Research & Design Hub Tech Trends

Analog ICs Feed Needs of Industrial Systems

Written by Jeff Child

Advances for Automation

Industrial automation and process control applications rely heavily on a variety of analog ICs to ensure smooth, reliable system operations. Chip vendors are responding with new solutions across the spectrum of analog ICs, including amplifiers, data converters, motor drivers and more.

As factories migrate to ever more automated and “smart” operations, system developers are hungry for new advances in a variety of analog IC product areas. Advances span everything from data converters to comparators to motor drivers. These devices must meet the particular performance levels for industrial designs while meeting the harsh environmental demands of the factory floor.

To keep pace with the needs of industrial system developers, over the past 12 months analog ICs vendors have continued to roll out new chips designed to meet a variety of industrial design needs, including factory robotics, instrumentation systems and control automation systems. Products include both ICs specifically designed for the industrial market and those for which industrial is one among a range of other applications targeted.

ENERGY-EFFICIENT DRIVER
Exemplifying these trends, in September, Analog Devices (ADI) announced the ADuM4122, an isolated, dual-drive strength output driver that uses iCoupler technology. It’s designed to empower designers to harness the benefits of higher efficiency power switch technologies. Electric motor-driven systems account for 40% of global electricity consumption, according to the International Energy Agency, and improvements in motor efficiency can have wide-reaching economic and environmental benefits.

With the increased adoption of industrial automation and IoT within smart factories, there is a growing demand for intelligent technology and features within systems to ensure maximum efficiency, says ADI. The ADuM4122 is claimed to be the first simple solution that accomplishes this by controlling how fast or slow a MOSFET or IGBT turns on or off by user command, on the fly, thereby controlling motor currents (Figure 1).

FIGURE 1 – The ADuM4122 is a simple dual-drive strength output driver that efficiently toggles between two slew rates controlled by a digital signal. The device can control how fast or slow a MOSFET or IGBT turns on or off by user command, on the fly, thereby controlling motor currents.

The new ADuM4122 is a simple dual-drive strength output driver that efficiently toggles between two slew rates controlled by a digital signal. Smaller than existing discrete or complex integrated solutions that have 20 or more pins, the ADuM4122 features only eight pins and works in a variety of operating conditions. The ADuM4122 further improves system capabilities with high common-mode transient immunity and low propagation delay for high performance applications such as motion control, robotics and energy.

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HIGH-ACCURACY ADCs
Analog-to-digital converter (ADC) technology continues to be critical in industrial applications, particularly for precision instrumentation system designs. With that in mind, in June, Microchip Technology rolled out a new family of compact ADCs that offer high programmable data rates of up to 153.6 Ksps. According to the company, the 24-bit MCP356x and 16-bit MCP346x delta-sigma ADC families offer faster programmable data rates than similar devices on the market while providing high accuracy and lower noise performance (Figure 2). Available in a tiny 3 mm x 3 mm UQFN-20 package, these integrated ADCs are designed to meet the increasing demand for small packaging in space-constrained applications such as portable instrumentation devices.

FIGURE 2 – The 24-bit MCP356x and 16-bit MCP346x delta-sigma ADC families offer high programmable data rates of up to 153.6 Ksps. Available in a tiny 3 mm x 3 mm UQFN-20 package, these integrated ADCs are designed to meet the increasing demand for small packaging in space-constrained applications.

Most high-resolution delta-sigma ADCs on the market have slower programmable data rates of a few Ksps, says Microchip. The MCP356x and MCP346x families offer a much faster data rate, making the devices ideal for a variety of precision applications that require different data speeds, including industrial process control, factory automation and sensor transducers and transmitters. The ADCs also offer integrated features to eliminate the need for external components and reduce the overall cost of a system, including an internal oscillator, temperature sensor and burnout current source.

The new families provide 24-bit or 16-bit resolution, two/four/eight single-ended or one/two/four differential channel options, allowing developers to choose the most suitable ADC for their designs. For development tools, Microchip provides the MCP3564 ADC evaluation kit (ADM00583). The kit includes a MCP3564 ADC Evaluation Board for PIC32 MCUs (ADM00583), a PIC32MX795F512L PIM (processor plug-in module) and a USB cable.

AMPLIFIERS AND COMPARATORS
Current-sense amplifiers and comparators are among the list of analog ICs important to many industrial electronic systems. Addressing those needs, in June, Texas Instruments (TI) introduced what it claims is the industry’s smallest current-sense amplifier in a leaded package and the smallest, most accurate comparators with an internal 1.2-V or 0.2-V reference. Offered in industry-leading package options, the INA185 current-sense amplifier, and open-drain TLV4021 and push-pull TLV4041 comparators enable engineers to design smaller, simpler and more integrated systems while maintaining high performance. In addition, pairing the amplifier with one of the comparators produces the smallest, highest performing overcurrent detection solution in the industry, says TI. Figure 3 shows the INA185 in a typical circuit.

