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.

Motor Run & Motor Start Capacitors

Electric motors exploit the interaction between two magnetic fields for rotating a shaft. The stator windings generate one of the fields, and the rotor windings provide the other. In some DC motors, permanent magnets replace one of the windings, while the commutator, whether brushed or brush-less, changes the direction of the current in the other winding to continuously alter the interaction between the two magnetic fields to allow the motor to rotate.

In three-phase AC motors, the interaction between the three incoming phases creates the rotating magnetic field in the stator windings, and this pulls the rotor along, making it rotate. The so-called single-phase AC motor is, in reality, a two-phase AC motor that is operated with a single-phase supply, with capacitors generating the second phase. These motors require two capacitors, one to start the motor, and the other, to keep it running.

A capacitor is a device to store charge. In the DC circuit, a capacitor will charge up and stay that way until allowed a path to discharge. In the AC circuit, where voltage and current change polarity regularly, the capacitor charges up to the peak voltage in one cycle, then discharges and again charges up to the negative peak in the next cycle, with the rate of charging and discharging dependent on the capacitor value and the impedance in the circuit.

Another important factor is the voltage on the capacitor does not follow the input voltage while it is charging and discharging—it lags behind. Even though the supply voltage may be at its peak, the voltage on the capacitor reaches the peak only after the capacitor charges. Likewise, as the supply voltage moves towards the negative peak, the capacitor voltage follows more slowly as the capacitor has to first discharge. This lag helps to create the second phase for the motor.

A motor starting from rest requires a high starting torque, but once it has started moving, requires a smaller running torque to keep it in rotation. That means a larger capacitor is necessary for starting the motor—providing it with a larger starting current. In fact, motors use a centrifugal relay to cut out the start capacitor from the circuit after the motor has reached a certain speed. The run capacitor, though, has to remain connected to the motor at all times.

As the run capacitor is engaged in the circuit continuously, they are oil cooled and in metal, cases to allow heat dissipation. As they face peak to peak voltages all the time, their voltage rating tends to be on the higher side—typically, 1.5 times the line voltage, although the capacitance value may be low, ranging between 5 µF and 45 µF. On most 240 V systems, run capacitors are likely to be rated 370-440 VAC, and in 480 V systems, 600 VAC capacitors are more common. Run capacitors are rated for 100% duty cycle.

Start capacitors, being of larger capacity, are physically larger as well. As the start current does not need to be very precise, start capacitors are available as 8.3 µF, 15 µF, 43 µF, 60 µF, and above. Common voltage ratings for start capacitors are 110, 125, 165, 220, 250, or 330 VAC.

Storing Data with Light

Currently, we have several methods of storing and transmitting data. The most common method followed is storing data on a magnetic hard disk in the form of bits. Here minute magnetic domains form a North and a South pole pair, with the direction of the magnetization of the poles defining whether the stored bit is a digital 1 or a 0. Writing the data means physically switching the magnetization of the relevant bit, one at a time.

Switching or changing the magnetization of each bit requires the application of an external magnetic field, which forces the alignment of the poles to change to either up or down for representing a digital 1 or a 0 respectively.

However, it is also possible to use light to flip the magnetization. Two things are required here, one, very short laser pulses of femtosecond wavelength, and the second, synthetic ferrimagnets that respond to these laser bursts. Using laser and ferrimagnetic material makes data storage far faster compared to what can be achieved by magnetization alone. Ferrimagnets are materials that work with spintronics with the application of a femtosecond laser pulse, and that makes the whole process extremely fast and energy-efficient.

As such, light offers the most energy-efficient method of sending and receiving information. However, storing light is not an easy task. That is the reason data centers all over the world prefer to use magnetic storage methods such as tapes and disks, even though these methods consume a lot of energy to operate. This hybrid technique of storing information using lasers and electric current, developed by researchers at TU Eindhoven at the Institute of Photonic Integration, was presented in the journal Nature Communications. The new method combines the advantages of the high speed of light and ease of magnetic storage. They are using ultra-short pulses of light to write the information directly on a magnetic medium, the result is highly energy efficient and the speed of operation matches the speed of light.

