As Power over Ethernet (PoE) evolved, it’s grown to become a global market that’s projected to exceed $3 billion by 2025, more than triple of today and eight times that of 2015. Even these rosy estimates might be conservative as analysts have increased their projections every year. And, it is not hard to see why. The IEEE 802.3 PoE standard has finally achieved the ability to deliver about 90W over a single Category 5e (CAT 5e) cable. As more cities throughout the world become connected, PoE’s capability of delivering about 90W over a single CAT 5e cable could not have come at a better time.
When PoE first appeared in 2003 as the IEEE 802.3af standard, it could handle only 13W at 350mA over a distance of 100m. That was impressive at the time as it could power some Voice over Internet Protocol (VoIP) systems, CCTV cameras, Radio Frequency Identification (RFID) readers, and other low-power systems. However, 13W was not enough to serve applications such as video-conferencing, Wi-Fi routers, or pan-tilt-zoom or heated cameras. The IEEE bumped up the DC power level to 25.5W at 600mA —except in non-standard variants—with the 802.3at standard in 2009. This increase in the DC power level enabled manufacturers such as Analog Devices to advance their PoE architecture. Analog Devices’ proprietary Linear Technology Power over Ethernet (LTPoE)++ architecture (Figure 1) handles up to 90W, is backward-compatible back to 802.3af, and provides other features as well.
Figure 1: The LTPoE++ architecture provides 90W at the powered device with a simplified approach. (Source: Analog Devices)
However, on September 27, 2018, IEEE announced the finalization of the PoE standard 802.3bt that increases maximum power to about 90W. The IEEE 802.3bt PoE standard signified a big leap forward because:
Now, for the first time, the vast majority of devices within all types of buildings can avail themselves of combining data transfer with DC power delivery via Ethernet. In smart cities, LED luminaires with characteristics that can be adjusted and monitored are increasingly replacing light sources such as sodium vapor. Additionally, with Ethernet easily accessible in many locations, PoE can supplement or replace the wireless solutions for lighting control that are being installed today.
Along with benefits to end users, 802.3bt-based applications present a major opportunity for manufacturers of controllers, ICs, and many other Ethernet components required to support the higher power levels. Analog Devices’ LT4295 Powered Device (PD) Interface, for example, accommodates up to 71W with end-to-end efficiency greater than 94 percent. On the Power-Sourcing Equipment (PSE) side, the Texas Instruments (TI) TPS23880 (Figure 2) is a PSE controller for detecting powered devices with a 90W capability and includes programmable Standard Random Access Memory (SRAM), which allows it to be upgraded via Inter-Integrated Circuit (I2C).
Figure 2: The TPS23880 eight-channel PSE controller includes programmable SRAM for in-field firmware updates. (Source: Texas Instruments)
It will probably take years for the electronics manufacturers and end users to fully ingest 802.3bt, so further standard-based enhancements could be years away. Meanwhile, other alternative solutions are using PoE to serve small cells that often consume 150W of power as a stand-alone system. Other non-standard, proprietary approaches—that might or might not be usable within a standards-compliant environment—are also likely to appear that will further extend power handling.
(Source: Jakub Krechowicz/Shutterstock.com)
Power over Ethernet (PoE) evolved in response to the growing need for fast, cost-effective network communication among powered devices (PD). The Institute of Electrical and Electronics Engineers (IEEE) developed safety standards to support the devices sharing a network connection. The IEEE has ratified and supported several versions of the standards since 2003. For slower 10 Base-T at 10Mbps and 100 Base-TX at 100Mbps transport, only two of the four Category 5 (CAT5) twisted pairs are used for signaling, leaving the other two twisted pairs to be used for transporting power to the end device (Figure 1).
Figure 1: The Data Delivery Over Two Pairs diagram illustrates a two-pair power connection. Power is delivered on the red pair only, while all four pairs can deliver data. (Source: Microchip)
Variant standards use the typically unused wires (Variant B) for power and ground. At the same time, Variant A rides the signal over power such as the -48 volts used in phantom power for audio condenser microphones. This clever technique biases each twisted pair with a voltage differential. This allows power to be extracted without interfering with the signals, which are differential relative to each voltage potential.
4PPoE, another shifting standard, uses all four twisted pairs for power and permits higher levels of power for more than just electronics, including motorized cameras, emergency lighting sources, vent actuators, relays, and pumps (Figure 2).
Figure 2: The Data Delivery Over Four Pairs diagram illustrates a four-pair power connection with power delivered over all eight wires. (Source: Microchip)
It is interesting to note that PoE is not the first powered networking technology. Decades ago, RS-232-based networking schemes used 4-wire RJ-11 cabling to supply transmit/receive and rectified AC over long distances. The rectified AC looked like AC so as not to be limited by cable impedance, and all had a common ground reference for the NRZ (Non-Return-to-Zero) signaling.
