It was the summer of 2012 when a frantic scramble occurred deep within a lab in Silicon Valley. At a time when wearables and other IoT markets were just starting to ramp, a show stopping problem was discovered. With wearables shipments in the low millions for the first time, this problem had to be solved. Panicked, highly skilled engineers on multiple coasts and across continents attempted to solve the problem. The quartz crystal on the MCU would not reliably start.
How can that be? It’s just a quartz device, ancient technology—if it can be called technology. Almost a hundred years of development of quartz manufacturing means that there should be no surprises. What happened? Neither the silicon companies nor the end system hardware designers were prepared for this. The solution rested with the engineers that developed the crystal itself.
With over a hundred million IoT and wearables shipments behind us, the root cause is now well known. In order to conserve power, IC designers reduced the transconductance (gm) of the Pierce oscillator that drives the 32.768kHz quartz crystal. By reducing the gm, the drive of the circuit was inevitably weakened. The Pierce oscillator would eventually experience trouble driving conventionally plated crystals that present a heavier capacitive load. New low power MCU’s can run into trouble driving just a couple extra picoFarads of capacitance. The extra load limits the amount of margin in the design, especially when considering all process corners and full operating temperature range.
In 2012, most 32.768kHz quartz crystals were plated to present a CL of about 9pF. Traditionally, the gm of Pierce oscillator circuits could overcome this plating load and sustain oscillation, but that all changed. MCU’s now required crystals with plating load far lower than ever conceived. The solution was to jump to new plating designs that achieved CL of 6pF—a 33% reduction.
The combination of equivalent series resistance (ESR) and shunt capacitance (C0) also affected the loading that the Pierce oscillators perceived. The ESR and C0 had to be simultaneously lowered along with CL. Considering that ESR and CL are exclusively optimizable parameters in quartz plating design, executing new low loading levels required advanced engineering and world class manufacturing. The strenuous requirements forced many suppliers to avoid the change or risk failure. The wearables industry was about to experience a crunch due to the mismatch between the crystal and the MCU’s Pierce oscillator—it was very clear that existing crystals were not optimized for IoT applications.
Fortunately, engineers with extensive timing applications experience and advanced proprietary tools that accurately measure the operating point of Pierce oscillators addressed this challenge. Abracon’s engineers developed the industry’s first 6pF tuning fork crystals that simultaneously holds a maximum 60kΩ ESR. Problem solved. IoT devices could ship using this newly engineered crystal; a crystal engineered for the IoT.
Realizing that the IoT would incessantly pressure IC designers to continuously reduce power consumption, Abracon’s engineers continued to innovate. Within 2 years, a 32.768kHz tuning fork crystal with 4pF plating load optimized for IoT applications was introduced. The additional 33% reduction in load capacitance is now enabling the next wave of hardware designs powered by energy saving MCUs.
Keeping on pace with market requirements, Abracon announced the recent availability of a broad family of IoT optimized crystals with 3pF tuning forks.
Why is Abracon the Heartbeat of the IoT™? Put simply, Abracon addressed a major challenge when no one else would. The IoT did not start in 2012. In fact, the IoT has existed for decades. Yet, the recent explosion and next level of market dominance requires a new level of power savings design in energy saving MCU’s and RF chipsets. With those designs follows a need for IoT optimized crystal technology. Abracon has been at the forefront of this paradigm shift, triggered in the last 5 years. Coupled with other IoT centric products and technologies such as antennas, compact inductors, 22nA RTCs, and wireless charging coils, Abracon advocates for and executes on the unique challenges of IoT designs.
Pictured above (left to right): Brooke Cushman, Associate Engineer; Chen Li, Product Engineer; Syed Raza, VP of Engineering; Ying Huang, Director of Procurement
About Abracon, LLC
Founded in 1992, and headquartered in Spicewood, Texas, Abracon is a leading global manufacturer of passive and electromechanical timing, synchronization, power, connectivity and RF solutions. Abracon offers a wide selection of quartz timing crystals and oscillators, MEMS oscillators, real time clocks (RTC), Bluetooth modules, ceramic resonators, SAW filters and resonators, power and RF inductors, transformers, circuit protection components and RF antennas and wireless charging coils. The company is ISO9001-2008 certified with design & application engineering resources in Texas and sales offices in Texas, California, China, Taiwan, Singapore, Scotland, Israel, Hungary, UK, and Germany. Abracon’s products are offered through its global distribution network. For more information about Abracon, visit www.abracon.com.
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