Scientists using the above method of data storage with lasers, have another trick up their sleeve. They combined this optical switching with race-track memory. Here, the data is stored inside a magnetic wire and transported using an electric current. Now, as soon as the bit is stored at one end of the wire using the laser burst, it can be efficiently transported along by the current, freeing up space and thereby allowing the laser to write the next bit.

This efficient on-the-fly operation with the help of lasers and current using magnetic race-tracks does not require any intermediate electronic step. In fact, the physical analogy the scientists offer for this method is of a person jumping back and forth between two high-speed trains moving alongside each other, instead of using a station to change over from one train to the other. The laser and current method, therefore, represents faster speed and higher efficiency.

Obviously, the wires are actually micro-wires. The scientists who designed the system plan to reduce the wires to nano-scale in the future to enable them to be integrated inside chips. They are also working on reading information using optical methods.

Contactless Magnetic Angle Sensing

Contactless magnetic angle position sensors are now giving optical encoders a run for their money. This was recently demonstrated by Monolithic Power Systems at Electronica 2018. They had on display a unique non-automotive-focused electric vehicle, mCar, with motion control and angular sensors. According to MPS, their mCar demos two main functions—motor control elements, and angular position sensors.

As Quitugua-Flores, the mechanical engineer and primary designer of the mCar at MPS explains, the steering of the car is a complete drive-by-wire concept, and there is no mechanical connection between the tires and the steering wheel. A magnetic angle sensor detects the angle of the steering wheel and converts the signal to control the tire angle necessary for the various steering modes. The magnetic angle sensor provides visible feedback via a blue LED mounted on the dashboard, with the LED lighting up when the driver turns the steering.

An electronic system takes in the magnetic angle sensor information and feeds it wirelessly to the rest of the car, thereby instructing the wheels to turn. The angular sensor, along with the board and antenna for sending the wireless signals is attached to the steering column.

The throttle and brake pedals use similar rotary magnetic angle sensors and send their signals wirelessly just as the sensor on the steering wheel does. Pivots on the brake and acceleration pedals house the angular sensors, and they measure the angle of depression of the pedals.

However, MPS has made the mCar as an R&D application, and they have not yet approached the National Highway Traffic Safety Administration (NHTSA) for compliance with their safety regulations.

According to Quitugua-Flores, another aspect of the mCar is its driver seat pivots freely. The front and rear suspension modules keep the seat suspended such that when the mCar enters a curve, the seat tilts into the turn just as it happens in a motorcycle or a plane. This keeps the driver firmly in the seat in a turn, rather than being literally pushed out of it.

An angle sensor attached to the seat detects the rotational position and sends the information to the suspension control. The shock absorbers in the mCar come with individual integrated BLDC motors that can change the length of the shock absorbers independently. Therefore, the suspension has complete control over camber or the vertical tilting of each wheel. As the frame of the mCar tilts when turning, the suspension changes such that each tire tilts in a corresponding direction—just as a four-wheeled motorcycle does.

Shafts suspending the driver cockpit also have angular sensors attached to them. This allows the driver to enjoy a smooth ride by controlling the behavior of the suspension.

According to MPS, the mCar is only a demonstration for the effective operation of a sensing and motion control for a demo Electric Vehicle but is not a high-precision application. For systems requiring high-precision applications, MPS has demonstrated a robotic arm that allows seven degrees of freedom.

With sixteen angular sensors inside it, the arm demonstrates the capabilities of the current generation of MPS angular sensors for precision applications.

Metamaterials Improve LIDAR

Light Detection and Ranging or LIDAR is a remote sensing method. The technique uses the time of flight of pulsed laser light to measure variable distances. Airborne systems record additional data, which, when combined with the data from the light pulses are able to generate three-dimensional information about the neighboring environment that offer precise surface characteristics.

