Posts

Current Sense Transformers Sense Current up to 40 Amps

Courtesy of Coilcraft

For Editorial Use:
English Word Document
Image
Coilcraft Press Room

Cary, IL, USA — Coilcraft’s new CST2020 Series current sense transformers sense current up to 40 Amps over a frequency range of 400 Hz to 1 MHz and offer 4000 Vrms isolation voltage between the sense and output windings. They provide Reinforced Insulation per UL 60950-1.

Coilcraft CST2020CST2020 Series current sense transformers provide output feedback for load current measurement and control in switching power supplies and overload/short-circuit protection. They are qualified to AEC-Q200 Grade 1 (-40°C to +125°C) standards, making them ideal for automotive applications like current measurement in traction motor and battery management systems. They are also well suited for use in 48V vehicle systems. Other applications include aerospace power management systems, three-phase solar inverters, industrial motor controls and other applications requiring high isolation between the sense and output windings.

The CST2020 Series is available with four turns ratios ranging from 1:70 to 1:300, and offers very low sense resistance (0.00084 Ohms).

As with all Coilcraft parts, free evaluation samples are available online at www.coilcraft.com. Parts are available from stock and can be ordered online at buy.coilcraft.com or by calling Coilcraft sales.

For more information about the CST2020 Series, contact Len Crane, +1-847-639-6400, lcrane@coilcraft.com.

About Coilcraft

Headquartered outside of Chicago in Cary, Illinois, Coilcraft is a leading global supplier of magnetic components including high performance RF chip inductors, power magnetics and filters. In addition to a large selection of standard components, Coilcraft also designs and builds custom magnetics to fit a customer’s exact electrical requirements.

Engineers and buyers consider Coilcraft a preferred supplier because of its reputation for quality, reliable delivery, engineering support and the superior performance of our products. In independent surveys, engineers consistently rank Coilcraft the number one magnetics company they would recommend to a friend.

Coilcraft
1102 Silver Lake Road
Cary, IL 60013 USA
+1-847-639-6400
Fax +1-847-639-1469

Selecting the best inductor for a DC/DC converter

BY LEN CRANE,
Director of Technical Marketing
Coilcraft, Inc.
www.coilcraft.com 

Courtesy of www.electronicproducts.com

While DC/DC conversion circuitry has matured to the point that there are “cookbook” design aids as well as software to help, selecting the right power inductor is a critical aspect of converter design. This requires a good understanding of inductor performance and of how desired in-circuit performance relates to the information available in supplier data sheets.

Inductors that can be used in DC/DC converters come in a wide variety of shapes and sizes (Fig. 1). In order to compare types and choose the optimal part for the application, a designer must rely on correctly understanding published specifications.

1117_Special_Passives_Coilcraft-Fig-1

Fig. 1: Inductors come in many shapes and sizes: Thin versions enable low-profile converter designs.

Inductor performance can be described by relatively few numbers. A typical data sheet excerpt for a surface-mount power inductor intended for DC/DC converters is shown (Table 1).

Table 1: Typical data sheet excerpt for a surface-mount power inductor.

Part number L ±20% (µH) DCR max (mΩ) SRF typ (MHz) Isat (A) Irms (A)
XAL4020-102 1.0 14.6 79 8.7 9.6

Inductance: Per Table 1, the inductance (L) is the main parameter that provides the desired circuit function and is the first parameter to be calculated in most design procedures. It is calculated to provide a certain minimum amount of energy storage (or volt-microsecond capacity) and to reduce output current ripple. Using less than the calculated inductance causes increased AC ripple on the DC output. Using much greater or much less inductance may force the converter to change between continuous and discontinuous modes of operation.

Because it is not practical for a data sheet to show performance for all possible sets of operating conditions, it is important to have some understanding of how the ratings would change with different operating conditions.

Tolerance: Fortunately, most DC/DC converter applications do not require extremely tight tolerance inductors to achieve these goals. It is, as with most components, cost-effective to choose standard tolerance parts, and most converter requirements allow this. The inductor in Table 1 is shown specified at ±20%, which is suitable for most converter applications.

Test conditions: These are critical, and designers need to pay special attention to voltage, wave shape, and test frequency. For example, most catalog inductance ratings are based on “small” sinusoidal voltages, and the use of sinusoidal voltage is a standard instrumentation test condition. With regard to frequency, most power inductors do not vary dramatically between 20 kHz and 500 kHz, so a rating based on 100 kHz is quite often used and suitable. However, inductance eventually decreases as frequency increases. As switching frequencies increase to 500 kHz, 1 MHz, and above, it becomes more important to consider ratings based on the actual application frequency.

