让我们面对这个一现实：大多数时候我们的移动设备都是闲置的。无论你多么沉迷于在移动设备上检查消息、浏览网络、听音乐还是玩游戏，它大部份的时间都还是 等着你去启动。然而，在这一段闲置期间，你的设备其实并未完全关闭。例如，如果蓝牙功能开启，它每隔几秒钟就必须唤醒，以确定是否有配对设备想传输数据。 同样地，它还必须定期检查按钮的点选、无线网络活动，以及进行电池监控功能。
根据SiTime公司表示，其全新的高精度实时频率(RTC)可在这些作业期间节省50%或更多的电源，并使电池的使用寿命增加至少一倍。
SiTimes高精确TCXO为传感器、蓝牙与Wi-Fi等实现更小取样窗口，从而有助于延长可穿戴式设备的电池寿命。
Source：SiTime公司nV9esmc
SiTime公司执行副总裁Piyush Sevalia表示，“透过采用全新的 SiT1552 MEMS 32kHz TCXO (温度补偿振荡器)实时频率，对于内建大电池的设备而言，所节省的功率或许不算太多，但对于搭载小型电池的物联网(IoT)和可穿戴式设备来说，却可大幅扩展使用寿命。”
每 一款移动设备都有一个32kHz的 RTC 来记录时间，告诉该设备何时该唤醒以及何时履行其职责。大多数的 RTC 都具有100-250PPM的精确度，这已足以使该设备免于反应迟滞或延迟了。然而，对于像蓝牙配件等实时设备，即使是达到20PPM都意味着该软件设计 者必须包括缓冲时间，才能确保外部设备在数据传送以前正确连接。
基本上，这表示软件设计者在唤醒作业开始时增加更多时间，以 确保两个设备之间的通讯顺利进行，然后在作业结束设备回到闲置模式以前增加更多时间，以确保所有的资都完成传输作业。然而，透过 SiTimes SiT1552 TCXO RTC ，其准确度达业界最低的5PPM，可让软件编写人员大幅缩短缓冲时间，从而节省功率以及延长电池寿命，特别是可穿戴设备。
“当我们开始与客户讨论我们的实时频率TCXO版本时，并没意识到这个问题，但他们立即告诉我们一款高精度的 RTC 能够多么显著地延长电池寿命——尤其是可穿戴设备，”Sevalia表示。
SiTimes以温度控制的MEMS振荡器(TCXO)采用独特的3D芯片堆栈，其125微米厚的微型MEMS芯片以覆晶安装在内含电子组件的ASIC底部焊点之间。
Source：SiTime公司nV9esmc
该SiT1552 TCXO 采用与其于去年发表的 SiT15xx (20-100PPM)所用的相同 TempFlat 技术。透过增加芯片上温度传感器以及一款“模拟温度—数字转换器”(ADC)，SiTime能够提高精确度至±5PPM。该 SiT1552 TCXO 采用1.5×0.8×0.55mm的芯片级封装(CSP)，大约是石英晶体的六分之一大小，据称是目前最小的实时频率，且其功耗还不到1微安(uA)。该 MEMS 芯片即小且薄(厚度仅400×400×125微米)，使其适于内含电子组件的ASIC底部焊球之间。
该 SiT1552 也瞄准需要长期精确度的设备制造商，例如智能仪表领域等设备需要保持20年或以上的精确度。该组件具有500亿小时的使用寿命以及涵盖 SiTime 的终身保固。 SiT1552 现已量产。从SiTime于2005年成立以来，至今已出货2.2亿颗频率芯片。
本文授权编译自EE Times，版权所有，谢绝转载
编译：Susan Hong
参考英文原文：MEMS Clock Cuts Wearable Power in Half，by R. Colin Johnson
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MEMS Clock Cuts Wearable Power in Half
R. Colin Johnson
PORTLAND, Ore. — Let's face it: Most of the time our mobile devices are idle. No matter how addicted you've become to checking for messages, surfing the web, listening to music, or playing games, most of the time it's waiting for you to activate it. However, during this idle time your unit is not totally off. If Bluetooth is turned on, for instance, it has to wake up every few seconds to make sure no paired device is wishing to transfer data. Likewise, it has to periodically check for button clicks, WiFi activity, and for battery supervision functions.
During those operations SiTime Corp. of Sunnyvale, Calif., claims its new, high-precision, real-time clock can save 50 percent or more of the power usually expended during idle time, at least doubling the battery life during those periods.
SiTimes super-accurate temperature compensated MEMS oscillator (TCXO) helps extend battery life of wearables by allowing smaller sampling windows for sensors, Bluetooth, WiFi, et. al.
(Source: SiTime)
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"These power savings might not amount to much for a device with a big battery, but for Internet of Things and wearable devices with tiny batteries, their lifetime can be significantly extended with our new SiT1552 MEMS 32 kHz TCXO [Temperature Compensated Oscillator] real-time clock," Piyush Sevalia, executive vice president of marketing, told EE Times.
Every mobile device has a 32 kHz real-time clock to keep track of time, telling its device when to wake up and perform its duties. Most of these real-time clocks have a precision of 100 to 250 parts per million (PPM), which is adequate to keep a device from seeming unresponsive or sluggish. However, for real-time devices like Bluetooth accessories, even 20 PPM means that the software designers have to include buffer time to make sure the external device is connected properly before data is transferred.
In essence, this means the software designers add extra time at the beginning of a wakeup operation to make sure both devices are communicating, then more extra time at the end of an operation before the device is put back in idle mode to make sure all the data was transferred. However, with SiTimes SiT1552 TCXO real-time clock, its accuracy is within 5 PPM -- the lowest in the industry -- permitting the software writers to drastically cut down those buffer periods, thus saving power and extending battery life, especially for wearables.
"We weren't aware of this as a problem when we started talking to our customers about a TCXO version of our real-time clock, but they immediately told us about how a high-precision, real-time clock could significantly extend battery life -- especially on wearables," Sevalia told us.
SiTimes temperature controlled MEMS oscillator (TCXO) uses a unique 3-D chip stack with the tiny 125 micron thick MEMS die flipped and mounted between the solder bumps on the bottom of the application specific integrated circuit (ASIC) containing the electronics.
(Source: SiTime)
The SiT1552 TCXO uses the same TempFlat technology used in its SiT15xx -- a 20 to 100 PPM part announced last year. By adding on-chip temperature sensor and an analog temperature-to-digital converter (ADC) SiTime was able to increase precision to plus or minus 5 PPM. The SiT1552 TCXO real-time clock also claims the smallest footprint of any TCXO today, a 1.5 x 0.8 x 0.55 millimeter chip scale package (CSP), one sixth the size of quartz crystals. And it consumes less than one microAmp of power. The MEMS chip is so small and thin -- 400 x 400 x 125 microns -- that it fits between the solder balls on the bottom of the application-specific integrated circuit (ASIC) containing the electronics.
The SiT1552 is also marketed to device makers that need accuracy over long periods, such as smart meters, which need to stay accurate for 20 years or more. The device has a lifetime of 500 million hours and is covered by SiTime's lifetime replacement warranty, as are all its timing chips. The SiT1552 is in mass production now, and so far SiTime has shipped 220 million total timing chips since its founding in 2005.
责编：Quentin
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