In general, a LIDAR comprises a laser, a scanner, and a specialized receiver for Global Positioning System or GPS. Although so far, common platforms for LIDAR used helicopters and airplanes for acquiring data over broad areas, autonomous vehicles are now using Topographic LIDAR extensively for navigation through road traffic using a near-infrared laser to map the nearby area.

Using LIDAR systems help scientists and engineering professionals examine both artificial and natural environments with precision, accuracy, and flexibility. As the market for LIDAR is still in its nascent state and its technologies fragmented, there are only about 70 LIDAR companies worldwide, making it a hotbed of new technology.

For scanning a wide area, conventional LIDAR systems have to rely on electro-mechanical spinners to steer laser light beams. Not only does this method reduce the scan speed, but it also affects measurement accuracy. A Seattle-based, venture-backed startup, Lumotive, is now developing a new technology that will change the way LIDAR systems function.

According to Bill Colleran, co-founder, and CEO of Lumotive, they are developing a LIDAR system that can steer beams but has no moving parts. Rather, their patented technology uses the light-bending properties of metamaterials such as Liquid Crystal Metasurfaces or LCM to steer the laser beams. Bill calls the use of such metamaterials “pivotal technology.”

However, Lumotive is not the only player in the field to offer LIDAR systems that do not rely on mechanical scanning. Other rivals have used optical phased arrays or MEMS mirrors to claim their LIDARs use a lower number or no mechanical components.

According to Bill, Lumotive LIDAR systems use LCM semiconductor chips. The main advantages of LCM are it offers a large optical aperture of about 25 x 25 mm, resulting in a longer range for the LIDAR, along with a 120-degree field of view. The high performance of the LCM comes from its fast-random-access beam steering capability.

When a laser beam shines onto the Lumotive’s liquid crystal metasurface chip, programmed electrical signals can direct the reflected light into any direction within its 120-degree field of view.

Metamaterials are mostly artificially structured materials that allow unprecedented control over their properties, specifically in new ways for controlling the flow of electromagnetic radiation including light. For instance, Kymeta has a flat-panel satellite antenna technology based on metamaterials.

Kymeta’s antenna can move electronically. It does not require the conventional phase shifters, amplifiers, and related components on its surface. This not only cuts down the cost, it also consumes far less power and does not require cooling devices. Compared to conventional antenna systems, Kymeta is able to increase the density of their flat-panel antenna elements dramatically, while controlling the phase and amplitude simply by activating or deactivating individual antenna elements. Lumotive have adapted the Kymeta antenna’s metamaterial architecture to their LIDAR system.

Role of LEDs in Horticulture

While LEDs have revolutionized indoor and exterior lighting methods, they have been revolutionizing operations involving indoor grow facilities. This is mainly because LEDs are highly flexible in their spectral output, while their efficiency is very high. That means they emit much lower heat.

A new standard from ASABE specifies the performance of LED lighting products for horticulture applications. The standard spells out the test methods to measure the optical radiation from LEDs in the range 280-800 nm. Note the visible spectrum covers about 390-700 nm.

According to the Standards and Technical director of ASABE, Scott Cedarquist, in horticultural applications, LED lighting has generated very high levels of interest in their projects in the last 20 years. Therefore, horticultural lighting makes use of several terminologies that are primarily focused on plants. Two of them are PPFD or Photosynthetic Photon Flus Density and PPF or Photosynthetic Photon Flux.

While PPFD measures the number of active photons falling on a surface per unit area per unit of time, PPF is the number of photons created by a lighting system per second.

Horticultural lighting primarily focuses on delivering photons that initiate photosynthesis and other processes in plants. These spur plant development as they excite electrons. Horticultural applications use LED products that are different from those used for general illumination. The difference is primarily that the former has a wider spectral output typical for horticultural applications. This is necessary as different plants respond differently to various wavelengths.

