SiTime mentioned above is selling oscillators that can be embedded in the same package as the microcontroller. I would say that's the way to go.
I wonder how SiLabs compares to the competition? Personally, I tend to favor MEMS platforms based on SOI that are DRIE:d into the structures. Mostly due to the simplicity and the use of monocrystalline Si. SiLabs deposit a pretty thick layer of poly-SiGe (SiGe can be deposited at pretty low temperatures which is critical if CMOS-wafers are the substrate that is deposited) that is formed into the resonator structure.
Guess in the end it's a question about the yield of the processes.
The 2mm x 2.5mm size is nice. It's disappointing how large a lot of the current oscillators are compared to the tiny chips around them. Sometimes the oscillator is bigger than the MCU.
My next question is, when can I get these integrated with the MCU on the same dice?
What are the engineering and design challenges in creating successful IoT devices? These devices are usually small, resource-constrained electronics designed to sense, collect, send, and/or interpret data. Some of the devices need to be smart enough to act upon data in real time, 24/7. Are the design challenges the same as with embedded systems, but with a little developer- and IT-skills added in? What do engineers need to know? Rick Merritt talks with two experts about the tools and best options for designing IoT devices in 2016. Specifically the guests will discuss sensors, security, and lessons from IoT deployments.