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Analog IC Advances Target Industrial Automation

Written by Jeff Child

Factory Focus

Analog and mixed-signal ICs play important roles in industrial automation and process control applications. These systems applications depend heavily on innovations in amplifiers, data converters, sensor solutions and more.

Today’s factory environments are filled with motors to control, sensors to link with and measurements to automate. Recognizing the opportunities in those industrial systems, analog and mixed signal IC vendors are keeping pace by rolling out diverse solutions to meet those needs. With all that in mind, over the past 12 months, manufacturers of analog ICs have released a rich variety of chips to meet a diverse set of industrial needs. These products include high-precision amplifiers, converters, sensor technologies and more.

PRECISION VOLTAGE SENSING
Exemplifying these trends, in October, Texas Instruments (TI) put its focus on voltage sensing for industrial systems when it introduced a reinforced isolated amplifier. The company claims that the devices provide the industry’s highest precision and working voltages and longest lifetime reliability. The combination of better nonlinearity, lower offset and gain error and higher temperature stability, is expected to enable engineers to overcome performance limitations and design high-precision systems.

The new amplifier is designed for isolated voltage sensing in factory automation and control, grid infrastructure, rail transport and motor drive applications. TI’s capacitive isolation technology enables long lifetimes and 50% higher working voltages than required by isolation industry standards, common-mode transient immunity (CMTI) of up to 80 kV/µs and robust operation over an extended industrial temperature range of -55°C to +125°C.

The high-precision ISO224 (Figure 1) enables more accurate measurements of ±10-V signals, which are widely used in industrial applications, with 25% better nonlinearity, eight times lower gain error, lower offset drift and faster system response than similar competitive devices, according to TI. Engineers can reduce board space with the ISO224’s 60% smaller package than the previous-generation ISO12x amplifiers as well as its output that supports direct connection to an analog-to-digital converter (ADC) with 5-V input. The ISO224 also features a single, high-side supply with integrated voltage detection that simplifies the design and system-level diagnostics.

FIGURE 1 -The high-precision ISO224 enables more accurate measurements of ±10-V signals, which are widely used in industrial applications, with 25% better nonlinearity, eight times lower gain error, lower offset drift and faster system response than similar devices.

SPEED AND PRECISION
In June, Texas Instruments (TI) introduced three new amplifiers that offer a combination of high speed and high precision, allowing designers to create more accurate circuits for error-sensitive industrial applications. With maximum supply voltages ranging from 27 V to 36 V, the new devices support more precise measurement and faster processing.

Designers can select the amplifier architecture that meets their system requirements, with input voltages, bandwidths and key features. The OPA2810 is a 27-V junction gate field-effect transistor (JFET)-input dual op amp with 120-MHz bandwidth and 500-µV maximum offset voltage. The OPA189 is a 36-V zero-drift op amp with 14-MHz bandwidth and is multiplexer (MUX) friendly. And finally, the THS3491 is a 32-V current-feedback amplifier with 900-MHz small-signal bandwidth and ±420-mA output current.

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The high bandwidths of the OPA2810 and OPA189 enable high-gain configurations and faster response times for more accurate measurements. Designers can use the THS3491 current-feedback amplifier’s wide small-signal bandwidth, high slew rate and output current of ±420 mA to achieve low distortion and high output power levels. The THS3491 is capable of 10-Vpeak-to-peak output levels at 200 MHz into 100-Ω loads for test and measurement systems, such as arbitrary waveform generators, laser diode drivers and high capacitive load drive applications.

With a maximum offset and lowest voltage noise of 5.7 nV/√Hz for 27-V amplifiers in the 100- to 200-MHz bandwidth range, the OPA2810 op amp allows engineers to achieve more precise measurements in data-acquisition and signal-processing applications. According to TI, the OPA189 is the widest bandwidth zero-drift op amp with the lowest noise of 5.2 nV/√Hz. With a low maximum drift of 0.02 μV/°C, the OPA189 also minimizes temperature error without calibration, increasing system accuracy over an extended temperature range.

The 120-MHz OPA2810 op amp has a current consumption of 3.6 mA, while providing excellent signal-to-noise ratio and distortion. Designed for applications that require high gain and low distortion in power-sensitive designs, the OPA189 is the lowest power zero-drift op amp with a 14-MHz bandwidth. This device enables engineers to design high-resolution, noise-sensitive industrial systems while only consuming 1.3 mA of quiescent current, which can benefit analog input modules, and battery and LCD test equipment.