With Wi-Fi®, Bluetooth®, Zigbee, ultra-wideband (UWB), and so many other wireless protocols available that have a proven track record of effectiveness, why would anyone want a wired connection? Foremost, not every remote location that needs to be controlled or monitored has access to power. Buried sensors and actuators in a building can be in crawl spaces, attics, inside vents, and even locations where people cannot fit. A self-contained powered and wired connection might be the only solution. Likewise, critical systems such as emergency lighting might lose main power but still can operate on the PoE power. This is especially critical during emergencies such as in skyscrapers where lighting is maintained in escape stairwells. A wired connection is much harder to defeat because wireless can more easily be jammed. This is an important consideration in any security system.
Early 2003 802.3af standards could source 15.4W, which is plenty of power for embedded, buried, and distributed sensor systems. Cameras, internet protocol (IP) phones, and access points for wireless LANs also took advantage of this. The 2009 IEE 802.at standard allowed up to 30W per cable run, opening the door for potentially more power-hungry applications such as user-interface terminals and low-level lighting. Loud sound and siren systems were now also feasible.
The latest IEEE 802.bt standard ratified in 2018 is gaining traction and ups the ante to 60W for the 802.3bt type 3-class devices and 90W for the 802.3bt type 4-class devices. This not only provides power for single-port endpoint applications but also allows remote multi-port implementations, each capable of supplying power that can accumulate up to the 90W of the multi-port switch. This can also allow solenoids, motors, and other electromechanical functions such as emergency door opening or locking cockpit systems.
Interfaces between PoE and USB-3C are becoming more popular with the latest PoE and USB standards. This could allow laptops, tablets, and more sophisticated user interfaces to connect to a wired network that provides power and data for use and recharging.
There is more to this than meets the eye. Bridges between wired PoE ports to USB-3C ports could change how data flow is architected, even in houses and apartments. Although Wi-Fi is easy, the more people and devices trying to compete for the same airspace can introduce lag times and performance degradation. Takeaway data hogs such as streaming TVs from the Wi-Fi space and usable performance can return to heavily congested traffic areas like apartment buildings. With wired USB-3C ports, handheld devices, fixed-function units such as whole-house A/V distribution user interface, cloud, and IoT devices have more access to charger ports.
Many buildings already have Ethernet wiring in place, along with switches and even routers. Using this internet and cloud connectivity, as well as the backbone for re-architecting data flow and preserving the use of legacy systems, is important for using standard functions and limiting choices for who uses proprietary enhancements to the standards. If a piece of equipment adheres to the present standards, and as long as new equipment preserves backward compatibility with legacy systems, then your network can optimize data flow and performance.
Microchip’s multi-Power over Ethernet (mPoE) technology seamlessly and efficiently powers wired network devices, making it the ideal solution for Ethernet-based applications. Leveraging a uniquely designed algorithm, mPoE enables backward compatibility with pre-standard devices while supporting all IEEE® PoE standards. Microchip mPoE is an excellent solution for traditional network devices such as IP phones, Wireless Access Points (WAPs), IP surveillance cameras, 5G small cells, LoRa® gateways, LED luminaires, access control terminals, and other IoT devices.
Designing flexible, scalable, and reliable future-proof networks capable of accommodating business growth is essential. As the industry adopts the latest generation of PoE technology for managing data and power over a single Ethernet cable, companies face the challenge of making pre-standard PDs work alongside new IEEE 802.3bt-compliant PDs in a single Ethernet infrastructure. Microchip’s Power Source Equipment (PSE) chipsets with mPoE enable both pre-standard and IEEE-compliant devices to work together on the same network. The PoE injectors/midspans and PoE switches implement this unique technology to allow quick and simple deployment of Microchip mPoE in any network without changing existing switches or cabling. Microchip mPoE solves interoperability issues between different PoE standards and legacy solutions to provide an international network power standard.
Microchip mPoE supports PoE 1, PoE 2, PoE+, IEEE 802.3af/at/bt, legacy af/at, 12.5K, UPoE, Class 4 60W, and PoH standards concurrently. This innovative technology enables flexible and quick network design upgrades to address business requirements. Microchip mPoE offers the scalability and interoperability necessary to power IoT networks not only today but well into the future.
Microchip provides several configurations of single-port plug-and-play PoE 802.3bt modules for original equipment manufacturers (OEM) into mid-span 60W applications in Japanese, European, and American standards. Supporting 10/100 and 1G speeds, the single RJ45 connector delivers 60W. With legacy support and models such as the outdoor-ready PD-9501GCO IP67 Single-Port PoE Midspan primed to use off-the-shelf, infrastructure can be easily built into new and existing structures supporting these enhanced capabilities and advantages. Multi-port off-the-shelf solutions are also ready to embrace. Units such as the PDS-408G PoE Switches are 8-port PoE BT switches with up to 1G speeds and delivering up to 480W.
