At this point, the SiT1552 32 kHz MEMS TCXO is not offered as a VCXO (VCMO).
Typically, we've seen the use of MHz frequencies in discrete PLLs, and so we do offer MHz oscillators and TCXOs with the voltage control (VC) function. Pullability is up to 1600 PPM on the oscillators. Datasheets for those devices are here.
Thank you for your comments. Yes, the SiT1552 is a highly-stable, 5PPM MEMS TCXO (oscillator). It is not equivalent to the DS3231 Real Time Clock IC, though Maxim does offer a DS3231M which is based on a MEMS reference resonator.
On the pricing - the SiT1552 is available for $1.90 in low-volume quantities (10KU EAU). However, like any other semiconductor, pricing drops signficantly in high volumes because of the benefit of scale. If you would like higher volume pricing, please feel free to email me with project details or contact a SiTime representative, and we will be happy to help you.
Reading the SiT1552 data sheet, I realize it is only an oscillator. The term "real-time clock", or RTC, is usually only used when the device contains additional dividers and registers to provide values for hours, minutes, seconds, etc.
Other real-time clock devices with similar accuracy and low power have already been available for quite a few years, such as the Maxim DS3231, which has an accuracy within 3.5ppm over the entire -40 C to +85 C temperature range. But it comes in a package that is much, much larger than the SiT1552. Also, if I understand the data sheets correctly, the DS3231 adjusts its temperature compensation only once every 64 seconds, whereas the SiT1552 does it every 350 msec., which would be much better for rapidly changing temperatures.
Saves 200% of the power? If it used half the power, it would save only 50%, if it saved 100% of the power it would be using no power at all, and if it saved 200% of the power it would be generating power instead of consuming it!!
Regarding the accuracy comment - please see below for a stability plot over temperature of SiTime's 32 kHz MEMS TCXO and a typical 32 kHz tuning fork quartz resonator or oscillator. The SiTime TCXO is much more accuracte (stable) than the quartz device. The two red lines show the envelopes of stability variation of different devices from various manufacturers.
The space gain is impressive, and timing wise it would mean +/- 13 seconds a month or so. This equals +/- 2 minutes and 38 seconds in a year, which means it is as accurate as NON TCXO quartz, unless I'm mistaken. What about power consumption?