DC resistance (DCR): This is based strictly on the wire diameter and length and is specified as a “max” in the catalog but can also be specified as nominal with a tolerance. DCR varies with temperature, so it is important that the DCR rating also notes the ambient test temperature. The temperature coefficient of resistance for copper is approximately +0.4% per degree C. So the part shown rated at 0.009 Ω max would have to have a corresponding rating of 0.011 Ω max at 85°C — only a 2-mΩ difference in this case, but a total change of about 25%. The expected DCR versus temperature is shown (Fig. 2).

1117_Special_Passives_Coilcraft-Fig-2

Fig. 2: Expected DCR versus temperature curve based on 0.009 Ω max at 25°C.

AC resistance: This is not commonly shown on inductor data sheets and is not typically a concern unless either the operating frequency or the AC component of the current is large with respect to the DC component.

When trying to minimize the size of the component, the designer should try to select the part with the largest possible resistance. Typically, to reduce the DCR means having to use larger wire and probably a larger overall size. So optimizing the DCR selection means a tradeoff of power efficiency, allowable voltage drop across the component, and component size.

Self-resonant frequency (SRF): Every inductor winding has some associated distributed capacitance, which, along with the inductance, forms a parallel resonant tank circuit with a natural self-resonant frequency. For most converters, it is best to operate the inductors at frequencies well below the SRF. This is usually shown in the inductor data as a “typical” value.

Current rating: This is perhaps the rating that causes the most difficulty when specifying a power inductor. Current through a DC/DC converter inductor is always changing throughout the switching cycle and may change from cycle to cycle depending on converter operation, including temporary transients or spikes due to abrupt load or line changes. This gives a constantly changing current value with a sometimes very high peak-to-average ratio. It is the peak-to-average ratio that makes specification difficult. Look for an inductor that has two current ratings: one to deal with possible core saturation from the peak current and one to address the heating that can occur due to the average current.

Saturation current (Isat): One effect of current through an inductor is core saturation. Frequently, DC/DC converters have current wave shapes with a DC component. The DC current through an inductor biases the core and can cause it to become saturated with magnetic flux. The designer needs to understand that when this occurs, the inductance drops and the component no longer functions as an inductor. A typical L versus current curve for a gapped ferrite core is shown (Fig. 3).

1117_Special_Passives_Coilcraft-Fig-3

Fig. 3: A typical L versus DC bias current curve for a gapped ferrite core showing the point of current saturation.

It can be seen that this curve has a “knee” as the inductor moves into the saturation region. Definition of where saturation begins is, therefore, somewhat arbitrary and must be defined. In the example of Table 1, saturation is defined at the point at which the inductance drops by 10%. Definitions in the range of 10% to 20% are common, but it should be noted that some inductor catalogs might use figures of 50% inductance drop. This increases the current rating but may be misleading as far as the usable range of current is concerned.

While there is more to be said on this topic, suffice it to say that it is typically desirable to operate with current peaks near the saturation rating because this allows the smallest possible inductor to be chosen.

RMS current (Irms): The second major effect of current is component self-heating. The Irms is used to give a measure of how much average current can continuously flow through the part while producing less than some specified temperature rise. In this case, the data sheets usually provide a rating based on application of DC or low-frequency AC current, so this does not include heating that may occur due to skin effect or other high-frequency effects. The current rating may be shown for a single temperature rise point as in the example, or some suppliers provide helpful graphs of temperature rise versus current or factors that can be used to calculate temperature rise for any current.

Temperature rise due to self-heating may cause the inductor to be at a temperature higher than the rated range. This is normally acceptable provided that the insulation ratings are not exceeded.

As with other parameters, it is important to know the inductor temperature rise so that this can be traded off with other parameters when making design choices. If lower temperature rise is desired, a larger size component is most likely the answer.

Conclusion
It can be seen that inductors for DC/DC converters can be described by a small number of parameters. However, each rating may be thought of as a “snapshot” based on one set of operating conditions that may need to be augmented to completely describe expected performance in application conditions.

Learn more about Coilcraft

Coilcraft Releases Two New Power Inductors with Specialized Terminations

Courtesy of Coilcraft

For Editorial Use:
English Word Document
Image
Coilcraft Press Room

Cary, IL, USA — Coilcraft announces the introduction of two new products to its line of high current, molded power inductors, both offering unique termination options.

Coilcraft_0805HP_Photo_webThe XTL7030 Series features side metal terminations for automated optical inspection (AOI) of the component during the solder reflow process. It offers inductance values from 10 to 47 µH – significantly higher than products currently available from other manufacturers in the same size part. It also provides excellent current handling (up to 5.3 Amps) and exceptionally low AC + DC power losses for greater efficiency.

