Smart Combinations
Whether it’s adding more capability or combining multiple sensor functions on a single device, the innovations in sensor technology are heading in the direction of integration. Manufacturers of sensors and sensor system solutions continue to develop highly integrated, high-performance devices.
Because they are the electronic devices that interact directly with the real world, sensors make up a key part of any embedded system. And, as the Internet-of-Things (IoT) phenomenon continues to ramp ever upward, sensor manufacturers have had to keep pace. As result, makers of sensors and sensor system solutions have been hard at work developing new products.
Sensors span a wide variety of sensor types and functions including: temperature, pressure, motion, gas detection, LIDAR and more. Factoring in the proliferation of IoT and intelligent edge applications, sensors are also moving to smaller, low-power designs to meet the new requirements of those systems.
Because there are so many different types of sensors, it’s perhaps too wide a topic for one article. With that in mind, this an overview of the latest developments and new products introduced over the past 12 months.
LIDAR SENSOR ARRAY
Automobiles are platforms of continuously evolving technology. Demand for LIDAR sensors is part of that mix. Aiming at just that sector, in March ON Semiconductor announced its RDM-Series silicon photomultiplier (SiPM) array. The device extends the LIDAR sensor capabilities to its broad portfolio of intelligent sensing solutions, according to On Semi. The company says the ArrayRDM-0112A20-QFN is the first automotive qualified SiPM product in the market, designed to feed the growing demands in LIDAR applications for the automotive industry and beyond (Figure 1).
The ArrayRDM-0112A20-QFN is a monolithic 1×12 array of SiPM pixels based on the company’s RDM process, which enables high sensitivity to near-infrared (NIR) light to achieve 18.5% photon detection efficiency (PDE) at 905nm. The high internal gain of the SiPM allows sensitivity down to the single-photon level, a feature that in combination with the high PDE, enables the detection of the faintest return signals. This results in the ability to range to greater distances even with low reflective targets.
SiPM technology has gained momentum in recent years and has become the sensor of choice for broad-market depth sensing applications due to its unique feature set, says the company. SiPMs have the ability to deliver the highest signal-to-noise performance for long distance ranging in bright sunlight conditions. Additional benefits, including lower supply biases and lower sensitivity to temperature changes, make it an ideal upgrade for systems that use legacy avalanche photodiodes (APDs). SiPMs are produced in a high-volume CMOS process, allowing for the lowest detector cost and therefore enabling broad-market LIDAR solutions.
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Using laser light to measure the distance of an object has spanned the fields of automotive, consumer and industrial applications. In automotive, LIDAR can be employed to improve safety and driver assistance systems (ADAS), aiding features such as lane keeping and traffic jam assist by complementing and providing redundancy with other sensing modalities. LIDAR is becoming commonly used for fully autonomous driving use cases, such as robotic transportation, to safely navigate the environment in real time. Benefiting from the high PDE of ArrayRDM-0112A20-QFN, LIDAR systems supporting these functions have been proven to range over 300 meters in distance. More distance gives more time for the vehicle to respond to unexpected obstacles. The ArrayRDM-0112A20-QFN is AEC-Q102 qualified and developed in accordance with IATF 16949.
INDUCTIVE POSITION SENSOR
Sensors are a key part of any motor control system. With that in mind, in January Renesas Electronics launched its magnet-free IPS2550 inductive position sensor. Featuring improved performance and easy customization, as well as total stray field immunity, and reduced weight and form factor, the IPS2550 is well suited for use as an absolute position sensor for high-speed motor commutation in passenger cars, heavy-duty commercial and off-road vehicles as well as motorbikes (Figure 2). With its optimized bill of materials, the new sensor allows developers to cost effectively tailor sensor design for their applications and maximize the performance of the sensor’s accuracy, says Renesas.
Based on Renesas’ inductive position sensing technology, the magnet-free IPS2550 delivers speeds up to 600krpm (electrical) and is designed around the motor, accommodating both off-axis (through shaft and side shaft) and on-axis positioning. System developers can match the number of sectors to pole pairs of the motor and cost-effectively boost accuracy compared with alternative sensing technologies.
