be generated.
As an example, consider the blank part number SIT2001BI-S1-XXX-000.FP000, which is theSIT2001.标准系列SOT23振荡器在工业温度范围内。本系列的部件号崩溃如下图1.请注意，频率可以选择1 MHz至110 MHz的范围，具有六个小数的准确度！这意味着109,000,001总频率可以通过该单一物理部分产生。考虑到“特征引脚”的三个选项，六种“电源电压”选项，频率稳定的三个选项，以及“输出驱动强度”的九种选项;可以发现有52.974billion可能源于该空白部分的可能部分编号。
图1：部件号指南取自位于SIT2001B系列截面振荡器的数据表。
These blank parts can be programmed by SiTime at the factory in production volumes with a lead time of 3 to 5 weeks. Up to this point, Digi-Key has been ordering these pre-programmed parts from SiTime and maintaining stock on the most popular oscillator configurations of each series. This is no different than the way Digi-Key treats non-programmable parts, like quartz resonators, and it works fine for customers ordering the standard oscillator configurations. However, any customer requesting a custom configuration would have to wait the 3 to 5 week lead time on an order subject to large minimum quantities. When these custom requests are made, the part numbers get added to Digi-Key's catalog but are generally not kept in stock as they are ordered so infrequently. At last count, Digi-Key had 176,509 different part numbers for SiTime oscillators listed on the website, but only 5,913 of them (a meager 3.35%) were in stock.
为了克服这些问题并开始充分利用环境振荡器的可编程性，Digi-key最近添加了一台专用于对我们仓库进行编程的自动编程机器。本机（图2）目前采用八个编程插座，能够每小时编程约1,500个单位。我们目录中的大部分数量现在可以在短短24到48小时的情况下订购，没有最低数量！Digi-Key将简单地从环境中储存空白部件，而不是从工厂预编程的空白部分，并将其编程为订购。这也意味着Digi-Key现在有效地在我们目录中的几乎所有的静脉振荡器上有库存，只排除了必须在工厂编程的一些特殊系列。换句话说，在切换到自定义编程后，Digi-key现在有超过99％的Sentime振荡器，而不是仅为3.35％。
请注意，虽然订购区间振荡器的过程没有改变，但现在必须通过定制订单环境可编程振荡器类别on Digi-Key's TechForum. Once a request is submitted, an e-mail will be immediately sent to one of our Applications Engineering Technicians who will verify the new part number and get it added to the Digi-Key website.
图2：DIGI-Key自动编程机的照片将空白振荡器放置在一个编程插座中。（图像来源：Digi-Key）
sitMEMS oscillators offer a compelling alternative to traditional timing solutions. Not only are they of higher quality, more reliable, and more robust; but their integrated and programmable design doesn't come with high engineering costs, utilizes less board space, and facilitates greater design flexibility. From a few hundred base part numbers spanning the comprehensive collection of oscillator families, billions of part numbers with unique configurations can be derived. Still, without a distributor taking full advantage of this capability, only the standard oscillator configurations will be readily available. Indeed, before dedicating an automated programming machine to SiTime oscillators, the uncommon, custom configurations could only be acquired at production quantities with considerable lead times. But now, with Digi-Key's fast shipping and custom programming capability, customers can get practically any SiTime oscillator configuration, at any quantity, in a matter of days!
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关于作者：Matt Mielke，Digi-Key
Matt Mielke于2016年赢得了他在计算机工程学士学位的计算机工程学士学位。他随后在Digi-Key Electronics加入了应用工程系，在那里他通过开发参考设计和一代来支持客户必威体育官网手机登录技术内容。他的兴趣领域包括低级嵌入式编程，低功耗设计和数字信号处理。
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