According to academic and industry research, each type of plant has a specific light recipe that helps the plant to yield higher growth in the shortest period. The recipe holds the variation in optical spectra for optimizing the overall growth of the plant, thereby improving desirable plant characteristics. For instance, increasing the potency of cannabis or the flavor of vegetables.

The light output from LEDs has another characteristic. Not only do LEDs provide a precise output spectrum, but this spectrum can also be tuned to optimize the spectrum for different plants and the phases of their life.

LED lighting products are primarily used in horticulture as vertical farms. This is due to the far lower heat output from LEDs as compared to that from other light sources. This allows the LEDs to be interspersed very close to the plants without damaging them. Therefore, facility managers are able to maximize the use of available space. This has made vertical farming very popular in urban areas. Horticulturists are making use of abandoned buildings which they are converting to grow food, thereby making new products available at cheaper rates.

The high efficiency of LEDs also helps considerably in energy savings. However, grow facility managers are more interested in the yield of the crop, and use of LEDs for high-value crops such as cannabis offer revenue increase from higher yield and shorter life cycle, rather than from energy savings. Similarly, more traditional crops such as flowers and leafy vegetables also use LED lighting not for energy savings, but rather for the ability to produce more crops in a shorter period.

Automation Applications of Thermopile Arrays

For a temperature difference occurring between two ends of a thermocouple, it develops an electrical voltage difference. A series of such thermocouples form a thermopile sensor, with each element being a thin wire made from two materials differing in the thermal activity. All the hot junctions of the thermocouples are placed on a thin common absorbing area that forms the sensor face, while the cold junctions are placed on a heat sink with a high thermal mass.

As an instrument, the thermopile sensor can remotely measure the temperature of objects and people. The operation of the thermopile is better understood in terms of heat flow rather than temperature rise. Any object with a temperature higher than the ambient is actually sending out heat in specific spectral characteristics and density. According to primary thermodynamics, heat flows from an object at a higher temperature to another at a lower temperature, causing a change in energy levels of both the objects in the process.

The amount of heat absorbed depends on the field of view and surface area the Thermopile sensor presents to the heat source. Heat reaching the thermocouples inside flows through the membrane structure of the thermopile, finally reaching the heat sink or the housing bottom. This heat flow causes a difference of temperature on the ends of the thermocouples located on the absorber and those on the heat sink, ultimately resulting in a voltage difference between the ends of the thermopile sensor.

Compared to the traditional contact-based temperature sensors, thermopile temperature sensors are of the non-contact type, and hence, they are more popular industrially. Rather than use conduction for heat transfer, thermopile temperature sensors use infrared radiation, allowing better reliability and performance in several constrained applications.

The voltage difference on the ends of the thermopile sensor is analyzed by a Thermopile sensor IC, which provides temperature readout in a convenient digital format. Continuous improvements in this field are resulting in devices that consume reduced power, are smaller and more affordable. This translates into more application opportunities for thermopile temperature sensors in home appliances, office equipment, medical instruments, and consumer devices.

Thermopiles with single-element infrared sensors are popular in the low-end market, as they are good for detecting the presence of stationary warm bodies in a room. However, these simple sensors are unable to provide the direction of movement of a moving object in their field of view. For this additional functionality, engineers use thermopile arrays.

Rather than use a single sensing element as in a thermopile temperature sensor, thermopile arrays use multiple IR sensing elements working together. Integrated signal processing capabilities and coordinated sensing elements of the modern thermopile arrays allow the devices to measure not only absolute temperatures but also temperature gradients. This allows thermopile arrays to sense the direction of movement of the heat source, such as up, down, left, right, and diagonally. Thermopile arrays can detect the presence of multiple objects or people even as they move about in different directions. This allows them to sense the proximity of the heat source and handle control tasks with simple gestures.