Featuring total stray field immunity, the thin and light sensor also enables easier motor integration and offers the standard materials required for customers to manufacture their own resolver replacement—reducing bill of materials costs. The IPS2550 has been developed according to ISO26262 to support, as a single IC, the most challenging functional safety critical applications, capable of supporting up to ASIL-C(D) system-level requirements.
HYBRID POSITION SENSOR
Position sensors need to be precise and reliable. And, because they’re often used in harsh environment applications like industrial machinery, they also have to be fairly rugged. Along just those lines, in April Bourns introduced a hybrid position sensor for RS-485-based applications in certain harsh environments. Designed to meet the specifications of heavy-duty applications requiring long cycle life and high reliability, the Bourns Model HES38U-RS485 hybrid position sensor offers a rotational life of up to 5 million shaft revolutions with 10 turns of absolute position (Figure 3).
The advanced hybrid design enables the Model HES38U-RS485 to deliver enhanced linearity, resolution and accuracy. Highly repeatable and resistant to vibration/shock and fluid/dust ingress, this robust position sensor is an optimal solution for a variety of industrial feedback applications including patient platform positioning, 3D imaging position, pneumatic control valve position and actuator motor position as well as for automated manufacturing robotics, says Bourns.
The HES38U-RS485 features a 6mm diameter slotted shaft supported by a mechanical angle of 360 degrees (±10 degrees) and is available with customized longer cable lengths and in a servo mount configuration. It has an Independent Linearity specification of ±0.1% max, an IP65 seal rating and an operating temperature range of -40°C to +85°C.
TEMPERATURE SENSOR
Temperature sensing is critical in a whole host of applications where goods can be spoiled or systems damaged when temperatures exceed limits. Serving such needs, in September Maxim Integrated announced its MAX31825 digital temperature sensor that enables up to 64 devices per bus—all parasitically powered by the 1-Wire bus, drastically reducing wiring complexity. At the same time, Maxim released the MAX31889 digital temperature sensor, which features a combination of accuracy and power consumption, replacing expensive resistance temperature detectors (RTDs) in precise temperature-sensitive applications (Figure 4).
Sensitive processes and applications often require connecting multiple devices in a space-constrained system to measure temperature and protect processes, assets and equipment from unacceptable variation. According to Maxim, competitive solutions offer the ability to connect up to eight devices and require an additional wire for power. In contrast, the MAX31825 reduces design and wiring complexity by allowing up to 64 devices, all connected to the same parasitically powered 1-Wire bus, with the precision of ±1°C accuracy.
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Each MAX31825 device has a unique code, which can be optionally programmed with a location address, simplifying system design. The 1-Wire versatility improves system robustness by delivering an 8x reduction in necessary wiring compared to competitive two- or three-wire solutions. The MAX31825, which comes in a 6-bump WLP, also supports longer battery life and extends operational uptime with a low standby current of 2.5µA, ideal for consumer devices and factory automation.
According to Maxim, designers of highly reliable cold-chain pharma and other temperature-sensing applications can achieve high accuracy and robust system operation with these two new sensors. Variances as little as 2°C can adversely impact products and processes by limiting the producer’s ability to deliver quality products, thereby impairing the bottom line. Delivering precision measurement of ±0.25°C accuracy across a wide temperature range, the MAX31889 measures cold-chain pharma product temperatures at a fraction of the cost of RTDs and at 35% the power consumed by competitive solutions, says Maxim. The MAX31889 comes in a 6-pin µDFN package.
REFRIGERANT GAS SENSORS
Systems that use refrigerant technologies, including HVAC systems, are facing stricter compliance requirements that must be met by January 2023. Offering a solution, in November NevadaNano announced an expansion of its Molecular Property Spectrometer (MPS) Refrigerant Product Family with gas sensors for A1, A2L and A3 refrigerants. NevadaNano says its family of sensors is the first to meet the new North American Standards Developing Organizations and global IEC/CENELEC standards as well as AHRTI performance specifications for residential and commercial HVAC and cooling/refrigeration applications. As a result, the sensors are being adopted quickly by global HVAC and refrigeration leaders as they strive to meet compliance requirements (Figure 5).
