Product roundup: Inductors and transformers

Like many passive component markets, magnetic component manufacturers face challenges in shrinking component size and weight while also delivering higher performance. Inductors and transformers are used across a broad range of applications, but two industries driving some of the biggest innovations are automotive and industrial as their usage grows in these markets.

High-reliability markets like automotive and industrial have a unique set of requirements. They need components that can withstand harsh environments, operate over extended temperature ranges and deliver high stability and long life. Inductor and transformer manufacturers continue to focus on new techniques and materials to drive higher performance as well as reduce the size and weight of the devices.

Key improvements for inductors include lower DC resistance (DCR), lower losses and a wider operating temperature range in smaller packages. For transformers, the focus is higher isolation, lower losses, improved heat dissipation and higher operating temperatures in a smaller footprint. They are also starting to address wide-bandgap (WBG) device switching.

Over the past year, magnetic component manufacturers have addressed growing demand in automotive and industrial applications with advances in both inductors and transformers. They have also developed combo devices that integrate inductors and transformers in the same package. Here are a few examples of the latest advances in inductors and transformers for automotive and industrial applications.

Inductors

Power inductors are a big market for automotive, particularly for electric vehicles and autonomous driving (AD). With increasing demands to save weight and space, along with delivering high reliability and withstanding harsh environments, inductor manufacturers are developing new designs to meet these requirements.

One of Bourns Inc.’s most recent product line expansions includes its semi-shielded power inductors. These five automotive-grade power inductors come with enhanced mechanical strength and stability. The AEC-Q200–compliant model series includes the SRN2010BTA, SRN2510BTA, SRN3010BTA, SRN3012BTA and SRN3015BTA Series. They offer enhanced reliability thanks to their bottom-soldered lead-wire construction that provides increased mechanical strength and stability.

They combine the feature benefits of both non-shielded and shielded inductors, Bourns said, which provides lower magnetic field radiation compared with non-shielded inductors and a more cost-effective alternative to fully shielded ferrite-based inductors.

The power inductor series is available in a wide range of inductance ratings with a 20% tolerance. They also offer multiple footprints with a 1-mm max profile. The operating temperature range is –55°C to 125°C. The inductors are manufactured with a ferrite core and enameled copper wire.

Applications include differential choke power-conversion solutions for automotive systems, as well as DC/DC converters and power supplies in consumer, industrial and telecom electronics that require high reliability. The new semi-shielded power inductor series is RoHS-compliant and halogen-free.

Taiyo Yuden Co. Ltd. expanded its family of metal power inductors with an extended operating temperature range and low DCR. The company added seven devices in two sizes to its MCOIL LCCN series of multi-layer metal power inductors. These include the LCCNF1608KKTR24MAD, LCCNF1608KKTR33MAD and LCCNF1608KKTR47MAD inductors in a 1.6 × 0.8 × 1.0-mm package size. Four additional devices—the LCCNF2012KKTR24MAD, LCCNF2012KKTR33MAD, LCCNF2012KKTR47MAD and LCCNF2012KKT1R0MAD—are available in a 2.0 × 1.25 × 1.0-mm package.

The AEC-Q200–qualified LCCN series was developed in part to meet the increasing demand for more power supply circuits in automotive system applications. The LCCN series is based on the MCOIL LSCN series inductors, which use a multi-layer structure that enables the development of smaller, thinner products. This is particularly advantageous as more electronics components are integrated into modules for automotive systems, the company said.

The new power inductors are designed as choke coils in power supply circuits for automotive body and information systems like instrument clusters and infotainment devices. The new LCCNF1608KKTR24MAD power inductor, as an example, offers a wider operating temperature range of –55°C to 150°C. The LCCNF1608KKTR24MAD is also said to offer industry-leading DC superposition characteristics (saturation current at 3.2 A max) and low DCR (35 mΩ max) while maintaining the compact size of the MCOIL LSCN series.

TDK Corp. offers its high-reliability CLT32 series of power inductors for advanced driver-assistance systems (ADAS) and AD power management ICs (PMICs) and DC/DC converters with high clock rates. These nine devices deliver high-performance electrical values in a small package thanks to a new design.

The nine devices in the series cover an inductance range of 17 nH to 440 nH and offer a high saturation current of up to 60 A (13.5 A to 60 A). The operating temperature range is –40°C to 165°C, including self-heating. The devices are packaged in a 3.2 × 2.5-mm footprint with an insertion height of 2.5 mm. TDK said they are the “most compact SMT power inductors in their performance class.”

These AEC-Q200–certified inductors are designed with a solid copper coil over-molded with a ferromagnetic plastic compound. Thanks to the solid copper coil, these devices can achieve an exceptionally low DCR value, keeping losses to a minimum, TDK said. The ohmic resistance is 0.39 mΩ at an inductance value of 17 nH.

In addition, the coil ends function as terminals, which significantly increase reliability, particularly for automotive applications, TDK said. The high reliability is due to the design with no internal connections and the thick copper structure.