Designers can use the Microchip controllers to design their integrated Ethernet, USB, mixed-signal devices, and even leverage experience with past Ethernet designs to incorporate PoE advantage of PoE Power switch devices such as the PD69208 Ethernet ICs (Figure 3). Development kits such as the PD70xx & PD-Imxx PoE Development Tools can ease designers new to this technology into a rapid, low-cost, low-risk way of testing, evaluating, and developing with this technology.
Figure 3: Adding Power over Ethernet to conform to 802.3bt specifications is simplified using power switch parts and isolation. (Source: Microchip)
Wired Ethernet provides secure, reliable connections for an increasing number of PDs. Since adopting the first PoE standard in 2003, PoE use dramatically increased and made headway into new applications. The main limiting factor affecting PoE use in new applications is the amount of available power. Although 15.4W at the power source is sufficient for most IP phones and 802.11a/b/g access points, it does not meet the demand for an even higher power to support additional devices, such as PTZ security cameras, kiosks, POS terminals, thin client, 802.11ac and 802.11ax access points, small cells, and connected LED lighting, The latest itineration of the standard, IEEE 802.3bt, enables delivery of 90W over four pairs of CAT5e cables and above.
Microchip’s mPoE technology powers any wired network device seamlessly and efficiently leveraging a uniquely designed algorithm. This technology enables backward compatibility with pre-standard devices while supporting all IEEE PoE standards. mPoE supports PoE 1, PoE 2, PoE+, IEEE 802.3af/at/bt, legacy af/at, 12.5K, UPoE, Class 4 60W and PoH standards concurrently. This versatile technology enables flexible and quick network design upgrades to address ever-evolving business requirements.
Power over Ethernet (PoE) is a technology whereby standard Ethernet wiring does double duty, both as a data transport facility and a means to supply power to remote devices. This provides many advantages in installation simplicity and interconnect efficiency. PoE has found wide use in applications like security cameras, IP telephones, wireless access points, and light fixtures for smart buildings. However, there are shortcomings to standard PoE, and this blog suggests some techniques to help improve it.
The original PoE standard is IEEE 802.3af, which specified 15.4W of 48V launched into standard CAT-5 twisted-pair Ethernet cables. Later variants include 802.3at., which can launch 30W, and 802.3bt, which can launch 60W or 100W. There are also a number of non-standard implementations that can achieve higher powers or longer reach.
PoE systems work based upon the flow of energy supplied from a power sourcing equipment (PSE) endpoint, through the CAT-5 cable, and into a powered device (PD). This energy flow doesn’t hamper the delivery of bidirectional Ethernet data over exactly the same conductors. Because Category 5 twisted pair Ethernet cables are optimized for high-speed digital signals and not power delivery, there can be significant I2R losses in the cable. The standards allow for approximately 15 percent of the power launched at the PSE to be lost in the cable before it reaches the PD. DC-DC power converters at the PSE and PD convert between the approximately 48VDC on the PoE line and the internal voltages used in the devices at each end.
Notice the energy flow in standard PoE is unidirectional, always from PSE to PD. This limits the applicability of PoE, and also may require redundant PoE links in each direction if the PSE and PD ever need to exchange roles. There are several reasons why we may want bidirectional flows on those wires. One scenario involves a distributed energy system. Remote endpoints may have internal batteries, or could be associated with their own energy sources. A prime example could be a streetlight with an integrated photovoltaic array and battery. During extended dark stretches, the network supplies power over the PoE to keep the lights on and the fixture battery charged. However, when the sun is shining, and the internal battery is fully charged, the watts from the photovoltaic( PV )array on each streetlight could back-drive the PoE and help power the routers, stoplights and other loads deeper in the smart highway network, or sell surplus energy back to the grid. Another reason for bidirectional PoE is fault tolerance. In mission-critical IoT networks, routers and edge computers are often run in duplex pairs. A predominant failure mode of those devices is their local energy source or line-operated power supply. If a bidirectional PoE port interconnects two redundant routers, if the AC grid connection or power-supply module running either router fails, the bidirectional PoE can borrow some energy from its mate, transmit it in the appropriate direction over the PoE, and operate the failed node until it can be repaired. A third possible use case for bidirectional PoE could daisy-chain a linear array of IoT nodes, where power is fed into both ends, each of the two Ethernet ports on each device on a chain could either source or sink power. Finally, there are potential uses similar to USB-C ports on modern laptops, where sometimes the port drives a load and other times accepts a charger cable. Many potential IoT applications could use these bidirectional capabilities.
