Tuesday, June 14, 2011

The 'internet of things' is driving demand for mixed signal MCUs

There is increased activity around the ‘internet of things’; the ability to create networks of small devices that monitor and control our surroundings to create a sort of ‘augmented reality’.

A recent development is NXP’s intention to open-source its JenNET IP protocol stack, which uses the IEEE 802.15.4 MAC and PHY as its underlying platform and employs the IPv6 protocol to extend the network’s addressable nodes to what is often termed as ‘effectively limitless’. It is this potential to give any electronic device its own IP-addressable profile that will lead to the ‘internet of things’ concept becoming reality.

However, in addition to uniquely identifying these ‘things’, it follows that the ‘things’ should do something useful and, increasingly, the application that is most often cited is monitoring and control. Consequently, data gathering using some form of ‘smart’ sensor is expected to constitute a large part of activity for the ‘internet of things’.

A market report by analyst IDC and cited by Intel states that by 2015 there could be 15 billion devices with an embedded internet connection, more than two for every single person on the planet today. In reality, as smart sensor applications flourish, the number of connections could grow beyond this figure rapidly, and that will be enabled in large part by the falling cost of developing and deploying connected devices. A major element of that cost will be the embedded intelligence and it is here that many IDMs are focusing their attention, in developing low power, low cost MCUs that meet the commercial and technical requirements of this emerging application space.

Mixed signal MCUs which also integrate wireless connectivity are already available, they will likely become more prolific in the future. However, for many applications, integrating the wireless connectivity may be less appealing than a two-chip solution, at least while the battle over which wireless protocol will prevail still rages. For this reason, perhaps, there is more activity around developing ultra-low power MCUs that focus on interfacing to ever smarter sensors.

Marking its entry into the MCU market, ON Semiconductor recently introduced its first mixed-signal MCU which focuses on applications that demand precision, as well as low power. ON Semiconductor recently acquired Sanyo Semiconductor and, with it, a portfolio of 8 and 16-bit MCUs. However, for its first in-house development, ON Semi chose the ARM Cortex-M3 32-bit core, which it has married with some mixed signal elements to create the Q32M210. It claims the device has been developed to target portable sensing applications that require high accuracy, predictable operation and the ever-present power efficiency.

ON Semi is more accustomed to developing custom ASICs rather than its own products, however through a number of other acquisitions it believes it has accrued the expertise necessary to address the needs of ‘niche’ applications, where precision is valued. It is the company’s experience in developing niche mixed signal products that forms its credentials, not least in the development of hearing aids that use highly accurate ADCs and a bespoke DSP technology.

The analogue front-end (AFE) used in the Q32M210 features dual 16bit ADCs and configurable op-amps, which result in a true ENOB of 16bits across the power supply range. This is enabled, in part, by an uncommitted charge pump that can be used to extend the operational lifetime of the battery supply. ON Semi claims the charge pump can be used to deliver a consistent 3.6V to the AFE, even when the battery supply has dropped to 1.8V. This could significantly extend the usable lifetime of any device empowered by the Q32M210.

The additional peripherals provide a USB interface, as well as LED/LCD drivers and push-button interfaces. Coupled with the programmable sensor interface, this positions the device as a system-on-chip solution for a range of applications and specifically portable medical devices, where its accuracy will be valued.

The AFE used in the Q32M210 is clearly intended to differentiate it from the competition, in terms of both accuracy and power consumption. However ON Semi isn’t the only device manufacturer to acknowledge the importance of mixed signal performance.

Information is shared by www.irvs.info

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