DAC FOR FACTORY AUTOMATION
Industrial automation ranks as a key focus for analog IC manufacturers. As a result, vendors have rolled out a steady stream of converter products tuned for such applications. For example, in May, Analog Devices (ADI) introduced the AD5758 digital-to-analog converter (DAC) (Figure 2). It incorporates the company’s 2nd-gen Dynamic Power Control (DPC) to enable high density AOUT modules without requiring de-rating—the need to turn off channels due to thermal build up—resulting in lower cost, more compact designs. This single-channel current/voltage DAC with DPC is designed for channel-to-channel isolated industrial applications in factory automation and process automation. According to ADI, the AD5758 is the company’s lowest power industrial DAC.

FIGURE 2 – The AD5758 is a single-channel current/voltage DAC with DPC is designed for channel-to-channel isolated industrial applications in factory automation and process automation. According to ADI, the AD5758 is the company’s lowest power industrial DAC.

The AD5758’s 5 mm x 5 mm size provides a small footprint and its robust construction requires fewer external protection components, supporting smaller, lower-cost designs. It is engineered with advanced diagnostics that provide visibility to system performance for higher reliability and planned maintenance schedules. The AD5758 also includes output fault protection circuits to safeguard the DAC in the event of a miswiring incident.

With its acquisition of major analog IC competitor Linear Technology, a couple years ago, ADI added numerous new industrial-oriented chips to its portfolio. Introduced back in April, an example product from that Power by Linear group is the LTM4653, 58 VIN step-down µModule Regulator. The LTM4653 can safely operate from unregulated or fluctuating 24 V to 48 V input supplies in noisy environments such as factory automation and industrial robotics.

The LTM4653 integrates input and output filters in a package, enabling the device to meet the EN55022 Class B EMC standard for information technology equipment. The LTM4653 has the same architecture as the LTM4651, 58 VIN, 4 A inverting µModule regulator, so the combination of the LTM4651 and LTM4653 is ideal to generate a pair of positive and negative voltages in a system.

The output voltage is adjustable with one resistor from 0.5 V to 94% of VIN. This wide output voltage range provides the versatility of using one product to generate common system bus voltages of 3.3 V, 5 V, 12 V and 24 V. The peak efficiency at 24 VIN to 5 VOUT is 92%. The LTM4653 delivers 4 A of output current up to 70°C ambient at 48 VIN to 5 VOUT without a heatsink or airflow. Multiple devices can be paralleled for higher current applications. The switching frequency is adjustable by an external single resistor or can be synchronized to an external clock from 250 kHz to 3 MHz.

The LTM4653 houses a switching regulator controller, power switches, inductor and other supporting components in a 15 mm x 9 mm x 5.01 mm BGA package. Only the bulk input and output filter capacitors are needed to complete the design. The device’s operating temperature range is –40°C to 125°C

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SENSOR TRANSMITTER
Industrial automation systems are typically jam packed with a variety of sensors, requiring reliable interfacing between sensors and control systems. With just that in mind, in February, Maxim Integrated Products announced the MAX12900, an ultra-low power, highly integrated 4 mA to 20 mA sensor transmitter (Figure 3). Embedded system developers can use it to create small, low power and highly accurate designs for industrial automation system. Ideal applications include industrial automation and process control, loop-powered 4 mA to 20 mA current transmitters, remote instrumentation and smart sensors.

FIGURE 3 – The MAX12900 is an ultra-low power, highly integrated 4 mA to 20 mA sensor transmitter. It is designed for applications including industrial automation and process control, loop-powered 4 mA to 20 mA current transmitters, remote instrumentation and smart sensors.

Today’s system designers must develop enhanced 4 mA to 20 mA sensor transmitters with several considerations in mind. These include improved measurement accuracy over a wide temperature range and reduced size to fit in a small enclosure. In addition, they are required to meet a tight current budget of their overall sensor transmitter system, which can be as low as 4 mA.

HIGH SYSTEM ACCURACY
The MAX12900 increases system accuracy with 10 ppm/°C voltage reference for up to 3.5x lower drift compared to traditional solutions. The small footprint (5 mm x 5 mm package size) of the MAX12900 integrates 10 optimized building blocks that results in a significant space savings of 20%-50% versus traditional 4 mA to 20 mA sensor transmitter implementations.

The addition of an integrated high voltage LDO and power sequencing capability simplifies the power up of the 4 mA to 20 mA sensor transmitter. Its reduced current consumption for low power requires just 250 µA of current maximum, enabling up to 50% power savings compared to traditional solutions. The new MAX12900 solution reduces implementation complexity, generating system cost savings by converting pulse width modulation data from a microcontroller (MCU) into current over a 4 mA to 20 mA loop with two, three, or four wire configurations. The MAX12900 is available in a 32-pin TQFN package and operates over a wide industrial temperature range of -40°C to +125°C.