So, how does a single endpoint function both as a PSE and PD? The trick is to make the power converters at each end two quadrant. In traditional PoE, the power converter can only take in a specific voltage (say 380VDC right from the Power Factor Correction circuits on the AC input), and bulk convert it to the 48V (often set a bit higher, like 54V) used to drive the PoE power inserter transformers that in turn drive the cables. At the PD, again there is typically another DC-DC converter that takes the 48V from the PoE cable and creates the intermediate bus voltage (often 12V or 3.3V) used by the PD’s circuits. There is no way these one-quadrant supplies could ever reverse their energy flow. In bidirectional PoE, the power converters on both ends are converted to two quadrant operation, so when commanded, the internal switching regulator circuits can accept energy from either port, perform the appropriate voltage conversions, and deliver the energy to the opposite port. In today’s multi-output PoE devices like switches and routers, there is often one large bulk converter for all PoE ports. To convert it to bidirectional operation, there would have to be an individual dedicated two-quadrant power converter for each PoE line served because a subset of the active lines will be operating as PSEs, and the remainder as PDs.
Controlling the operation of these power converters could be tricky. The system would have to monitor the voltages and current flows on both ports of all power converters, and instruct the converters on each end of each line how to program its conversion direction, switching frequency, waveform, etc. In devices with capacity limits—like the main power supplies on central PoE routers, potentially with hundreds of ports—the control algorithms must be sure that the total energy in and out of all ports remains within those limits. The control system also has to exercise great care and precise synchronization as a PoE line switches direction, to avoid transients that, for example, could happen if both ends of a cable were programmed as high-power PSEs simultaneously.
US patent 9,531,551 includes details of how bidirectional PoE could work, the design of the two-quadrant power converters it requires, and the sophisticated control system it depends upon. Using this scheme, many advanced power distribution architectures are possible, which should enhance the versatility, efficiency, and reliability of PoE-based networks.
(Source: Anucha Cheechang/Shutterstock.com)
The power delivery capability of Power over Ethernet (PoE) is increasing, and with the latest IEEE 802.3bt standard, it can deliver up to 90W per channel. In this blog, we will examine the basic concepts behind the 802.3bt power sourcing and power delivery standards and how they have evolved to deliver the power requirements of today’s developments. We will also discuss why PoE is ideal for the built environment, bringing data and power to smart office lighting, room access, and heating controls.
The concept of delivering power over network cabling dates back to 2003 when the IEEE ratified the first Power over Ethernet (PoE) standard, an amendment to the core IEEE 802.3bt standard. The first standard, titled Data Terminal Equipment (DTE) Power via Media Dependent Interface (MDI), was IEEE 802.3af. The premise of delivering power in this way was based around cost-reduction initiatives when deploying the growing number of Ethernet-connected devices. Any networked device, whether a security camera, wireless access points, or an industrial sensor, requires power to operate. Typically, this would involve placing a line power socket in the vicinity of the device for its associated plugin power adapter, even though the low-voltage power requirement is relatively small, often no more than 10W. In most cases, the device might be the only reason a line power socket is required, and clearly, a wide-spread deployment might be associated with a significant electrical installation cost in advance of connecting everything up. Another benefit of PoE is to provide backup power to essential infrastructure, such as IP phones and security cameras, in the event of a line power failure.
Before delving more into PoE, let’s explain some of the terminology involved. Power over Ethernet is a means of delivering power from power sourcing equipment (PSE) via a link—the Ethernet cable—to a powered device (PD). The standard defines different types of devices based on the power delivery requirement. Type 1, for example, refers to the initial IEEE 802.3af standard that is specified to deliver up to 15.4W fewer cable losses to the PD load (Table 1). The IEEE 802.3at standard subsequently increased that to 30W in 2009, also known as PoE+, and introduced the Type 2 device. The voltage used for each pairset is in the range of 44VDC to 52VAC and is type-dependent.
Table 1: Power over Ethernet capabilities by type, class, and standard. (Source: Ethernet Alliance)
The power is delivered, along with the data, through two or more pairs of Ethernet cables (See Table 2). There are two kinds of PSEs defined:
In addition to type, a class parameter defines the eight classes, from 1 to 8, where 8 is the highest power, denoting the maximum power sourced or capable of being supplied across any PoE-based system.
The power interface (PI) is perhaps the most crucial aspect of any PoE interface (Figure 1). Two of the eight conductor cable pairs are always powered together, with two pairs—a positive and a negative pair—forming a pairset. The initial standard termed each pairset either Alternative A/Mode A or Alternative B/Mode B.
Figure 1: The architecture of the power interface of an eight-wire Ethernet cable. (Source: Ethernet Alliance)
As PoE becomes a viable way of powering wired networked devices, so did the limitation on the amount of power that could be delivered in this way. Type 1 and Type 2, while providing enough power for many simple devices, could not adequately supply sufficient power for PD applications such as point-of-sale terminals, intelligent IP-based PTZ cameras, and IP videophones. Also, the emergence of smart factory and smart office products are going to take advantage of the combined power and data capabilities that PoE yields.
