Category Archives: IC’s

24-Bit Quad-Channel ADC

Analog Devices is offering a 24-bit Quad-Channel ADC, the AD7134, a low noise, precision type, simultaneous sampling Analog to Digital Converter that while offering exceptional functionality and performance, is also easy to use.

The AD7134 operates on the continuous-time sigma-delta or CTSD modulation scheme. This helps to remove the traditional requirement of a sampling switched capacitor circuitry preceding the sigma-delta modulator—simplifying the input driving requirement for the ADC. The device also has inherent antialiasing capability, arising out of the CTSD architecture rejecting signals around the aliasing frequency band of the ADC. Therefore, this ADC does not need the regular complex antialiasing filter.

The four independent converter channels of the AD7134 operate in parallel, and each of them has its own CTSD modulator along with a digital filtering and decimation path. Therefore, the user can sample four separate analog signals, each with a maximum input bandwidth of 391.5 kHz. The four signal measurements can also achieve tight phase matching among themselves. Therefore, the AD7134 can offer a high density of multichannel data acquisition in a small form factor, because of its simplified requirement of analog front-end, and a high level of channel integration.

ADCs normally require a complicated signal chain and an analog front-end circuitry that introduces distortion, mismatch, error, and noise at the ADC output. As the AD7134 simplifies the signal chain requirements, it also improves the system level performance of the device.

Offering excellent AC and DC performance, the bandwidth for each ADC channel of the device ranges from 0 to 391.5 kHz. Therefore, the AD7134 is an ideal choice for acquiring data with universal precision, and capable of supporting a variety of sensor types ranging from shock and vibration to pressure and temperature.

With several configuration options and features, the AD7134 offers the user the flexibility of achieving an optimal balance between power, accuracy, noise, and bandwidth for specific applications.

Analog Devices has integrated an asynchronous sample rate converter or ASRC with their AD7134 for precise control of the decimation ratio. This, in turn, allows the AD7134 to support a wide range of output data rates or ODR frequencies ranging from 0.01 kSPS to 1496 kSPS as the ODR uses interpolation and resampling techniques. Furthermore, as the adjustment resolution between the ODRs is less than 0.01 SPS, the user can vary the sampling speed granularly to achieve coherent sampling.

The user can also use multiple AD7134 devices with synchronous sampling between them using a single system clock, and this is because of the ASRC slave mode operation. The slave mode simplifies the requirement of clock distribution for a data acquisition system of medium bandwidth as each ADC no longer requires routing of low jitter, high-frequency master clock from the digital back end.

The AD1734 can perform on-board averaging between two or four of its input channels. This results in improving the dynamic range while the device maintains its bandwidth. Combining two channels improves the results by about 3 dB, while combining all the four channels offers an improvement of nearly 6 dB.

Why Low Dropout Regulators?

In this era of high-efficiency switching power supplies and voltage regulators, low dropout (LDO) regulators seem almost out of place. Contrary to popular belief, low dropout regulators are small components, simple to use, and cost-effective for obtaining an output of regulated voltage from an input of higher voltage.

For system designers, low dropout regulators offer a simple method of obtaining a voltage from a source that is very close to the output voltage. This is one major reason designers use LDO regulators widely. The second reason is LDO regulators are analog devices, and unlike switching regulators, introduce very low noise into the system.

Small LDO regulator devices such as those from Diodes Incorporated offer a variety of features such as high-power supply rejection ratio, ultra-low quiescent current, wide input voltage handling capability, physically small footprint, and high output current supply capability.

Keeping in line with other SMT components, manufacturers are making LDO regulators in smaller form factors, enabling designers to use PCB space more effectively. Designers can make better use of the newer families of LDO regulators in highly dense PCBs as these components are of very small size, and occupy the minimum space, while they offer the same high-quality performance.

Not all power supply sources offer clean and regulated outputs. LDO regulators help filter out most of the noise from unregulated power sources with their high-power supply rejection ratio specifications. By rejecting the noise from the power source, LDO regulators provide noiseless and spike-free DC power to ensure the system operates reliably.

Many systems do not require continuous power. In remote areas, where it is difficult to deliver power, engineers rely on batteries to power their equipment. LDO regulators with ultra-low quiescent current consumption are a boon, as they consume the minimum amount of power when the system is idle, resulting in a significant increase in the life of the battery.