These devices are suited for safety-critical automotive applications that use high-performance processors, which require currents in the double-digit ampere range. PMICs are used as power supplies to provide these high currents, which use power inductors for stabilization at the outputs, TDK said. The CLT32 series can handle switching frequencies of up to 10 MHz.

Samsung Electro-Mechanics recently announced that it will begin mass production of power inductors for EV cameras with AD systems. It is the first time that the company is mass-producing automotive power inductors. The first AEC-Q200–qualified devices are power inductors in a 2016 size (2.0 × 1.6 mm) with inductance ratings of 1.0 µH and 2.2 µH.

“The performance of a power inductor is generally determined by the raw materials, magnetic substances [objects with magnetic properties] and the number of coils [copper wires] that can be wound inside,” Samsung said, which means improving the performance of the power inductor requires improvements in the properties of the magnetic substances and more coils wound in the limited space.

Samsung’s power inductor design features thin coils formed on the package substrates, which deliver higher productivity and miniaturization than the wire-wound type wherein the coils are wound on magnetic substances.

The magnetic substances are reported to offer excellent properties and low losses based on the materials technology gained through Samsung’s MLCC manufacturing expertise, together with the photosensitization method (a method of engraving circuits using light) used in semiconductor package substrates to precisely form coils with tiny spacing.

Vishay Intertechnology Inc. launched its first AEC-Q200–qualified IHSR high-temperature inductor last year. The inductor offers current ratings up to 155 A in the 6767 case size (19 × 17.1 × 7.0 mm). These inductors are used for multi-phase, high-current power supplies and input/output filters in automotive under-the-hood and ADAS applications.

The Vishay Dale IHSR-6767GZ-5A offers a 50% reduction in DCR over typical power inductors and a smaller size than similar, ferrite-based solutions, Vishay said.

The high-temperature inductor is optimized for energy storage in DC/DC converters up to 5 MHz and high-current filtering applications. With its high operating temperature up to 155°C, the device is also suited for filtering and DC/DC conversion in ADAS and LiDAR microprocessors, 12-V/48-V vacuumless braking systems, on-board chargers (OBCs) and brushless DC electric motors up to 140 A.

“For these applications, the IHSR-6767GZ-5A’s low typical DCR of 0.24 mΩ and inductance of 0.22 µH allow for higher current density than competing technologies, with no hard saturation and more stable inductance and saturation over the entire operating temperature range,” Vishay said.

ITG Electronics launched a line of “Mega Power” high-current, flat-wire inductors for industrial and rugged environments, including automotive applications. Said to offer higher power ratings compared with conventional flat-wire inductors, these devices feature denser magnetic materials, allowing for custom-level power in a standardized product.

One example cited is the ITG L201316Q, which offers an inductance range from 1.00 H to 105 µH and high-power capabilities of 11.6 µH/75 A and 105 µH/25 A. This is said to represent 2× to 4× the power capabilities offered by competitive products. The L201316Q is an alloy powder–based DIP inductor with lower core loss and no thermal aging concerns. The operating temperature range is –55°C to 150°C. Custom designs are available for the AEC-Q200–compliant inductors.

Transformers

The size of transformers continues to be a challenge in many applications. At the same time, they need to address efficiency, power density and heat dissipation.

Bourns, for example, has addressed these issues with its Model PLN0xx-ED21 Series planar transformers in a compact, low-height profile design. Developed for high-frequency and compact power-conversion application requirements, these forward-converter transformers offer high volumetric power density, low loss and high efficiency.

Bourns said planar transformers increase design flexibility and offer efficiency and power density advantages over conventional wire-wound transformer designs thanks to their significantly reduced AC resistance losses. This new series also offers greater reliability due to its enhanced thermal-conduction and heat-dissipation properties.

Key specs include 48 W up to 70 W of output power in applications with input voltages ranging from 33 to 57 VDC, a switching frequency of 250 kHz, low leakage inductance from 0.29 μH to 0.60 μH and a volt-second time of 81.6 V-µs. The devices also provide a 33- to 57-V input voltage and 5- to 12-V output voltage at 4-A to 14-A output with various turns ratios.

These features and their small design make the PLN0xx-ED21 planar transformers suited for power-conversion solutions for high-density industrial power systems, low-profile switch-mode power supplies, LED lighting applications, battery management systems and power-over-Ethernet applications. Custom requests are available.

Another space saver is TDK Corp.’s family of EPCOS E13EMHV SMT transformers with high dielectric strength for a range of DC/DC converter topologies. The isolation distances meet the IEC 60664-1 and IEC 61558-2-16 standards with a high working voltage of 1,000 VDC. They can handle transient overvoltages of up to 2,500 V_peak. The high dielectric strength between the primary and secondary sides is 3,000 VAC (50 Hz, 60 seconds).

The B78308*A003 series transformers save space with a footprint of 12.9 × 15.8 × 11.4 mm. Thanks to the internal construction of the transformers, they meet requirements for clearance and creepage distances according to the IEC 60664-1 standard (Np/Ns: min. 8.14-mm clearance, min. 11.2-mm creepage).

