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Sensor Solutions: Focus on STMicroelectronics

Continuing our series examining major players in the sensor area, in this article we will take a close look at the sensor products and technologies offered by the global semiconductor company STMicroelectronics. Calling itself the world’s top MEMS manufacturer, the company successfully develops semiconductor solutions across the spectrum of microelectronics applications. ST supplies such products as smart sensors and hubs; accelerometers; automotive sensors; gyroscopes; humidity sensors; MEMS devices; pressure, proximity, temperature, and e-Compass sensors; and iNEMO-inertial modules and touchscreen controllers, making ST’s portfolio extremely broad and deep.

Research house IHS, in a recent report, asserts that sensor hubs — a focus of ST —will play a key role in the future of sensing. These hubs offload tasks from power-laden application processors, and enable a single battery charge to power mobile devices longer, and enable “always on” performance. Shipment growth is estimated at triple-digit levels in 2014 with 658.4 million units, up 154 percent from 259.6 million units in 2013, according to IHS. From 2014 through 2017, IHS expects there will be an increase of 1,300 percent to shipments of a whopping 1.3 billion units.

STMicroelectronics uses an external hub approach, as does Atmel, Texas Instruments and NXP, for smartphones including Apple’s iPhone 5s, Samsung’s Galaxy S5, and the Motorola Moto X. Another of its sensor hub approaches is an MCU combined with single or multiple sensors such as accelerometers and gyroscopes. InvenSense and STMicroelectronics are the main providers of solutions using this approach, while Bosch, Freescale Semiconductor, and Kionix offer products in this segment as well.

ST’s sensor portfolio ranges from discrete to fully-integrated solutions. It uses high-performance sensor fusion to improve the accuracy of multiaxis sensor systems and it has MEMS foundries, assembly, and test capabilities, allowing it to be a complete in-house dual source for its customers.

ST’s MEMS analog and digital accelerometers offer up to ±400g acceleration full scale and from 1.71 to 3.6 V supply voltage, and are suitable for ultra-low-power applications. Features include small size, embedded, low-power mode, auto wake-up functions and a FIFO buffer to store data, reducing the host processor loading and system power consumption.

The ST LIS2DH MEMS digital output motion sensor, (Figure 1), is an ultra-low-power, high-performance three-axis feature-rich “femto” accelerometer. With digital I²C/SPI serial interface standard output and dynamically user selectable full scales of ±2 g/±4 g/±8 g/±16 g, it is capable of measuring accelerations with output data rates from 1 Hz to 5.3 kHz. It is available in a small, thin plastic land grid array package (LGA) and operates over a temperature range of -40° to +85°C.

Figure 1: Block diagram of the LIS2DH.

Applications include motion-activated functions, display orientation, shake control, pedometers, gaming and virtual reality input devices, impact recognition, and logging.

On the gyroscope front, the ST L3GD20 (Figure 2) is a low-power, three-axis angular rate MEMS motion sensor with a sensing element and an IC interface that provides a measured angular rate through a digital interface (I²C/SPI). The sensing element is manufactured using a dedicated micro-machining process to produce inertial sensors and actuators on silicon wafers.

Figure 2: The ST L3GD20. The vibration of the structure is maintained by drive circuitry in a feedback loop. The sensing signal is filtered and appears as a digital signal at the output.

The CMOS-based IC interface allows a high level of integration to design a dedicated circuit that can match sensing element characteristics. The L3GD20 has a full scale of ±250/±500/±2,000 dps and can measure rates with a user-selectable bandwidth. The sensor offers high performance combined with low power consumption for demanding applications and extended battery life and embedded FIFO for smart data storage and power saving. It also starts up rapidly, providing high responsiveness and system efficiency. Also available in a plastic land grid array (LGA) package, it operates within a temperature range of -40°C to +85°C.

ST’s three-axis gyroscopes have a single sensing structure for motion measurement along all three orthogonal axes compared with other solutions that use two or three independent structures. Applications include gaming and virtual reality input devices, motion control with MMI (man-machine interface), GPS navigation systems, appliances, and robotics.

One of ST’s claims to fame is the iNEMO inertial sensor modules that integrate complementary sensors and offer compact, robust, and easy-to-assemble solutions compared with discrete MEMS products.

iNEMO delivers motion-sensing systems at the high performance levels required for demanding applications. The company promotes this technology with its global iNEMO Design Challenges for students and engineers to design innovative products using iNEMO smart multisensor technology.

The LSM330DLC iNEMO inertial module (Figure 3) is a system-in-package that contains a 3D digital accelerometer and a 3D digital gyroscope. Manufactured using ST’s specialized micromachining processes, the IC interfaces are CMOS based.

The LSM330DLC accelerometer and gyroscope sensors can be either activated or separately put in low-power/power-down mode for applications optimized for power saving.

Figure 3: The LSM330DLC is available in a plastic land grid array (LGA) package.

Benefits include multiple sensors in a single package without a performance hit, smaller form-factors, thermal and mechanical stability controls, and other consumer electronics devices

The single-chip iNEMO solutions bring motion sensing systems to the level required for such demanding applications as enhanced gesture recognition, gaming, augmented reality, indoor navigation, and localization-based services.

STMicroelectronics also makes available a wide variety of sensor dev boards/kits to help engineers use its product in current and future designs. ST's MEMS-based motion sensors are all supported by their own evaluation kits that enable the acquisition, through an analog or digital interface, of acceleration data sensed by accelerometers, gyroscopes, e-compasses, and pressure sensors with the support of a dedicated software in many cases. For sensors with analog output, sensing data are converted by a low-noise capacitive amplifier into an analog voltage, while for digital sensors, the signals measured by the device are read by an STM32 microcontroller mounted on the board and sent to a PC via USB link for further processing.

For example, STEVAL-MKI013V1 is an adapter board designed to allow the evaluation of the LIS302DL, a low-power three-axis linear accelerometer with digital output. The adapter board offers an effective solution for fast system prototyping and device evaluation directly within the user’s own application. The STEVAL-MKI0013V1 is designed to be plugged into a standard DIL 24 socket. It provides the user with the complete LIS302DL pinout, and comes ready-to-use with the required decoupling capacitors on the VDD power supply line.

In summary, STMicroelectronics is highly competitive in the sensor arena and is able to differentiate its products in an effective way through innovation both in its sensor families and in its manufacturing processes. For more information on the parts discussed here, use the links provided to access product pages on the Hotenda website.