XTL7030 inductors measure just 7.1 mm square, with a maximum height of 3.2 mm. They feature RoHS compliant tin-silver over copper terminations and are halogen free. They are also qualified to AEC-Q200 Grade 1 standards (-40° to +125°C ambient), making them suitable for automotive and other harsh-environment applications.

The XAR7030 Series marks the first time raised inductors are available as standard, off-the-shelf products. They measure 8.5 mm square, with terminals that elevate the inductor body 1.5 mm from the printed circuit board surface. The unique off-the-board construction allows standard power management IC packages (e.g., QFN/VQFN) to be mounted beneath the inductor in a 3-D packaging arrangement, reducing overall board space. The XAR7030 is available with inductance values ranging from 0.16 to 10 µH. It also offers extremely low DCR – as low as 1.26 mOhms. It features RoHS compliant matte tin over nickel over phos bronze terminations and is also halogen free. Contact Coilcraft to discuss raised inductors in other sizes.

The composite construction of both products results in soft saturation characteristics, allowing them to withstand high current spikes. They exhibit no thermal aging issues, and their construction also minimizes audible buzzing.

Like all Coilcraft products, complete technical specifications and free evaluation samples of the XTL7030 and XAR7030 Series are available online at www.coilcraft.com. Parts are available from stock and can be purchased direct at buy.coilcraft.com or by calling a local Coilcraft sales office.

For more information, contact Len Crane, +1-847-639-6400, lcrane@coilcraft.com

About Coilcraft

Headquartered outside of Chicago in Cary, Illinois, Coilcraft is a leading global supplier of magnetic components including high performance RF chip inductors, power magnetics and filters. In addition to a large selection of standard components, Coilcraft also designs and builds custom magnetics to fit a customer’s exact electrical requirements.

Engineers and buyers consider Coilcraft a preferred supplier because of its reputation for quality, reliable delivery, engineering support and the superior performance of our products. In independent surveys, engineers consistently rank Coilcraft the number one magnetics company they would recommend to a friend.

Coilcraft
1102 Silver Lake Road
Cary, IL 60013 USA
+1-847-639-6400
Fax +1-847-639-1469

New Ceramic Chip Inductors Provide the Industry’s Highest Q in an 0805 Package

Courtesy of Coilcraft

For Editorial Use:
English Word Document
Image
Coilcraft Press Room

Cary, IL, USA — Coilcraft’s new 0805HP Series ceramic wirewound chip inductors offer the industry’s highest Q factors in an 0805 size at frequencies up to 3 GHz. It is available with 23 inductance values ranging from 2.6 to 820 nH, with 2% tolerance available for most values.

Coilcraft_0805HP_Photo_webThe 0805HP Series features a wirewound construction for highest possible self resonance – up to 9.5 GHz. It also offers significantly lower DCR (as low as 15 mΩ) than the previous generation products, making it appropriate for high current applications.

0805HP Series inductors feature RoHS compliant, silver-palladium-platinum-glass frit terminations and offer a maximum reflow temperature of 260°C. COTS Plus tin-silver-copper and tin-lead terminations are also available.

Like all Coilcraft products, complete technical specifications and free evaluation samples of the 0805HP Series are available at www.coilcraft.com. Parts are available from stock and can be ordered on-line at buy.coilcraft.com or by calling a local Coilcraft sales office.

For more information, contact Len Crane, +1-847-639-6400, lcrane@coilcraft.com

About Coilcraft

Headquartered outside of Chicago in Cary, Illinois, Coilcraft is a leading global supplier of magnetic components including high performance RF chip inductors, power magnetics and filters. In addition to a large selection of standard components, Coilcraft also designs and builds custom magnetics to fit a customer’s exact electrical requirements.

Engineers and buyers consider Coilcraft a preferred supplier because of its reputation for quality, reliable delivery, engineering support and the superior performance of our products. In independent surveys, engineers consistently rank Coilcraft the number one magnetics company they would recommend to a friend.

Coilcraft
1102 Silver Lake Road
Cary, IL 60013 USA
+1-847-639-6400
Fax +1-847-639-1469

Key Parameters for Selecting RF Inductors

Courtesy of Coilcraft

Understanding RF Inductor Specifications

RF inductor selection involves these key parameters: mounting (surface mount or through-hole), inductance value, current rating, DC resistance (DCR), self-resonant frequency (SRF), Q factor, and temperature rating. While small size is typically desired, the laws of physics limit how small an inductor can be for a given application. Inductance value and current rating are the chief determinants of size; other parameters can then be optimized.