LDO regulators can handle a wide range of input voltages, in some cases, up to as high as 40 VDC. In multi-voltage systems, which are now common-place, such LDO regulators are very cost-effective, and they make the design more robust and reliable.

Sensors and related electronics work better with clean power supplies. Noise from switching regulators can limit the sensitivity of sensors drastically, resulting in reduced coverage or misleading measurements. LDO regulators supplying clean and efficient power with high current output allow using components for sensitive measurements, without the introduction of ripple and noise. Even with their high current output, LDO regulators work with voltage differentials as low as 350 mVDC.

Automotive applications require high-temperature reliability, and LDO regulators are available that cover a wide temperature range of -40 ºC to +125 ºC. This is a necessary feature in an automobile, as many applications must work concurrently to keep the vehicle operational.

The new family of LDO regulators are ideal for portable and small consumer devices, such as smartwatches, smartphones, wearables, wireless earphones, smart homes, smart offices, and different sensor applications. The industry uses these LDO regulators for other applications such as healthcare devices, smart meters, and other devices powered by batteries.

LTM2893 μModule isolator for ADCs

Analog to digital converters (ADCs) need to float to the common mode of the input signal to absorb the harsh voltage conditions and transients. The best way to do this is to place an isolation barrier between the ADC and the external signal. Even applications that perform under moderate conditions can benefit from the presence of an isolator. The LTM2893 from Linear Technology provides such isolation, improving on system safety, especially when reading from high-resolution successive approximation register type of ADCs.

Ideally, the isolator for an ADC should be near invisible. Its function would be to manage the control and data signals, maximizing the sampling rate, and minimizing the effects of jitter on the performance of signal to noise ratio. The LTM2893 μModule isolator from Linear Technology meets all the above criteria, achieving these for ADCs with SPI interfaces, offers a 1 Msps range, while supporting a 6K Vrms isolation rating.

Options that are more traditional exist, but provide limited functionality, especially when reading data from high-resolution successive approximation register (SAR) ADCs. Most traditional high speed digital isolators work maximum up to 25 MHz, with a few special devices reaching 40 MHz On the other hand, the LTM2893 can easily read data samples at rates up to 100 MHz. Additionally, it is flexible enough to be able to handle multiple ADCs. This effectively solves timing issues and other limitations of the standard digital isolator interfacing that SAR ADCs face.

Test and process equipment need isolation so that their inputs are not damaged if accidentally misconnected or from overvoltage events. Usually, engineers use an isolator as a high voltage level shifter for extending the common mode range thereby reducing the ground noise. The LTM2893 is intelligent enough to ignore transients events of the common mode type up to 50K V/μs, as this provides a low-capacitance isolation barrier along with fully differential data communication.

When dedicated SPI isolators and other general-purpose digital isolators isolate ADCs, they use multiple digital isolators for supporting signals such as busy status or conversion start signals. In addition, they offer a 3- or 4-wire SPI port. They also suffer from signal propagation delays, as the isolated SPI port must wait for the return of the acknowledgement signal before the next data latching can occur. Adding all the propagation and the response delays from the ADC SPI port, a single read may suffer a delay of about 35 ns. Therefore, although the initially rating of a digital isolator may be at 150 Mbps, in reality, the delays reduce the effective frequency to 25 MHz or even less.

Linear Technology has provided the LTM2893 with a dedicated master SPI engine on its isolated side, and a dedicated slave engine and a buffer on the logic side. The master SPI engine of the LTM2893 monitors the status signals from the ADC, fetching the data as soon as its BUSY signal goes low. There is no interaction with the logic side once the conversion has started.

The buffer register on the slave SPI engine on the logic side receives data from the isolated side via the isolated barrier. The two sides therefore, operate independently of each other.

What are Ball Grid Arrays?

Initially, surface mount devices, especially ICs, came as perimeter-only packages, with pins for soldering placed along the edge of the device. As ICs became more complex, they needed more pins for external interfacing, which made the packages larger. Manufacturers soon realized there was a large unused real estate that lay just under the package. Therefore, they made the ball grid array (BGA) packaging, which, in place of pins, had solder balls aligned in a grid under the device. Soldering BGAs involves melting these solder balls onto pads on the PCB.

Using BGAs leaves a considerably larger area free on the PCB. Compared to mounting a package with pins on its perimeter, BGAs offer better thermal and electrical properties, and this has made the format popular, following the continued miniaturization of electronics.