More recently, Maxim Integrated introduced, in August, its MAX22445 5k VRMS four-channel reinforced digital isolator. The company claims the chip delivers up to 2x greater throughput at 4x lower power consumption versus competing solutions. The MAX22445 was designed to provide reliable communication across the isolation barrier to ensure safe operation of compact industrial equipment (Figure 4).

FIGURE 4 – The MAX22445 is 5k VRMS four-channel reinforced digital isolator. It provides 0.41 mA per channel current consumption and 0.74 mW power consumption at 1 Mbps with VDD at 1.8 V.

In high-voltage equipment, digital isolators provide signal isolation and level-shifting for proper operation of many circuits, while also protecting users from dangers such as electric shock. Yet, not all of these isolators are alike as many consume a large amount of power, generate significant heat and introduce large propagation delays, limiting system reliability and throughput. Overcoming the shortcomings of other digital isolators, the MAX22445 delivers reinforced, dual insulation barrier isolation for fast digital signals. The IC, which mitigates the dangers of high-voltage power, transfers signals of up to 200 Mbps with significantly less power than competitive solutions. It is available in a 16- pin wide-body SOIC package with 8 mm of creepage and clearance.

The device provides 0.41 mA per channel current consumption and 0.74 mW power consumption at 1 Mbps with VDD at 1.8 V. The MAX22445’s maximum propagation delay of 10.5 ns and maximum data rate of 200 Mbps enable fast and accurate data acquisition and high-speed interfaces with wide timing margins. Dual barriers of isolation provide 5k VRMS and 10 kV surge protection for reliable performance over a long product lifetime and meet the safety standards required for operator protection.

INDUSTRIAL MAGNETOMETER
Electronics crafted for industrial applications require a level of reliability beyond what’s acceptable in other applications. For its part, STMicroelectronics (ST) in July introduced its IIS2MDC magnetometer and ISM303DAC eCompass devices that enable both reliable, low-power tamper detection for smart meters and precision motion and distance sensing in applications like industrial automation and robotics (Figure 5).

FIGURE 5 – The IIS2MDC magnetometer and ISM303DAC eCompass devices enable both reliable, low-power tamper detection for smart meters and precision motion and distance sensing in applications like industrial automation and robotics.

With industrial-grade longevity that assures availability for 10 years, both sensors contain an AMR (Anisotropic Magneto-Resistive) magnetometer with high dynamic range of ±50 Gauss, which meets best-in-class benchmarks for resolution and low power consumption. Each also features an integrated temperature sensor, and provides a 16-bit digital output via a built-in I2C/SPI serial interface.

The ISM303DAC’s additional integrated low-noise 3-axis accelerometer with user-selectable full-scale range up to ±16g enables dual-mode magnetic/physical tamper detection. It also serves applications such as antenna pointing, positioning and navigation, robot guidance and general industrial motion tracking or distance sensing. The magnetic and accelerometer blocks can be powered down independently to maximize energy savings.

Both devices can be configured to generate an interrupt signal for magnetic field detection and automatically compensate for hard-iron offsets provided from the higher application layer. Additionally, the ISM303DAC can also generate interrupts upon recognition of freefall events, tap and double-tap, activity or inactivity, 6D-orientation thresholds and wake-up events. A built-in FIFO stores accelerometer data to minimize main-processor intervention and, as a result, reduce system power consumption.

Development support includes drivers for both sensors, and software examples including tilt-compensated electronic compass, dynamic magnetometer calibration and 6-axis or 9-axis sensor fusion. The STEVAL-MKI185V1 adapter board for the IIS2MDC and STEVAL-MKI184V1 for the ISM303DAC are also available, ready to plug into a standard DIL24 socket on a motherboard such as the STEVAL-MKI109V3 professional MEMS board to assist development using ST’s Unico GUI. The IIS2MDC and ISM303DAC are available in the leadless 2 mm x 2 mm x 0.7 mm LGA-12 package.

BUCK-BOOST CONTROLLERS
Not all industrial systems have the luxury of being connected to a power main. Industrial battery-powered applications have their own particular needs. With that in mind, Renesas Electronics last month (October) announced a new family of bidirectional four-switch synchronous buck-boost controllers. According to the company, the ISL81601 and ISL81401 are the industry’s only true bidirectional controllers that sense peak current at both ends and provide cycle-by-cycle current limit in both directions while in buck or boost mode (Figure 6).

FIGURE 6 – The ISL81601 and ISL81401 are bidirectional four-switch synchronous buck-boost controllers. They have bidirectional peak current sensing capability that eliminates complex external circuitry required for charging and discharging a battery to supply power to the loads.