FIGURE 3 – Shown here in a typical circuit, the INA185 current-sense amplifier features a 55-µV input offset that enables higher precision measurements at low currents. The INA185 enables the use of lower-value shunt resistors to cut system power consumption. Its 350-kHz bandwidth and 2-V/µS slew rate enable phase-current reproduction to enhance motor efficiency and save system power.

These new devices are optimized for a variety of industrial and communications applications and well as personal electronics. With a small-outline transistor (SOT)-563 package measuring 1.6 mm by 1.6 mm (2.5 mm2), the amplifier is 40% smaller than the closest competitive leaded packages. Featuring a 55-µV input offset that enables higher precision measurements at low currents, the INA185 enables the use of lower-value shunt resistors to cut system power consumption. Additionally, its 350 kHz bandwidth and 2-V/µS slew rate enable phase-current reproduction to enhance motor efficiency and save system power.

The precisely matched resistive gain network in the amplifier enables a maximum gain error as low as 0.2%, which contributes to robust performance over temperature and process variations. The device’s typical response time of 2 µs enables fast fault detection to prevent system damage. System designers can add functionality in the same form factor and enable high-performance design with the TLV4021 and TLV4041 comparators. Available in an ultra-small die-size ball-grid array (DSBGA) 0.73 mm by 0.73 mm package, the comparators’ integrated voltage reference saves board space while supporting precise voltage monitoring, which optimizes system performance.

The comparators can monitor voltages as low as the 0.2-V internal reference, and feature a high threshold accuracy of 1% across a full temperature range from -40°C to +125°C. Low 2.5-µA quiescent current delivers extended battery life for smart, connected devices. Fast propagation delay as low as 450 ns reduces latency, enabling power-conscious systems to monitor signals and respond quickly to fault conditions.

When using both the INA185 and the TLV4021 or TLV4041, engineers can shrink their total footprint to enable smaller systems. In combination, these devices produce the smallest, highest-performing overcurrent detection solution–15% smaller and 50 times faster than competitive devices, says TI. Pairing the amplifier with one of the comparators to support overcurrent detection on rails as high as 26 V delivers more headroom to better manage current spikes.

Production quantities of the INA185 are now available through the TI store and authorized distributors in a SOT-563 package, measuring 1.6 mm by 1.6 mm. Production quantities of the push-pull TLV4041 and preproduction samples of the open-drain TLV4021 comparators are now available through the TI store and authorized distributors in an ultra-small DSBGA package, measuring 0.73 mm by 0.73 mm.

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SMART SHUT DOWN
The ability to reliably shut down factory equipment in industrial applications is important for safety as well as ensuring smooth operations. Along those lines, in July, STMicroelectronics (ST) announced the STDRIVE601, a 3-phase gate driver for 600 V N-channel power MOSFETs and IGBTs. It was designed to provide state-of-the-art ruggedness against negative voltage spikes down to -100 V and responds to logic inputs in a class-leading 85 ns.

Featuring smart-shutdown circuitry for fast-acting protection, the STDRIVE601 turns off the gate-driver outputs immediately after detecting overload or short-circuit, for a period determined using an external capacitor and resistor. Designers can set the required duration, using large C-R values if needed, without affecting the shutdown reaction time. An active-low fault indicator pin is provided. The STDRIVE601 replaces three half-bridge drivers to ease PCB layout and optimize the performance of 3-phase motor drives for equipment such as home appliances, industrial sewing machines and industrial drives and fans.

All outputs can sink 350 mA and source 200 mA, with gate-driving voltage range of 9 V to 20 V, for driving N-channel power MOSFETs or IGBTs. Matched delays between the low-side and high-side sections eliminate cycle distortion and allow high-frequency operation, while interlocking and deadtime insertion are featured to prevent cross conduction.

Fabricated in ST’s BCD6S offline process, the STDRIVE601 operates from a logic supply voltage up to 21 V and high-side bootstrap voltage up to 600 V. Bootstrap diodes are integrated, saving the bill of materials, and under-voltage lockout (UVLO) on each of the low-side and high-side driving sections prevents the power switches operating in low-efficiency or dangerous conditions. An evaluation board, EVALSTDRIVE601, is available to help users explore the features of the STDRIVE601 and quickly get first prototypes up and running.