Since their introduction, although their basic concept has remained the same, BGAs have changed in dimension and now come with far smaller pitches and smaller outlines. There are varieties as well, with some packages having connections only on the periphery and none at the center, while others have the connections distributed evenly across the bottom of the package.

For simpler BGAs, routing traces on the PCB is simple as the balls are placed well apart or there is space in the middle of the device. However, with increasing pin counts and decreasing pitches, routing between the pins becomes more difficult, resulting in increasing the layers of the board, thereby increasing the cost and reliability concerns.

As BGAs become increasingly more complex, designers have to depend on vias to connect the BGA with the rest of the circuitry on the PCB. Vias are small holes drilled through the multilayer PCB and plated with copper to provide connection between pads and traces on different layers. Some vias are through-hole types, meaning they start and end on the two extreme layers of the PCB, and may connect to other layers in between. Other vias can be blind types, starting from one of the outermost layers and ending on an internal layer, possibly connecting other layers in between. Blind vias are not visible on the PCB surface as they start and end at different internal layers, and may connect other internal layers as well. However, all the above require great precision while manufacturing, and are expensive processes.

Ordinarily, PCB designers prefer not to use vias on a pad, as during soldering, vias can wick solder from the pads leaving the joint in a dry and unsoldered state. However, with BGA pitches getting increasingly smaller, designers do not have much choice, but tenting is offering a way out. Tenting allows filling the via hole with an insulating material and covering the top with a layer of copper, thereby preventing wicking.

As the BGA pins lie in between the device body and the PCB, traditional soldering methods such as hand soldering and wave soldering are no longer useful, and assemblers rely on infrared heating or reflow ovens to solder BGAs to a PCB. This requires a pick-and-place machine placing the BGA package precisely on the pads and uniformly heating the area to form the actual connections.

Choosing a Regulator – Switching or LDO

Unlike AC circuits where a simple transformer can change the incoming voltage to a different level, DC circuits need an active device to change the voltage to the desired level. In general, there are two types of circuits to do this—switching and linear. Switching regulators are highly efficient and work on buck, boost, or buck-boost technology to change the voltage level. On the other hand, linear regulators such as LDOs are ideal for powering very low power devices or applications where the difference between the input and output voltages is small. Compared to switching regulators, linear regulators generate lower noise, are simple and cheap, but inefficient.

Linear Regulators (Low-Dropout Regulators)

Using linear circuits and non-linear techniques, linear regulators regulate the voltage output from the input supply. The resistance of the regulator varies according to the load and this creates a constant output voltage.

Irrespective of their make and design, all linear regulators must have their input voltage at least some minimum amount higher than the desired output voltage. Engineers call this minimum amount as the dropout voltage. An LDO regulator or low-dropout regulator is a DC linear regulator that is able to regulate the output voltage even for very low differences between the input and output voltages.

Therefore, applications that need an input voltage very close to the supply voltage and consume low power are ideal for linear regulators. As the product of the load current and difference of the input and output voltages governs the power dissipated by a linear regulator, a smaller difference means the regulator can handle higher power or allow a higher load current.

Although the linear regulators or low-dropout regulators offer a simple and cheap solution, these devices are notoriously inefficient as they dissipate heat based on the difference between the input voltage and the regulated output voltage. Most low-dropout regulators are low-current devices, offering well-regulate outputs, and require very few external components. They usually come in small packages, have fast transient response, and are highly accurate.

Switching Regulators

Most solutions for power management today require low power consumption under various load conditions, ability to operate in small spaces, offer high reliability, and the capability of withstanding wide input voltages. Therefore, a broad range of applications is moving towards highly efficient, wide input, low quiescent current switching regulators.

Switching regulators work by switching a series element on and off very rapidly. The series element can be either synchronous or non-synchronous FET switches. Usually, an associated inductor stores the input energy temporarily, and releases the energy subsequently to the output circuit at a different voltage level. The duty cycle of the switch determines the amount of charge transferred to the load.

Switching regulators operate efficiently, as their switching element dissipates almost no power, because the element is either switched off or fully conducting. Unlike linear regulators, switching regulators can generate output voltages higher than the input voltage or of the opposite polarity.

Therefore, switching regulators offer wide input and output voltage ranges, integrated series elements, pin-to-pin compatible parts, internal compensation, and light load efficiency modes, while being simple and easy to use.

What is BiCMOS Technology?