The MPS Gas Sensor Family of A1, A2 and A3 refrigerant gas sensors deliver high performance in challenging HVAC environments with the industry’s lowest total cost of ownership (TCO) when compared to traditional catalytic bead and NDIR sensors, says the company. The MPS gas sensors accurately detect standard A1’s as well emerging A2L’s and A3’s without drift and “false positive” alarms that create costly service calls and frustrated customers.
The sensors are immune to “poisoning” so they won’t stop working when exposed to common household and industrial chemicals enabling lifetimes exceeding 10 years. Using these sensors reduces costs by ending the need to use and maintain multiple sensors in a single location or application. MPS’s versatile platform delivers solutions to detect multiple types of refrigerant gases in diverse applications.
The rugged design adapts to multiple markets and applications including residential and commercial HVAC, data center cooling, commercial, grocery store, cold chain refrigeration, and transportation and processing refrigeration. The sensors can quickly and accurately locate expensive refrigerant leaks and proactively mitigate costly refrigerant loss.
SMART PRESSURE SENSORS
Part of the integration trend in today’s sensors involves taking multiple sensor functions and combining them in one device. This is particularly useful for sensor types that complement one another, like pressure and temperature, for example. Doing just that, in April TDK InvenSense announced its InvenSense ICP-10125, part of the company’s SmartPressure family of the MEMS barometric pressure sensor platform (Figure 6). The company says that the ICP-10125 achieves the industry’s lowest pressure noise of 0.4PaRMS, attains the industry’s lowest power consumption of 1.3µA and ensures excellent temperature stability with a temperature coefficient of ±0.5Pa/°C.
The ICP-10125 device combines a barometric pressure and a temperature sensor in a small 3.55mm × 3.55mm × 1.45mm chimney package with waterproofing gel, providing IPX8 waterproofing to 10ATM. The uniform machined lid and chimney with groove enable easier handling at production and assembly of customer products. The solution is aimed at the fitness, smart watch and portable device markets that assist in fitness activity monitoring, location tracking for E911 calls, and indoor/outdoor navigation (dead-reckoning, floor/elevator/step detection).
The InvenSense SmartPressure family uses an innovative capacitive MEMS architecture to deliver lower power consumption and lower noise than competing pressure sensors technologies. With its ultra-low noise and low power consumption, ICP-10125 is ideally suited for wearable fitness monitoring and battery-powered IoT. It can measure height change as small as 8.5cm, less than the height of a single stair step. A comprehensive development kit (DK-10125) and evaluation platform are also available along with necessary software to enable quick-to-market development of customer systems.
HALL EFFECT SENSORS
The ongoing demand for higher performance in industrial systems is driving the need for more precise current measurement, in addition to reliable operation, which often comes with the cost of increased board space or design complexity. Addressing this issue, Texas Instruments (TI) applied its expertise in both isolation and high-precision analog to the TMCS1100 and TMCS1101, enabling engineers to design systems that will provide consistent performance and diagnostics over a longer device lifetime, keeping its solution size compact without increasing design time (Figure 7).
TI claims the two devices as the industry’s first zero-drift Hall-effect current sensors. The TMCS1100 and TMCS1101 enable the lowest drift and highest accuracy over time and temperature while providing reliable 3kVrms isolation, which is especially important for AC or DC high-voltage systems such as industrial motor drives, solar inverters, energy-storage equipment and power supplies.