Thermopile Sensors for IoT

mart and connected technologies are presently driving the astonishing growth of the Internet of Things (IoT). However, growth in these technologies is, in turn, a result of the tremendous development of various sensors. According to the Boston Consulting Group, by 2020, expect to spend US$ 265 billion for IoT technologies, services, and products. Much of this growth will owe its progress to that of sensors.

One can now find sensors almost everywhere, for instance, in smart retail, smart healthcare, and smart homes. Today, most people start their day with pressing a couple of apps while still in bed, thereby turning on the high-end coffee maker for the first-morning cup, or their night adjusting the climate control zoning system for keeping the bedroom in that ideal sleeping temperature.

As an example, a large health insurer in Australia is placing sensors throughout the house of elderly members for monitoring their health and preventing them from falling. They place sensors within refrigerators, medicine cabinets, bathrooms, and doorways. The sensors monitor movement by tracking the temperature within the home. Any break in routing such as a change in the temperature notifies the family immediately.

Viewers of professional golfing can see information on the heart rates of the players on their TV screens thanks to a special camera and sensors monitoring the faces of the players. This contactless vital sensing technique allows TV viewers to read the stress levels of the athletes as they play.

The past decade has seen a drastic drop in the prices of sensors as a result of the advancement of technology. This reduction has exponentially increased the use of sensors not only in civilian applications, but also in military, aerospace, and in collision avoidance systems in the automotive industry.

Advances in complex micro-electro-mechanical systems (MEMS) and thermopiles are improving uncooled IR sensor technology. This MEMS-based technology offers free-standing thermal isolation structures surrounding a printed thin-film IR absorber. This allows the collection of radiated power to determine the temperature of a remote object. Using semiconductor technology, it is now possible to add hundreds on thermocouples on several square millimeters of a thermopile sensor. Besides being small and reasonably priced, these thermopile array sensors are smart enough to be accurate with faster response time. It makes them ideal for building automation, people counting, security systems, medical instruments, and more.

For instance, the 8×8 thermopile array device is a sensor with 64-pixel IR sensors fitting within a surface mount package that can withstand reflow soldering. Apart from a silicon lens that collects the infrared energy, the package consists of a digital ASIC, a MEMS detector chip, and RF-shielded metal cover, and an I2C interface.

While operating, the thermopile array sensor has a 60-degree field of view for absorbing emitted thermal energy. The 64 sensing elements in the array individually convert the absorbed thermal energy to produce a proportional output signal. After amplification, an ADC converts these analog temperature signals to digital, while also referencing them against the ambient temperature value measured by a thermistor. A microprocessor collects the digital data and proceeds to map the temperature from individual thermopile elements into a thermal representation of the entire field of view.

Why you need Sensor as well as PLC Data

In the Industry, collection of IoT data, specifically that from manufacturing processes is very important. Apart from the quantity of the data collected, the quality of information from various machines is also equally vital for analysis, and to make decisions.

IIoT puts a lot of stress on the usefulness of predictive analytics based on big data. According to the Forbes magazine, big data offers the volume, speed, and variety of information about important effects that traditional methods of empirical research and the human eye is unable to capture. Therefore, big data becomes the primary step towards generating valuable insights from evidence-based interventions. From a theoretical and practical perspective, big data not only helps to predict outcomes, but it also helps in explaining them, especially in understanding the underlying causes.

Companies usually build plug-n-play adapters for controls, thereby enabling them to capture hundreds of data points directly from PLCs. Although this generates vast quantities of data for analysis, and a large part of it will be helpful as deep data, there will always be some part of the data that will remain useless, as will some results.

By taking the analysis down to a more granular level, deep data can eliminate irrelevant information and focus on the streams for a certain course of investigation. Analyzing deep data offers more accurate overall predictive trends.