In 2013, the IEEE 802.3 Working Group responded to the industry’s need for an increased power capability with the goal to deliver power over all four pairsets. This work culminated in the ratification and launch of the 802.3bt standard in September 2018, which introduced Type 3 and Type 4 devices and four power classes from Class 5 (45W from PSE) up to Class 8 (90W from PSE). The four pairsets are always used for Class 5 to Class 8 802.3bt compliant devices. The 802.3bt standard is also backward compatible for Type 3 PDs for two pairsets.
In the four pairset configurations, the 802.3bt standard also introduces two ways of powering one or more circuits within the same PD. Termed a single-signature or a dual-signature PD, the way the four pairsets are rectified and supplied to the load is illustrated in Figure 2.
Figure 2: Single-signature and dual-signature PD architecture. (Source: Microchip Technology)
If you are in the process of incorporating PoE capability into your next design, Microchip Technology offers a comprehensive portfolio of PSE and PD devices. Example products include the Microchip Microsemi PD69208, a PSE Ethernet IC series that integrates 802.3at, or 803.bt power delivery and analog data in a single QFN package (Figure 3). Supporting Ethernet supply voltage from 32V to 57V, they are suitable for use in both Ethernet switches and midspan devices. For power delivery applications, the PD70224EVB development board aids in the evaluation and prototyping of PD-based designs.
In addition to providing ICs, Microchip/Microsemi also provides a series of integrated midspan power injectors such as the PD-96xxGC series. Available in 1-, 6-, 12- and 24-port versions capable of delivering 90W to the IEEE 802.3bt standard, the midspans can power a wide variety of IP PTZ cameras, IP videophones, and thin client workstations.
Figure 3: Microchip Technology’s PSE and PD devices deliver up to 90W per channel and are ideal for PoE 802.3bt applications. (Source: Microchip Technology)
As the power delivery capability of Power over Ethernet grows, the scope widens to support more and more applications. Many of the new applications take PoE outside the traditional networked device arena to encompass the control and management of the built environment, such as occupancy-aware office lighting, heating and ventilation, and access security.
When designing a power delivery network (PDN), the decision to use power modules vs discrete power solutions requires careful consideration of design variables. Understanding the advantages of using power modules, particularly high-density modules offered by Vicor, over home-grown discrete solutions is important. By examining factors such as reliability, scalability, size, weight, and power design expertise requirements, we will delineate the differences between design options and distill the benefits of a modular approach to power system design.
Power modules have fewer points of failure because there are fewer design components. Compared to discrete designs, power modules require fewer connections, reducing the likelihood of quality defects during assembly. Moreover, with fewer assembly stages, there is a decreased need for board handling by operators, mitigating the risk of electrostatic discharge (ESD) damage during the manufacturing process. These factors contribute to improved reliability, making power modules a more dependable choice for power system design.
Vicor power modules are small and power dense (Figure 1). Given most power designs must fit into a very confined space, small power modules add flexibility. The compact design offers the ability to scale and accommodate changes in power requirements without costly and time-consuming redesigns. By reusing prequalified modules, designers can avoid additional testing, recertification and sourcing efforts associated with a complete redesign. This flexibility and scalability of power modules enables design changes to be implemented quickly and efficiently, resulting in shorter development cycles and cost savings. Ultimately, this translates into faster time-to-market.
Figure 1: Vicor power modules are small and power dense with an extended variety of available input and output voltages; hundreds of components tightly arranged within a miniature footprint; and isolation, regulation, conversion, and transformation in different combinations. (Source: Vicor)
When evaluating the choice between power modules and discrete designs, it is crucial to consider the entire life cycle of the product. In the case of a discrete design the burden of design, testing and validation falls solely on the in-house power design team. Furthermore, obtaining the necessary certifications from third-party agencies and managing the complex manufacturing and sourcing processes introduces significant risks and potential delays. Any scaling requirements can necessitate a complete redesign, further prolonging the development timeline.
In contrast, using power modules simplifies supply chain logistics and reduces the stress on the organization. These prequalified modules, such as the ones from Vicor, have undergone thorough testing and quality control, ensuring their reliability and compliance. Additionally, as power requirements increase, reusing the same modules allows for seamless scalability, eliminating the need for extensive redesign efforts.
Power modules offer a simpler approach to power system design that requires less expertise. With their miniaturized form factor and high power density, they occupy less physical space, leaving more room for other components on the PCB (Figure 2). The high efficiency of these modules also simplifies thermal management, reducing the complexity of cooling solutions. This simplicity translates into faster and easier design iterations, updates and overall system maintenance.