The zero-drift architecture and real-time sensitivity compensation of the TMCS1100 and TMCS1101 enable extremely high performance, even under operational conditions such as temperature changes and equipment aging. With an industry-leading total sensitivity drift over temperature of 0.45%, maximum, which is at least 200% lower than other magnetic current sensors, and a maximum full-scale offset drift of less than 0.1%, the devices provide the highest measurement accuracy and reliability across a wide range of current. Further, a 0.5% lifetime sensitivity drift, which is at least 100% lower than other magnetic current sensors, significantly reduces the performance degradation associated with system aging over time.
Additionally, the ultra-high accuracy of the TMCS1100 (1%, maximum) and TMCS1101 (1.5%, maximum) eliminates the need for device calibration, which reduces equipment maintenance over time. The devices also provide typical linearity of 0.05%, which minimizes signal distortion and helps maintain accuracy across the extended industrial temperature range (-40°C to 125°C). Both devices support a ±600V lifetime working voltage—up to 40% higher than competitive devices in the same 8-pin SOIC package and have been rigorously tested beyond industry-standard UL and VDE requirements for greater design margin and an extended device lifetime.
SENSOR COLLABORATION
For its part, STMicroelectronics (ST) offers a wide variety of sensor products, several of which were released over the past six months. In November, ST teamed up with Qualcomm by developing software solutions using technology from Qualcomm Technologies through the Qualcomm Platform Solutions Ecosystem program.
In this program, ST is contributing pre-validated software to OEMs for its MEMS and other sensing devices to deliver advanced features to the next generation of smartphones, connected PCs, IoT and wearables. Most recently, Qualcomm Technologies pre-selected ST’s latest high-accuracy, low-power, motion-tracking sensor IC with intelligent sensor software, along with ST’s most accurate pressure sensor, for use in its latest advanced 5G mobile reference platforms (Figure 8).
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The motion-tracking sensor is ST’s new iNEMO LSM6DST, a 6-axis inertial measurement unit (IMU) that integrates a 3-axis digital accelerometer and a 3-axis gyroscope into a compact and efficient System-in-Package (SiP). ST claims it offers the industry’s lowest power consumption—0.55mA in high-performance mode and as little as 4µA in accelerometer-only mode. As a result, the LSM6DST enables always-on high-accuracy motion tracking with minimal impact on power consumption. In concert with ST’s low-noise (0.65Pa), high-accuracy (±0.5hPa), and industry-first I3C-enabled LPS22HH pressure sensor, the pair provides highly accurate location tracking while meeting the most restrictive power budgets.
For imaging applications, the LSM6DST fully supports EIS and OIS (Electronic and Optical Image Stabilization) applications as the module includes a dedicated configurable signal processing path for OIS and auxiliary SPI, configurable for both the gyroscope and accelerometer and, in turn, the Auxiliary SPI and primary interface (SPI/I²C and MIPI I3CSM) can configure the OIS.
Benefiting from ST’s mature low-power ThELMA1 process technology, the LSM6DST supports and simplifies integration in low-power circuit designs and offers I²C, MIPI I3C or SPI from the sensing element to the application. It also contains a 9KB FIFO to allow dynamic data batching and 16 finite state machines that recognize programmed data sequences from the sensor and further reduce system-level power consumption.
CONDITIONING MONITORING KIT
System developers have come to understand that sensors need to be designed with the overall system in mind. This is particularly true for IoT and “Smart” applications like Smart Buildings. With that in mind, in February Infineon Technologies launched its XENSIV Predictive Maintenance Evaluation Kit (Figure 9). The kit was co-developed with the IoT service provider Klika Tech and is powered by the cloud service provider AWS to offer an end-to-end solution for system developers, says Infineon.
The kit includes hardware (sensors, microcontroller, embedded security), software as well as CloudFormation templates. It provides a starting point for quick and easy evaluation of sensor-based condition monitoring and predictive maintenance. The target applications involve heating, ventilation and air conditioning (HVAC) equipment as well as motors, fans, drives, compressors, refrigeration and other components of Smart Buildings.