The controllers generate point-of-load (POL) and voltage rail conversions with peak efficiency up to 99%. The ISL81601 has a wide input range of 4.5 V to 60 V and produces a 0.8 V to 6 0 V output to support most industrial batteries: 12 V, 24 V, 36 V and 48 V. Also available is the ISL81401, a 4.5 V to 40 V input and 0.8 V to 40 V output version, and its unidirectional counterpart, the ISL81401A. The new controllers are well suited for DC power backup and battery-powered medical, industrial and telecommunication systems.

The ISL81601 and ISL81401’s bidirectional peak current sensing capability eliminates complex external circuitry required for charging and discharging a battery to supply power to the loads. Their proprietary algorithm provides smooth mode transitions between buck, boost and buck-boost, while reducing low frequency ripple at VOUT, ensuring minimal disturbances during line or load transients. The algorithm also ensures predictable ripple voltage under all conditions. The addition of multilayer overcurrent protection and a precision control algorithm delivers constant current down to 0.1 V at VOUT for reliable operation. Designers can easily expand system power by paralleling an unlimited number of controllers. The ISL81601 and ISL81401 operate two switches at a time to minimize power loss and achieve higher efficiency.

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The ISL81601 and ISL81401/A can be combined with a Renesas RL78 MCU, or other MCUs, to program the voltages, battery charge/discharge function and on-the-fly bidirectional power flow. Designers can also use the PowerCompass tool to help them quickly identify other power supply parts that match their specific system requirements. Multiple power rails can be set up and designers can perform high-level system analysis and generate custom reference design files in minutes.

MAGNETIC ANGLE SENSORS
The evolution of sensor integration has resulted in very powerful single-chip sensor solutions. The technology advancement has impacted a variety of markets, industrial automation included. In June, Infineon Technologies launched its first magnetic sensors based on Tunnel Magnetoresistance (TMR) technology. According to the company, that made them the first sensor manufacturer to offer magnetic sensors based on all four magnetic technologies: HALL, GMR, AMR and TMR. The XENSIV TLE5501 angle sensor family products are fast analog TMR-based angle sensors dedicated to automotive applications. Their fields of use range from steering angle applications with the highest functional safety requirements to motors for wipers, pumps and actuators and electric motors in general. They are also ready to be used in industrial and consumer applications like robotics or gimbals.

The TMR technology offers a high sensing sensitivity that comes with a high output voltage realizing output signals of up to a 0.37 V/V voltage gain for all XENSIV TLE5501 products (Figure  7). Unlike other technologies, a TMR-based sensor can be connected directly to the MCU without any further amplification, thus saving costs for the customer. Furthermore, TMR shows a very low temperature drift reducing external calibration and compensation efforts. In addition, TMR technology is well known for its low current consumption, which is as low as 2  mA for the XENSIV TLE5501 family.

FIGURE 7 – TMR technology offers a high sensing sensitivity that comes with a high output voltage realizing output signals of up to 0.37 V/V for all XENSIV TLE5501 magnetic angle sensor products.

The new sensor family will be available at two different qualification levels. The TLE5501 E0001 is qualified according to AEC Q100. This version is pin-compatible to the established Infineon TLE5009 but can enable cheaper systems as no additional amplifier is necessary. The other version, the TLE5501 E0002, offers ISO26262-compliant development, achieving ASIL D level with just one single chip. It incorporates decoupled bridges for redundant external angle calculation and offers the highest diagnostic coverage demanded by functional safety regulations. 

Analog and mixed-signal ICs play important roles in industrial automation and process control applications. These systems applications depend heavily on innovations in amplifiers, data converters, sensor solutions and more.

RESOURCES
Analog Devices | www.analog.com
Infineon Technologies | www.infineon.com
Maxim Integrated | www.maximintegrated.com
Renesas Electronics | www.renesas.com
STMicroelectronics | www.st.com
Texas Instruments | www.ti.com

PUBLISHED IN CIRCUIT CELLAR MAGAZINE • NOVEMBER 2018 #340 – Get a PDF of the issue

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Editor-in-Chief at Circuit Cellar | Website | + posts

Jeff Child has more than 28 years of experience in the technology magazine business—including editing and writing technical content, and engaging in all aspects of magazine leadership and production. He joined the Circuit Cellar after serving as Editor-in-Chief of COTS Journal for over 10 years. Over his career Jeff held senior editorial positions at several of leading electronic engineering publications, including EE Times and Electronic Design and RTC Magazine. Before entering the world of technology journalism, Jeff worked as a design engineer in the data acquisition market.

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Analog IC Advances Target Industrial Automation

by Jeff Child time to read: 12 min