Figure 2: A simple, modular approach is flexible, easily scalable and requires less technical expertise to optimize a power delivery network. (Source: Vicor)
On the other hand, discrete power solutions present a complex landscape that demands extensive expertise, time and effort throughout the design process. These solutions involve the procurement, validation, and integration of many components (Figure 3). Even minor design modifications require a high-touch approach and can disrupt the project schedule and introduce unwanted risk.
Figure 3: Discrete solutions have more components to manage which increases design complexity. (Source: Vicor)
Discrete designs also suffer from inflexibility when it comes to adding more loads or adjusting power and voltage levels (Figure 4). Routing additional voltages consumes valuable space and adds weight to the system due to the requirements of larger boxes and cables. Moreover, these discrete solutions are susceptible to noise and external interference, impacting their overall performance and reliability.
Figure 4: The silver box is a nice plug-and-play solution, but often is large, heavy, and inflexible. (Source: Vicor)
In conclusion, when evaluating power system design options, power modules offer several significant advantages over discrete power solutions. Vicor power modules, with their advanced topologies, miniaturization, and thermally adept packaging, provide superior power density, efficiency and reliability compared to alternative discrete designs or silver-box options.
The use of power modules simplifies the design process, reduces the component count and likelihood of technical design errors, and enables faster time-to-market for new products. Additionally, the modular approach allows for easy scalability and flexibility, eliminating the need for time-consuming redesigns when power requirements change.
With the assurance of prequalified modules, simplified supply chain logistics and the ability to easily reuse modules and quickly scale PDNs, power system designers can focus on innovation and optimization rather than grappling with the complexities of a home-grown discrete solution. By choosing Vicor high-density power modules engineers can achieve efficient, reliable and scalable power delivery networks while saving valuable time and resources to get to market faster.
(Source: XP Power)
In precision analytical applications like mass spectrometry, devices require accurately specified and designed high-voltage power supplies.
Depending on the application, there are different demands on spectroscopy power supplies—a solution-based approach is needed.
Deploying multiple power supplies in the same equipment presents extra challenges. Here, we outline how to solve the most common design problems for high-voltage power supplies in mass spectrometry.
In mass spectrometry applications, high-voltage power supplies are required to deliver high voltage with minimum ripple and noise. In a high-voltage DC-DC converter, the ripple frequency is related to the switching frequency of the supply. Manufacturers such as XP Power offer a wide range of miniature high-voltage DC-DC converters with low ripple and noise.
To further reduce output ripple that’s related to switching frequency, designers can use additional filtering components, such as an RC low-pass filter. This consists of a resistor and a capacitor connected in parallel mode. The RC low pass filter sets a cut-off frequency, allowing signals with a lower frequency to pass through while reducing higher frequency signals.
Figure 1: A low-pass RC filter. (Source: XP Power)
First, designers determine which frequencies must be filtered out. In the following example, we selected 120kHz, the switching frequency of high voltage module C80N from XP Power in this circuit setup.
The cut-off frequency should be sufficiently different from the frequency to be filtered to allow for enough damping of the oscillation.
Figure 2: Calculation for a low pass RC filter (Source: XP Power)
For this example, we selected a 150kOhm resistor and a 2nF capacitor. The following oscilloscope diagrams show how the ripple and noise levels are reduced significantly.
Figure 3: Measurement: without low-pass RC filter. (Source: XP Power)
Figure 4: Measurement: with low-pass RC filter. (Source: XP Power)
High-voltage power supplies in mass spectrometry may operate at a different potential from the earth. That means that one power supply "floats" on another’s reference potential.
A detector floating on drift tube potential is an example of this arrangement. The best solution is to use an isolated high-voltage power supply, where the isolation rating of the supplies on higher potential must be at least equal to the floating voltage.
This galvanic isolation is achieved by the transformer and other devices if it is a regulated power supply. The following diagrams show how we can arrange cascading high-voltage modules.
Figure 5: Floating positive high voltage. (Source: XP Power)
Figure 6: Floating negative high voltage. (Source: XP Power)
In electrical ion lenses, there is often a need for bipolar high-voltage power supplies. In these electro-optic applications, there can be a requirement to swing from negative to positive high voltage, passing cleanly through zero. The diagram below shows a simple and way to achieve this.
Figure 7: Bipolar high voltage configuration. (Source: XP Power)
The output voltage of the first module is set to -1kV. The output of a second module can be referenced to this -1kV. The isolated 2kV module is set up in cascade over the module and is controlled from 0 to 2kV.
This module will generate a voltage that can be controlled linearly from—1kV to +1kV with no significant non-linearities nor instabilities in the transition from negative to positive.
It’s important not to leave the output section floating with the power on because the output may electrostatically charge to a voltage more than the isolation rating—this may cause damage.
This approach avoids the expense and space of a typical off-the-shelf bipolar power supply, providing a solution for OEM designs.
The diagrams below show how the high voltage is passed in a linear fashion through 0, and each value can be precisely adjusted, even near to zero.