CMOS and Bipolar are two of the pioneering technologies of the electronics field. Components fabricated with the CMOS technology dissipate lower power, have smaller noise margins, and are physically smaller. On the other hand, components fabricated with the bipolar technology operate at higher speeds, switch faster, and offer good noise performance. By combining the two, scientists have created the BiCMOS technology that offers a combination of advantages from both processes. For instance, BiCMOS offers higher speeds compared to that of CMOS, and lower power dissipation compared to that of bipolar. However, the penalty comes in the form of added process complexity and it adds to the cost. Both CMOS and bipolar issues need optimization of impurities, and this increase in process complexity results in higher costs compared to that of conventional CMOS.

Scientists have worked out the optimum approach to fabricate high performance BiCMOS devices. They have found it best to start with a baseline CMOS process and add the bipolar process steps. This produces an optimum BiCMOS process flow, emphasizes reliability and process simplicity, while maintaining compatibility with the CMOS technology.

There are several advantages of the BiCMOS technology. The higher impedance of the CMOS circuitry facilitates the analog amplifier input design, while bipolar transistors define the rest. BiCMOS can stand wide temperature variations and process variations, which make this technology more economical. BiCMOS devices can source and sink much higher load currents because of the MOS part, while it handles higher speeds because of the bipolar part. BiCMOS can drive high capacitance loads with lower cycle times. As the source and drain can be interchanged, BiCMOS demonstrates bidirectional capabilities, which makes it suitable for IO intensive applications.

BiCMOS technology has its drawbacks as well. The fabrication complexity is higher because both CMOS and bipolar technologies are involved. This increases the cost of fabrication also. However, as BiCMOS devices have higher density, the amount of lithography required is lower.

BiCMOS technology is versatile for several applications. Its higher speed makes it suitable for AND functions of high density. It easily replaces devices formed with earlier technologies such as CMOS, ECL, and bipolar, for instance, in some cases BiCMOS has higher speed performance compared to that from bipolar. A single chip with the BiCMOS technology can span the analog-digital boundary. Their high impedance input makes BiCMOS a very good candidate for applications such as sample and hold, adders, mixers, ADCs, DACs.

STMicroelectronics integrates RF, analog, and digital parts on a single chip. Their BiCMOS SiGe technology reduces the number of external components drastically, while optimizing the power consumed by the chip. The advantages of the integration are significant as earlier, only more expensive technologies were able to achieve this level of performance.

As ST explains, the Heterojunction Bipolar Transistor (HBT) of BiCMOS has a much higher cut-off frequency compared to bulk CMOS. To attain such frequencies, the bulk CMOS designs need to use far smaller process nodes. This forces design compromises leading to overall lower performances and higher costs. Therefore, the BiCMOS technology offers a better cost profile compared to other alternatives.

What Are Super-Junction MOSFETs?

Switching power-conversion systems such as switching power supplies and power factor controllers increasingly demand higher energy efficiencies. For such energy-conscious designers, super-junction MOSFETs are a favored solution, as the technology allows smaller die sizes when considering key parameters such as on-resistance. This leads to an increase in current density while enabling designers to reduce circuit size. With increasing market adoption of this new technology goes up, other challenges are coming to the fore, mainly the requirement for improved noise performance.

High-end power supplies for equipment such as LED lighting, LCD TVs, notebook power adapters, medical power supplies, and tablet power supplies require reduced electromagnetic noise emission. Designers prefer using resonant switching topologies such as the LLC converter with zero-voltage switching, as these have inherently low electromagnetic emissions. Super-junction transistors in the primary side switching in an LLC circuit helps designers achieve a compact and energy-efficient power supply.

Compared to conventional planar silicon MOSFETs, the super-junction MOSFET has significantly lower conduction loss for a give die size. Additionally, architecture of the latter device allows lower gate charges and capacitances, leading to lower switching losses compared to conventional silicon transistors.

Fabricators used a multi-epitaxial process for structuring the early super-junction devices. They doped the N-region richly allowing a much lower on-resistance compared to conventional planar transistors. They adapted the P-type region bounding the N-channel to achieve the desired breakdown voltage.

The multi-epitaxial processes resulted in the N- and P-type structures being dimensionally larger than ideal and led to an associated impact on overall device size. The nature of the multi-epitaxial fabrication also restricted engineering the N-region to minimize on-resistance. Therefore, fabricators now use single-epitaxial fabrication processes such as deep trench filling to optimize the aspect ratios of N- and P-regions to minimize the on-resistance while also reducing the size of the MOSFET.

