Source: Automobility blog from freescale.com by Cherif Assad
Sensors are proliferating in our cars. According to IHS, the MEMS sensor market continues to grow strong in automotive applications with compound annual growth revenue (CAGR) of 10% within the 2010-2015 timeframe.
With the emergence of electrification, the 12V battery (also known as a low voltage battery) is more and more solicited by the electronic equipment of the car and has to handle all modes of operation (drive, start, stop, and standby). 
The risk of shortage becomes real with unavoidable leakage current when the car is not in use. To mitigate the battery consumption when the car is stopped and the engine is switched-off, all ECUs (electronic control unit) connected to the battery are limited on a maximum stand-by current in order to not discharge the battery in a short time.
For the battery, the contextual sensing is about voltage, current, and temperature measurements. On one side, an analog die handles accurate building blocks to sustain each operating mode, power management, clock generation, and wake up options. The processing unit calculates data characteristics like dynamic internal battery resistance and supports customizable software tools to allow modular design and to increase levels of integration.
The stop/start function is currently expanding at OEMs with new car models. They know the battery needs a specific monitoring to guarantee some charging level to perform the stop/start function during idling and cranking modes. With the upcoming car electrification to lower the fuel consumption and comply with emission regulations, a second battery may also be necessary to handle the energy requirements. A battery sensor makes sense and fulfills Freescale’s Xtrinsic concept. The Xtrinsic MM912J637 intelligent battery sensor has been developed in that spirit, as well as the foreseen successor.