INDUSTRIAL PHOTOCOUPLERS
While photocouplers are used in a variety of applications, they must meet special requirements to be used in the harsh environment of a factory setting. Offering a solution, in July, Renesas Electronics announced three new 15 Mbps photocouplers designed to withstand the harsh operating environments of industrial and factory automation equipment. The trend toward higher voltage, compact systems is driving stricter international safety standards and eco-friendly solutions that require smaller ICs with lower power consumption. The RV1S9x60A family meets this need with low threshold input current (IFHL) ratings: the RV1S9160A (SO5) operates at 2.0 mA, the RV1S9060A (LSO5) at 2.2 mA, and the RV1S9960A (LSDIP8) at 3.8 mA (Figure 4).

FIGURE 4 – These three 15 Mbps photocouplers are designed to withstand the harsh operating environments of industrial and factory automation equipment. The RV1S9x60A family offers low threshold input current (IFHL) ratings: the RV1S9160A (SO5) operates at 2.0 mA, the RV1S9060A (LSO5) at 2.2 mA, and the RV1S9960A (LSDIP8) at 3.8 mA.

Lower power consumption allows the RV1S9x60A photocouplers to meaningfully suppress power supply heat generation. And high temperature operation up to 125°C enables board space savings by mounting the photocoupler near the IGBT or MOSFET power device. The devices are targeted at DC to AC power inverters, AC servo motors, programmable logic controllers (PLCs), robotic arms, solar and wind input power conditioners, and battery management systems for energy storage and charging.

The RV1S9x60A photocouplers feature high common mode rejection (noise tolerance) up to 50 kV/µs (min) to protect MCUs and other I/O logic circuits from high voltage spikes while transferring high-speed signals. The RV1S9x60A family also offers a variety of packages with the smallest footprint for each reinforced isolation (up to 690 VRMS), and minimum creepage distances of 4.2 mm to 14.5 mm to ensure safe operation.

The RV1S9160A, RV1S9060A and RV1S9960A photocouplers provide low voltage power supply operation of 2.7 V to 5.5 V. Isolation voltages for the devices are as follows: 3750 VRMS (RV1S9160A), 5000 VRMS (RV1S9060A) and 7500 VRMS (RV1S9960A). The devices operate in high temperatures from -40°C to +125°C (RV1S9160A and RV1S9060A), and from -40°C to +110°C (RV1S9960A). Supply current of 2.0 mA maximum, while pulse width distortion at is a low 20 ns maximum. Propagation delay for the devices is of 60 ns max with propagation delay skew of 25 ns max.

POWER FACTOR CONTROLLER
For industrial equipment to operate efficiently, system designers need power-factor control suited today’s digital power system configurations. With that in mind, in August, STMicroelectronics announced the STNRGPF12, a dual-channel interleaved boost-PFC controller that aims to blend the flexibility of digital power with the responsiveness of analog algorithms. The device can be easily configured and optimized using the ST’s eDesignSuite software. Suited to applications over 600 W, the STNRGPF12 enhances efficiency and reliability in equipment as diverse as industrial motor controls, charging stations, uninterruptable power supplies, 4G and 5G base stations, welding machines, telecom switches, home appliances and data-center power supplies.

The STNRGPF12 operates in continuous-conduction mode (CCM) at fixed frequency with average-current-mode control (Figure 5). The best of both digital and analog worlds meets in the STNRGPF12’s inner and outer control loops. The inner current loop utilizes a hardware analog Proportional-Integral (PI) compensator, while the outer voltage loop is performed by a digital PI controller with fast dynamic response. This enables the STNRGPF12 to manage cascaded control of the voltage and current loops to regulate the output voltage by acting on the total average inductor current.

FIGURE 5 – The STNRGPF12 is a dual-channel interleaved boost-PFC controller designed to blend the flexibility of digital power with the responsiveness of analog algorithms. Suited to applications over 600 W, the STNRGPF12 enhances efficiency and reliability in equipment such as industrial motor controls.

Integrated features include digital inrush-current limiting, which leverages silicon-controlled rectifiers (SCR) in the high-side switching circuitry to facilitate soft-start management and enhance system robustness. The STNRGPF12 also supports load feed-forward, current balancing, phase shedding, and fan control. An integrated UART allows access to non-volatile memory for user configuration of PFC parameters to meet specific application needs and permits monitoring of parameters in the field. In support of the STNRGPF12, ST provides an extensive ecosystem that includes the STEVAL-IPFC12V1 dual-channel 2 kW interleaved PFC reference design, as well as the configuration software. 

RESOURCES
Analog Devices | www.analog.com
Microchip Technology | www.microchip.com
Renesas Electronics | www.renesas.com
STMicroelectronics | www.st.com
Texas Instruments | www.ti.com

PUBLISHED IN CIRCUIT CELLAR MAGAZINE• NOVEMBER 2019 #352 – 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.