Read full article here: www.coilcraft.com/pdfs/doc671_Selecting_RF_Inductors.pdf

New Wirewound Chip Inductors Provide the Highest Inductance in the Industry’s Smallest Package

New Wirewound Chip InductorsCary, IL, USA — Coilcraft has introduced its new 0201HL Series of chip inductors available in seven inductance values ranging from 22 to 51 nH, the highest currently offered in a wirewound 0201 package. This inductance range is fully optimized for impedance matching in 700 MHz LTE and 5G applications.The 0201HL Series also provides the highest Q factors currently available in that package size – up to 62 at 2.4 GHz. These Q factors are twice as high those available with thin-film, multilayer technology. It offers SRF values as high as 4.35 GHz, DCR as low as 0.75 Ohms, and Irms as high as 140 mA.

0201HL Series inductors are also RoHS compliant and halogen free, and feature matte tin over molybdenum-manganese terminations.

Like all Coilcraft products, complete technical specifications and free evaluation samples of the 0201HL Series are available at www.coilcraft.com. Parts are available from stock and can be ordered on-line at buy.coilcraft.com or by calling a local Coilcraft sales office.

For more information, contact Len Crane, +1-847-639-6400, lcrane@coilcraft.com

About Coilcraft

Headquartered outside of Chicago in Cary, Illinois, Coilcraft is a leading global supplier of magnetic components including high performance RF chip inductors, power magnetics and filters. In addition to a large selection of standard components, Coilcraft also designs and builds custom magnetics to fit a customer’s exact electrical requirements.

Engineers and buyers consider Coilcraft a preferred supplier because of its reputation for quality, reliable delivery, engineering support and the superior performance of our products. In independent surveys, engineers consistently rank Coilcraft the number one magnetics company they would recommend to a friend.

Coilcraft
1102 Silver Lake Road
Cary, IL 60013 USA
+1-847-639-6400
Fax +1-847-639-1469

Courtesy of CoilcraftView more here: www.ezwire.com

For Editorial Use:
Word Documents :
English |  German |  Korean |
Simplified Chinese |  Japanese
High Resolution Images :
1 | 2
Coilcraft Press Room

New Coilcraft Automotive-grade Power Inductors Offer Superior Performance in a Compact Package

Courtesy of Coilcraft

Cary, IL, USA — Coilcraft’s new SRT8045 Series of magnetically shielded power inductors offer superior performance and a smaller package than previous-generation products. Measuring just 8.0 x 8.4 x 4.5 mm, the highly cost-effective SRT8045 has saturation current ratings up to 17.4 Amps and DC resistance as low as 7.7 mΩ, allowing users to dramatically reduce inductor size while maintaining excellent performance.

SRT8045 Series inductors are offered in five inductance values ranging from 1.4 to 22 µH. They are qualified to AEC-Q200 Grade 1 standards (-40° to +125°C ambient), making them suitable for automotive and other harsh-environment applications. They feature RoHS compliant, matte tin over nickel over phos bronze terminations and offer a maximum reflow temperature of 260°C. COTS Plus tin-silver-copper and tin-lead terminations are also available.

As with all Coilcraft parts, free evaluation samples of the SRT8045 Series are available online at http://www.coilcraft.com/srt8045.cfm. For more information, contact Len Crane, +1-847-639-6400, lcrane@coilcraft.com

About Coilcraft

Headquartered outside of Chicago in Cary, Illinois, Coilcraft is a leading global supplier of magnetic components including high performance RF chip inductors, power magnetics and filters. In addition to a large selection of standard components, Coilcraft also designs and builds custom magnetics to fit a customer’s exact electrical requirements.

Engineers and buyers consider Coilcraft a preferred supplier because of its reputation for quality, reliable delivery, engineering support and the superior performance of our products. In independent surveys, engineers consistently rank Coilcraft the number one magnetics company they would recommend to a friend.

Coilcraft
1102 Silver Lake Road
Cary, IL 60013 USA
+1-847-639-6400
Fax +1-847-639-1469

Please view Press Release here: www.ezwire.com

Choosing Inductors for Energy Efficient Power Applications

Energy efficiency can be as much about the inductors as the circuit topology.

In high frequency DC-DC converters, inductors filter out the AC ripple current superimposed on the DC output. Whether the converter steps the voltage down – buck – or steps the voltage up – boost – or both up and down – SEPIC, the inductor smooths the ripple to provide a pseudo-DC output.

For battery powered applications, battery life is extended by improving the efficiency of the entire power supply circuit, and inductor efficiency is often a major consideration in the design. Careful consideration of inductor efficiency can mean the difference between having your battery work when you need it and having to stop in the middle of an important task to plug it into a charger.