Data from a specific sensor on a machine offers a snapshot within a designated timeframe. Sensor data monitors specific situations, such as vibrations that signify to an operator the state of operation of the machine—on versus off. However, all sensor data may or may not be useful during a review or analysis.

On the other hand, PLCs can collect large amounts of data, and when combined with sensor data, allows the operator to gather a full picture of the machine status at any time. This data can help to monitor inputs to and outputs from a machine, and based on programming, can make logical decisions when necessary.

Older machines with legacy controls and those with no controls need additional integration/hardware support for capturing data. While auxiliary hardware can capture digital and analog IO, adding sensors can generate additional data points.

The ability to capture deep PLC data and data from sensors that monitor specific items that the PLC cannot reach forms the basis of high-quality analytics and results—all the more reasons for the necessity of sensor as well as PLC data.

For instance, while a sensor may provide information on the vibration limits of a certain machine or parts thereof, the PLC data from the machine may include parameters signaling an impending fault. Therefore, the PLC data offers the ability to control the operation of or sequence of activity of a nearby a machine. When the sensor data signals one or more parameters are beyond the programmed limits, the operator can respond quickly, and need not wait for analysis.

Therefore, using both sets of data from sensors as well as from PLCs offers more information to the user than either on their own do. This allows the operator greater flexibility for avoiding expensive downtimes and maintenance issues.

What are Diode Array Detectors?

High Performance Liquid Chromatography or HPLC uses diode arrays for recording the absorption spectrum of samples when ultraviolet and visible light passes through them. This enables the user to gather qualitative information about the samples. Major applications of HPLC diode array detectors include agriculture, environment, and industries such as petrochemical, energy, chemistry, life sciences, and pharmaceuticals.

Diode array detectors of HPLC have the advantage of the ability to select the best wavelength for analysis. Therefore, when selecting a diode array for use as a detector in HPLC, one should consider features such as resolution, wavelength range, near infrared ranges, baseline stability, low noise, and peak integration. Some vendors also offer the technique of detecting using a configurable light path formed from fiber optics.

An HPLC has a tungsten lamp emitting light in the visible range. This light enters a deuterium lamp that adds the UV to the visible light, forming a polychromatic beam. As this beam passes through a flow-cell, the sample in the flow-cell absorbs certain wavelengths. The output light then enters a grating, which splits the polychromatic beam into its constituent wavelengths and these pass through a slit before falling on an array of photodiodes, which measure their intensities.

As the diode array detectors measure all wavelengths simultaneously, it is able to acquire the spectra as well as the multiple single wavelengths at the same time by the different diodes in the array. The diode array detector has high selectivity, as it can identify different substances by their spectra.

One of the major advantages of the diode array detector is the tungsten lamp offering light in the extended visible wavelength. Additionally, by controlling the temperature of the optical unit of the diode array detector, its signal quality improves dramatically. Moreover, the diode array detector does not require a reference diode.

While other types of detectors use a diode for reference, for a diode array detector, there is no direct measurement of a signal when there is no absorption. Rather, the HPLC uses a detector balance. This happens automatically as the user switches the instrument on or just before conducting a measurement. The user achieves a detector balance by setting the absorption values for all wavelengths to zero. According to the Lambert Beer’s law, this allows the measurement of all intensities during an experiment to be made relative to this zero absorption intensity.

To cater to baseline changes or drift during a measurement, the diode array detector uses a reference wavelength. The user has to select a specific wavelength as reference, and make sure there is no absorption in the wavelength during the entire chromatography measurement. The user then uses the relative changes of the reference intensities for correcting the proportional changes occurring in other wavelengths.

Five factors majorly affect the measurements done by HPLCs using diode array detectors. These are the slit width, the bandwidth, the response time, and the flow cells. The user has to adjust all of them to obtain the best response from the diode array detector when testing the absorption of a sample. For instance, the slit defines the amount of light the detector measures. The bandwidth defines the window for the data acquisition. The response time defines the time resolution, and the flow cell defines the flow range.