For instance, the single epitaxial fabrication process allows DTMOS IV family of Toshiba’s fourth-generation super-junction MOSFETs to achieve a 27% reduction in device pitch, while also reducing the on-resistance by 30% for each die area. Similarly, Toshiba’s DTMOS V, based on deep trench process, has further improvements at the cell structure level.

Thanks to the single-epitaxial process, the super-junction MOSFETs can deliver more stable performance when faced with temperature changes. Power converters with conventional MOSFETs are noted for reduced efficiencies at higher operating temperatures, which the super-junction MOSFETs are able to counter. For instance, super-junction MOSFETs show a12% lower on-resistance at 150°C.

Power converters using the fifth-generation super-junction DTMOS V devices can now deliver low-noise performance along with superior switching performance. A modified gate structure and patterning helps to achieve this, resulting in an increase in the reverse transfer capacitance between the gate and drain of the device.

Accurate Power Monitoring with LTC2992

Linear Technology Corporation, now a part of Analog Devices, Inc., has recently placed on the market a power monitoring IC, LTC2992, which offers a wide-range, dual monitoring system for current, voltage, and power for 0-100 VDC rails. The IC is self-contained and does not need additional circuitry for functioning.

Users get a variety of options for operating the LTC2992. For instance, they can derive power from a 3-100 VDC monitored supply, or from a 2.7-100 VDC secondary supply, or from the shunt regulator on-board. Therefore, when monitoring the 0-100 VDC rail, the designer does not have to provide a separate buck regulator, a shunt regulator, or an inefficient resistive divider.

Within the LTC2992 are a multiplier and three Analog to Digital Converters (ADCs) of the delta-sigma type. Two of the ADCs provide measurements for current in each supply, while the third ADC measures voltage in 8- or 12-bit resolution and power in 24-bit resolution. The wide operating range of the LTC2992 makes it an ideal IC for several applications such as blade servers, advanced mezzanine cards, and 48 V telecom equipment.

Users with equipment using negative supply or supply greater than 100 VDC can make use of the onboard shunt regulator. The LTC2992 has registers that one can access with the I2C bus, and it uses these registers to store the measured values. It can measure current and voltage on-demand or continuously, using these to calculate the power, and stores this information along with maximum and minimum values in the registers.

The LTC2992 has four GPIO pins, which the user can configure as ADC inputs for measuring neighboring auxiliary voltages. Over its entire temperature range, the LTC2992 takes measurements with only ±0.3% of the Total Unadjusted Error (TUE). For any parameter going beyond the thresholds programmed by the user, the LTC2992 raises an alert flag in the specified register and on the specified pin. This is according to the alert response protocol of the SMBus.

The I2C bus on the LTC2992 operates at 400 kHz and features nine device addresses, a reset timer for a stuck bus, and a split SDA pin for simplifying the opto-isolation for the I2C. Another version of the IC, the LTC2992-1 offers users an inverted data output pin for the I2C. This makes it easy for the users to interface the IC where the opto-isolator has an inverting configuration.

The ICs, LTC2992 and LTC2992-1, are both available in automotive, industrial, and commercial versions. Their operating temperature ranges are -40°C to 125°C for automotive, -40°C to 85°C for industrial, and 0°C to 70°C for commercial applications. Linear Technology Corporation makes both versions of the IC in packages of 16-lead MSOP and 16-lead 4 x 3 mm DFN, and both versions are RoHS-compliant.

Most electronic applications require monitoring of current, voltage, and power at board level. Knowing the key system parameters provides valuable feedback, allowing users to monitor the health of their systems and make intelligent decisions. They help in determining whether a system is operating properly, efficiently, or even dangerously. Users can choose for various types of monitoring ICs, ranging from hot-swap dedicated power ICs to temperature monitors.

Advanced PCB Technologies — High Density Interconnect

Engineers often face a peculiar dilemma. On one hand, they need to enhance the functionalities of electronic gadgets they design so that customers have more value for their money, while they are constrained to use a sleek form factor. Not only does this impose a tremendous challenge to cram many components within a highly restricted space, but the challenge extends to maintaining the quality and integrity of the design as well.

Designers meet the challenge in different ways. They use subminiature passive SMD components, often as small as 0402 (0.4×0.2 mm), special fine pitch ICs in packages such as CSP, TQFP, and BGA, and advanced printed circuit technologies that offer thin flexible, multilayer boards, especially the high density interconnect (HDI) types.