Figure 8: Measurement: +1kV to -1kV linearly through 0. (Source: XP Power)
Figure 9: Measurement: output voltages in the range +1kV to -1kV. (Source: XP Power)
In mass spectrometers, many different electrical potentials may be juxtaposed, so interactions can occur between high-voltage power supplies.
XP Power recommends that systems with multiple high-voltage power supplies include supplemental protection circuitry for each supply to protect against fault conditions.
If an arc occurs between two high-voltage power supplies with different output voltages but the same polarity, the supply with the lower nominal voltage can be damaged by over-voltage.
The high-voltage arc can be a multiple of the nominal voltage of the module with the lower nominal voltage, which can lead to power supply failure. A good solution can be to add a high-voltage protection diode at the output of the high-voltage power source with the lower nominal voltage.
The diagram below shows how the power supply with the lower output voltage can be protected by a high-voltage diode.
Figure 10: Protection against voltage transients. (Source: XP Power)
The diode should have a reverse breakdown voltage, which is the highest voltage that can arc over to the module. The rated current should be higher than the highest current in the system.
When there is an arc between high-voltage modules with different polarities, each supply tries to deliver its rated current. This exposes the output to a supply with a higher current of opposite polarity.
The supply with lesser current may be forced to source or sink current beyond its capability, which can lead to overload and damage to the supply.
To avoid the problem, designers can use a reverse-biased diode at the high-voltage power supply output to return. The diode must be able to carry the current of the high-voltage supply that has the opposite polarity.
Figure 11: Protection against different polarity. (Source: XP Power)
Figure 12: Protection against different polarity. (Source: XP Power)
Accuracy, reliability, and additional specific functionalities are the key requirements for high voltage in mass spectrometry. Readily available, high-voltage DC-DC converters can meet those goals.
Maik Donix authored the Design Considerations for High-Voltage Power Supplies in Mass Spectrometry blog, which is republished here with permission.
Maik Donix has spent over 13 years working in the High Voltage industry having initially studied High Voltage Engineering at the Technical University of Dresden. His role at XP Power is an Application Engineer for High Voltage and Radio Frequency products.
In today's world of ubiquitous mobile devices, a low-battery notification can often feel like the digital equivalent of running out of gas on a deserted highway. Thankfully, portable power banks have come to the rescue, ensuring our devices stay powered when we need them the most.
Full disclosure: I wasn't immediately sold on portable power banks. In their early days, they seemed limited, catering to specific devices, limited in port offerings, or lacking the capacity to charge multiple gadgets simultaneously. Furthermore, their charging speeds were often underwhelming, with the units requiring several hours for a full recharge. Plus, the challenge of compatibility with varying power delivery standards was daunting. However, with advancements in technology, today's portable power banks have addressed these concerns, transforming them into indispensable tech marvels.
But what exactly has contributed to the impressive rise and excellent performance of these compact energy reservoirs? I believe it’s the result of a perfect storm: the fusion of advanced battery technologies, groundbreaking Gallium Nitride (GaN) chargers, efficient power delivery (PD) designs, and the widespread acceptance of USB-C™, all supported by economies of scale.
Take, for example, the Anker 737 PowerCore 24K Series 7 power bank, which I recently purchased (Figure 1). This 630g portable power bank is Power Delivery (PD3.1) and Quick Charge compliant and features six 4,000 milliampere-hours (mAh) lithium-ion (Li-Ion) cells for a 24,000mAh power bank capacity, equivalent to 86.4 watt-hours (Wh), which puts it nicely below the 100-watt FAA allowable limit for air travel.
Formula for converting a battery’s capacity from mAh to Wh: (mAh) x (V)/1000 = (Wh). For example, if you have a 4,000mAh battery rated at 21.6V,
the power is 4,000mAh x 21.6V / 1000 = 86.4Wh.
Thanks to GaN, the Anker 737 power bank features 140W high-speed output discharge capabilities. This power bank is designed for optimal convenience and speedy performance in a sleek, compact design. It boasts real-time temperature monitoring and universal device compatibility to ensure your mobile gadgets stay powered without a hitch. With robust charging capacities through two USB-C ports (140W maximum output each) and one USB-A port (18W maximum output), it can simultaneously energize three devices or enable pass-through charging for two devices while replenishing its own battery. Simply plug your cell phone, laptop, camera, or other gadgets into the power bank and connect it to the power source. This power bank outshines even the latest cell phones in recharge speed, boasting a formidable 140W recharging capability that soars from 0% to 100% in under an hour, storing more than 4X the charging potential of the latest flagship cell phones.