The transformers are available for a range of DC/DC converter topologies. Various turns ratios are available for the flyback topology and push-pull and half-bridge converters.

Other specs include a frequency range from 100 kHz to 500 kHz, a very low coupling capacitance of 2 pF and an operating temperature range from –40°C to 150°C. They are qualified to AEC-Q200 Rev. D and are suitable for a variety of DC/DC converter topologies and gate-driver circuits in e-mobility and industrial electronics applications.

With the growing usage of WBG technologies across industries, Pulse recently launched a 2-W LLC transformer for silicon carbide (SiC)/gallium nitride (GaN) drive applications. It is the company’s first LLC transformer specifically designed for SiC/GaN device switching.

The PMT6709NL delivers 2 W of power, which can be configured with LLC controllers like the TI UCC25800-Q1 or the MPS MPQ18913 to provide positive and negative outputs for robust switch-on/-off.

The new transformer features an extended creepage UI5 platform that provides 3.75-kVrms hi-pot isolation voltage in a compact (17.2 × 11 × 8.5 mm max) SMD platform. This IATF design is compatible with full winding automation to meet the high-reliability requirements in automotive applications.

Targeting applications like inverter motor drives that are driven by high-voltage batteries, this platform meets the 9.1-mm minimum creepage requirement of IEC 61558-1 for basic insulation and a working voltage up to 850 Vrms, or up to 450-Vrms working voltage for applications that require reinforced insulation. It uses a split bobbin to keep the interwinding capacitance to less than 2.5 pF, Pulse said. The PMT6907NL is also compliant with IEC 60664 for basic insulation and a repetitive peak voltage of up to 900 V_peak, based on the partial discharge method.

Pulse said the new design, using the two-section PMT6907 winding construction and LLC topology, solves the high interwinding capacitance seen in traditional flyback and push-pull topologies, which limits the benefits of SiC/GaN MOSFETs, including the higher switching frequency. In the new design, the higher leakage inductance does not impact efficiency because it can be used as part of the resonant circuit, the company added.

The key benefits include potentially eliminating the external resonant inductor, an order-of-magnitude reduction in the common-mode current injection through the bias transformer thanks to the lower capacitance, and a further reduction in electromagnetic interference noise due to the LLC soft switching.

Combo packages

Also developed for automotive and other high-reliability applications are devices that integrate both the transformer and inductor in one package for a more compact design. These resonant devices are said to save PCB space, simplify layouts and reduce the number of components that need to be mounted.

One example is Premo’s BCBM-11KW-004, an 11-kW LLC set with a combined transformer and resonance inductor, designed specifically for OBCs. These chargers are often integrated into the vehicle’s powertrain and require transformers to convert the AC power from external charging stations or home charging units into the DC power to charge the vehicle’s battery, the company said.

The triple 3.6-KW LLC set (suited for 400-V input) with transformer and resonance inductor is capable of handling up to 11 kW of power and is designed to minimize energy losses during the charging process, which helps to reduce the overall energy consumption of the charging system. Other key specs include a 14:15 turns ratio, main inductance value of 115 µH, a switching frequency of 98–150 KHz and an output voltage of 240–460 V/<14.7 Arms.

The device measures 158 × 98 × 38 cm and weighs 1,500 grams, making it suited for use in OBCs in EVs, where space is at a premium. The BCBM family also includes 4-kW, 7-kW and 22-kW solutions. This set can be customized according to customer requirements.

Vishay Intertechnology Inc. also offers a resonant transformer for LLC applications that combines both the transformer and an integrated inductor in a single package. The 5.5-kW Vishay Custom Magnetics MRTI5R5EZ offers fully tunable magnetizing and leakage inductance with minimal parasitic variation, the company said.

When introduced in November 2022, Vishay said the MRTI5R5EZ was the first transformer of its kind to use a second middle transformer leg to complete the resonant inductor of the circuit, compared with other implementations that require an additional magnetic core to deliver the same performance.

This solution saves space and simplifies designs by eliminating the need for interconnects or jumpers from the resonant inductor to the transformer’s winding, Vishay said.

Key specs include operating frequencies from 100 kHz to 350 kHz, rated power from 4 kW to 6 kW with 400-V to 800-V input voltage and rated current to 28 A. The isolation voltage rating is 2,500 V. Other features include a bracket for cold-plate mounting with raised bosses, flush-mount options and standard M4 ring terminals for the transformer, with customizable lead lengths and terminal types. The device can be provided with a thermal gap pad on the mounting surface.

Applications include OBCs and half-/full-bridge resonant power supply transformers in industrial controls and solar inverters, as well as military, avionics and construction equipment. Customizable turns ratios are available for these applications, and the transformer’s losses can be moved from the core to the coil as needed to optimize performance and heat dissipation, Vishay said. It is also reported to offer minimal parasitic variation, which optimizes capacitor selection.