Designers use several advanced technologies in producing HDI boards. For instance, rather than using glass fibers for producing the base substrate, HDI boards use Polyimide and similar materials, as these are flexible, more durable, and can withstand very high temperatures without degenerating.

Designers use special plated through vias to interconnect different layers in a multilayer HDI board. Rather than drill holes in the PCB layers using metal drills, fabricators of HDI PCBs use lasers to drill extremely small microvia holes in the layer, which they later electroplate with copper. Since these microvias can be as small as 15-30 µm, they take up very little space on the PCB, leaving a large area for routing the traces.

Designers use traces with width as small as 20 µm to route the circuits on HDI PCBs. In combination with microvias, these thin traces allow them to achieve extremely high routing densities impossible to achieve on regular boards. This is especially helpful when designing with fine pitch ICs and high pin count BGA IC packages that have a pitch as small as 0.5 mm.

BGAs are surface mounting packages with solder ball arrays on their bottom surface. Large BGAs may have as many as 560 solder balls. With pitch size as small as 0.5 mm, it is nearly impossible for designers to run traces from each pad under the BGA. However, engineers have solved this problem in a rather unique way.

In regular PCB design, using vias within pads is taboo, as this causes dry solders. The plated through via wicks away molten solder, leaving very little solder between the pad and the IC pin. However, designers regularly use via-in-pads in HDI PCBs, as this allows them to save a lot of space that they can use for routing. Molten solder does not travel down the microvia in HDI PCBs, as fabricators fill them up and plate them over. This has another advantage, as filled vias become better conductors of heat.

Another trick a designer often uses for gaining higher routing density in HDI PCBs is placing different types of vias such as blind and buried types. Vias connecting inner layers in a multilayer PCB are buried vias, while those originating on one of the outermost layers and connecting to one of more inner layers are blind vias. Unlike a through via that passes straight through the board, designers can stagger blind and buried vias in different layers to achieve higher routing density.

What is a Programmable Logic Controller?

Programmable Logic Controllers (PLCs) are miniature industrial computers. The hardware and software in a PLC are meant to perform control functions. Specifically, a PLC helps in the automation of industrial electromechanical processes. This includes controlling machinery on assembly lines in a factory, rides in an amusement park, or instruments in a food processing industrial establishment.

Most PLCs are designed to facilitate multiple arrangements of analog and digital inputs and outputs. They typically operate with extended temperature range, resistance to impact or vibration, and immunity to electrical noise and disturbances. The basic sections of a PLC usually consist of two sections—the first, the central processing unit (CPU), and the second, an Input/Output (I/0) interface system.

The CPU uses its processor and memory systems to control all system activity. Within the CPU is the micro-controller, memory chips, and other integrated circuits for controlling logic, monitoring, and communications. The CPU may operate in different modes—programmable or run. The programming mode allows the CPU to accept changes to the logic received from another computer. In the run mode, the CPU will execute the program to operate the process.

In the run mode, the CPU will accept input data from connected field devices such as switches, sensors, and more. After processing the data, it will execute or perform the control program stored in its memory system. As the PLC is a dedicated controller, the single program in its memory is processed and executed repeatedly. The scan time, the time taken for one cycle through the program, is typically of the order of one-thousandth of a second. The memory within the system stores the program, while at the same time holding the status of the I/O and provides a means to store values.

Typically, industrial users can fit a wide range of I/O modules to a PLC to accommodate various sensors and output devices. For instance, there are discrete input modules for detecting the presence of objects or events using photoelectric or proximity sensors, limit switches, and pushbuttons. Similarly, with discrete output modules it is possible to control loads such as motors, lights, solenoid valves, mainly to turn them On or Off.

The PLC can be fitted with analog input modules to accept signals generated by process instrumentation such as temperature, pressure, flow, and level transmitters. The modules interpret the signal from their sensors, and present a value within the range determined by the electrical specification of the device.

In the same way, the PLC can use analog outputs to command loads requiring a varying control signal, such as analog flow valves, variable frequency drives, or panel meters. PLCs can also use specialized modules such as serial or Ethernet communications, and high-speed I/O or motion control.

The greatest benefits of a PLC are its ability to change and replicate or repeat the operation of a process while simultaneously collecting and communicating critical information. In the industry, all aspects of a PLC—cost, power consumption, and communication capabilities—are subject to consideration when selecting the right one for the job. Industry automation owes a lot to the PLC or Programmable Logic Controller.