Figure 1: The Anker’s 737 140W output can charge power-hungry devices like a MacBook Pro 16-inch as effortlessly as charging a smartphone or earbuds. (Source: Author)
At the heart of every power bank lies its battery technology. Li-Ion batteries have become the industry standard due to their high energy density, long cycle life, and decreasing costs. They pack a lot of power in a small space, making them ideal for portable applications. As technology and manufacturing processes have improved, the cost of producing these batteries has reduced significantly, making high-capacity power banks more affordable for the masses.
Gallium Nitride (GaN) chargers have transformed the way we think about charging speeds. GaN is a next-generation semiconductor material that offers greater efficiency and can handle higher voltages than traditional silicon chargers. This translates to faster charging times and compact charger designs, ensuring your power bank recharges rapidly and is ready to go when you are.
Fast Power Delivery (PD) is a game changer, allowing devices to charge at optimized speeds safely. Combined with the pervasiveness of the USB-C port—now found on most modern smartphones, tablets, and laptops—users can enjoy a standardized, high-speed charging experience across multiple devices. This simplifies the charging ecosystem, ensuring that one power bank can serve a variety of electronic needs.
As demand for power banks has surged, large-scale manufacturing processes have evolved to meet the demand, resulting in economies of scale. This has made it feasible for companies to produce high-quality power banks at truly competitive prices, making them accessible to a larger segment of the population.
With great power comes great responsibility. The increased energy densities of Li-Ion batteries come with risks, such as thermal runaway—a chain reaction within the battery that can lead to overheating and potential explosions. The Battery Management System (BMS) is an unsung hero in this narrative. It monitors and controls the charge and discharge of the battery, ensuring it operates within safe parameters. The BMS also manages the battery's temperature, protecting it from potential hazards and ensuring longevity.
Given the inherent risks of Li-Ion batteries, organizations like the FAA have taken note. To ensure the safety of air travel, the FAA has imposed limits on the transport of spare (uninstalled) Li-Ion and lithium metal batteries, including power banks. Li-Ion rechargeable batteries are limited to a rating of 100 Wh per battery. These limits allow for nearly all types of Li-Ion batteries to be used by the average person in their electronic devices.
This week’s New Tech Tuesday features two key devices that help keep Li-Ion power banks safe for air travel.
The Texas Instruments BQ25756 is a versatile bidirectional buck-boost battery charge controller tailored for Li-Ion, Li-polymer, and LiFePO4 chemistries, spanning a vast 4.2V-70V input voltage and up to 70V battery voltage. Its standout features include 1-14 cell Li-Ion and 1-16 cell LiFePO4 support, a synchronous buck-boost controller with adjustable frequencies from 200kHz to 600kHz, and an integrated loop compensation with soft start. With bidirectional power support, the device efficiently manages charging, ensuring ±0.5% charge voltage accuracy and ±3% precision for both charge and input current regulations. Furthermore, its reverse mode aligns with the USB-PD EPR power profile, offering adjustable voltage (3.3V-65V) and current (400mA-20A) regulations. Designers will appreciate the ease of I²C control with resistor-programmable options, bolstered by a 16-bit ADC for comprehensive monitoring. Ensuring device and battery safety, it integrates overvoltage, overcurrent, battery short, and thermal shutdown protections. Informative status indicators provide real-time feedback, all packaged compactly in a 36-pin 5mm x 6mm QFN.
Next, Vishay / BC Components' AEC-Q200-Qualified NTC SMD Chip Thermistors are designed for precision, offering a wide temperature range of -55°C to +150°C. As negative temperature coefficient (NTC) thermistors, they excel in temperature compensation, sensing, and protection across diverse sectors, from automotive to consumer electronics. The NTCS series stands out for its robust construction and reliability in thermal cycling environments, suitable for both PCBs and flexible circuits. These thermistors utilize bulk ceramic technology and are available in standard surface-mount sizes: 0402, 0603, and 0805. They boast a high sensitivity, resistance values at 25°C from 1KΩ to 680KΩ, and beta values ranging from 3370K to 4125K. Moreover, they are RoHS compliant, cULus recognized, and can seamlessly integrate into high-volume, automated manufacturing processes. Key applications include battery management, automotive systems, consumer electronics, and medical devices.
In an era dominated by mobile devices, portable power banks have emerged as essential tools to prevent our gadgets from running out of power. Despite initial limitations, advancements in battery technology, the integration of Gallium Nitride chargers, and the adoption of universal USB-C have significantly improved their functionality and efficiency. Furthermore, economies of scale have made these tech wonders affordable for many. Technologies like the Texas Instruments BQ25756 and Vishay / BC Components' NTC SMD Chip Thermistors further enhance battery safety and efficiency. Ultimately, today's power banks are a testament to technological progress, ensuring our devices are always powered and ready to match the pace of our fast-moving world.
“Portable Power Bank Market Report Overview.” Business Research Insights, October 16, 2023. https://www.businessresearchinsights.com/market-reports/portable-power-bank-market-103127.
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