The XENSIV Predictive Maintenance Evaluation Kit is an extension for the XMC4700 XMC Relax Kit. It can be equipped with XENSIV sensor satellite boards with a broad range of sensors for data collection and condition monitoring such as: Airflow measurement at the compressor based on the DPS368 barometric pressure sensor; current measurement at the fan and compressor based on the TLI4971 current sensor; position sensing of the motor with TLI493D-W2BW 3D magnetic sensor; sound anomaly detection in the unit with the IM69D130 MEMS microphone; linear movement vibration measurement with TLE4997E Linear Hall sensor; opened and closed lid detection with TLE4964-3M Hall sensor; and speed and direction measurement with TLI4966G Double Hall sensor.
Data processing is done with Infineon’s XMC industrial microcontroller XMC4700 powered by Arm Cortex -M4. And secured connection and authentication as well as multi-account registration is provided by the company’s OPTIGA Trust M embedded security solution.
The software provided fully supports the FreeRTOS kernel. AWS Cloud integration is completed by full AWS CloudFormation templates and a software application stack. A GUI and basic anomaly detection are also included. For connectivity, Wi-Fi and Ethernet are integrated on-board, as well as a mikroBUS ClickBoard interface for extended connectivity. Multi-account registration is supported with OPTIGA Trust M embedded security solution.
IoT TRACKING KIT
Another company taking the “kit” approach is TT Electronics. In October, the company announced its S-2CONNECT Pro Tracking and Monitoring Kit for rapid IoT development. The kit can be deployed to connect, track, sense and monitor applications such as asset tracking, cold chain, smart home and broader industrial IoT scenarios (Figure 10).
The kit features “out-of-the-box” hardware from the TT Electronics S-2CONNECT family, including the S-2CONNECT Hub and S-2CONNECT Sense device, which incorporate temperature, humidity, light and acceleration sensors. An embedded SIM with three months of cellular connectivity, a data package of 25MB per month and a power supply with interchangeable blades for global use are also included.
The Pro Kit comes with access to cloud-based services provided by TT Electronics including database, MQTT broker, microservices and firmware hosting. Access to the user interface for managing device configuration, provisioning,and monitoring is offered exclusively by the S-2CONNECT Portal for the duration of the subscription.
LTE-M and NB-IoT are excellent connectivity options for industries looking to take advantage of LPWAN (Low Power Wide Area Networks) technology. They enhance the battery life of devices and connect devices that have previously been hard to reach. With connected products, manufacturers can extend their customer relationships far beyond the assembly line. LTE-M and NB-IoT are designed explicitly for the IoT.
S-2CONNECT Hub uses the latest GNSS and LTE technology to provide real-time positioning data and transmission of that data over LTE Cat M1 or NB-IoT with 2G-fallback for global coverage. The Hub serves as the gateway for the S-2CONNECT Sense device. S-2CONNECT Sense is a Bluetooth Low Energy (BLE) device designed to record temperature, humidity, light and impact data and then transfer it to the nearest S-2CONNECT Hub. The Sense supports 256KB/8MB memory/flash and ARM Cortex M4 processor. 
RESOURCES
Bourns | www.bourns.com
Infineon Technologies | www.infineon.com
Maxim Integrated | www.maximintegrated.com
NevadaNano | www.nevadanano.com
ON Semiconductor | www.onsemi.com
Renesas Electronics | www.renesas.com
STMicroelectronics | www.st.com
TDK InvenSense | www.invensense.tdk.com
Texas Instruments | www.ti.com
TT Electronics | www.ttelectronics.com
PUBLISHED IN CIRCUIT CELLAR MAGAZINE • JUNE 2021 #371 – Get a PDF of the issue
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Jeff served as Editor-in-Chief for both LinuxGizmos.com and its sister publication, Circuit Cellar magazine 6/2017—3/2022. In nearly three decades of covering the embedded electronics and computing industry, Jeff has also held senior editorial positions at EE Times, Computer Design, Electronic Design, Embedded Systems Development, and COTS Journal. His knowledge spans a broad range of electronics and computing topics, including CPUs, MCUs, memory, storage, graphics, power supplies, software development, and real-time OSes.