Inductor efficiency is highest when the combination of core and winding losses are the lowest. Therefore, the goal of highest efficiency is met by selecting an inductor that provides sufficient inductance to smooth out the ripple current while simultaneously minimizing losses. The inductor must pass the current without saturating the core or over-heating the winding.

Accurately predicting core and winding loss of an inductor can be fairly complicated. Core loss depends on several factors, such as peak-peak ripple current, ripple current frequency, core material, core size, and turn count. The required ripple current and ripple current frequency are application-dependent, while the core material, core size, and turn count are inductor-dependent.

Download PDF here: www.coilcraft.com

Coilcraft’s New Power Inductor Selection Tool Provides Significantly More Performance Data

Cary, IL, USA — Coilcraft has launched a new suite of Power Inductor Selection Tools that allows users to easily select the appropriate path for their particular search while also providing more application-specific performance data than previously available on any industry site.

XEL60xxLen Crane, Coilcraft’s Director of Technical Marketing, will be previewing the tool this week at the Applied Power Electronics Conference (APEC 2017) in Tampa, Florida. Mr. Crane’s exhibitor seminar, titled “New Power Inductor Selection Process for Best Power Converter Performance,” will be held Wednesday (3/29) at 10:30 A.M. in Room 13.

Entering the new tool, users are offered four paths depending on whether they need inductors for a known converter topology, a specific IC they want to use, an existing set of inductor specifications, or they simply want to compare inductors they have already chosen. Regardless of which path they take, the tool provides a complete list of off-the-shelf inductors that meet the defined specifications. The sortable results page includes standard datasheet performance specifications (e.g., inductance, Isat, Irms, temperature rating, and dimensions), as well as a variety of application-specific data such as DCR @ temperature, total losses and part temperature.

Users can now conduct deeper analysis by creating on-demand charts for up to six parts under actual operating conditions. These graphs include CCM and DCM waveforms, L vs. Ipeak Current, Temp Rise vs. Irms Current, Losses + Temperature Rise, Total Losses vs. Vin, and Total Losses vs. Frequency. Loss comparisons include Core + AC Winding loss and DCR loss. The tool also allows users to explore losses further with Losses vs. Ripple and Losses vs. Frequency graphs, which also highlight when parts exceed their maximum temperature rating.

The user experience of the new tool has been enhanced with the ability to move and delete columns, adjust the ambient temperature for dynamic results and filter parts by core material, part mounting, shielding and AEC qualification.

Users can access Coilcraft’s new Power Inductor Finder at: http://www.coilcraft.com/apps/power_tools/

For more information, contact Len Crane, +1-847-639-6400, lcrane@coilcraft.com

About Coilcraft

Headquartered outside of Chicago in Cary, Illinois, Coilcraft is a leading global supplier of magnetic components including high performance RF chip inductors, power magnetics and filters. In addition to a large selection of standard components, Coilcraft also designs and builds custom magnetics to fit a customer’s exact electrical requirements.

Engineers and buyers consider Coilcraft a preferred supplier because of its reputation for quality, reliable delivery, engineering support and the superior performance of our products. In independent surveys, engineers consistently rank Coilcraft the number one magnetics company they would recommend to a friend.

Coilcraft
1102 Silver Lake Road
Cary, IL 60013 USA
+1-847-639-6400
Fax +1-847-639-1469

www.coilcraft.com

Testing Aerospace

For nearly a decade, Coilcraft Critical Products & Services (CPS) has designed and built critical-grade components for use in military, aerospace, medical and other harsh-environment applications where durability and reliability are of paramount importance. To meet these demands, Coilcraft CPS tests components to extremes, far exceeding performance ratings of standard commercial parts. All components are manufactured, tested and certified by Coilcraft CPS without third-party alterations or testing, ensuring complete and documented control of all processes.

With hundreds of space missions under its belt, Coilcraft CPS is well positioned for all its clients’ aerospace applications. Leading aerospace companies rely on the company’s proven space-grade RF and power magnetic featuring:

  • Custom termination plating including Sn/Pb and gold
  • Extended temperature ranges (-55°C to +300°C)
  • Vibration testing to 80 g / shock testing to 1,000 g
  • Low outgassing to NASA specifications
  • ESCC qualified (Level 2) components
  • QPL applied

Coilcraft CPS also offers comprehensive product testing and validation services in accordance with established industry standards, as well as custom screening to cients’ electrical and physical specifications.


Visit Coilcraft at Space Tech Expo Europe 2017 in stand E92

Courtesy of www.spacetechexpo.eu