Top 10 inductors and transformers meet new requirement challenges

Magnetic components, like inductors and transformers, are used across a broad range of applications. As energy efficiency becomes a prime directive across industries, together with new industry standards, the need for inductors and transformers also increases, driving changes in size and packaging as well as industry-specific requirements. Depending on the device and application, these requirements include wide operating temperature ranges, high-current capabilities, and smaller packages.

There is a continued focus in the inductor and transformer markets on packing higher performance in smaller footprints as OEM designers face challenges in saving space and weight. For inductors, this also means delivering lower DC resistance (DCR), low electromagnetic interference (EMI), and high stability over a wider operating temperature range. For transformers, it translates into higher isolation and higher operating temperatures in a smaller footprint.

In addition, over the past year, magnetic component manufacturers have addressed growing demand in a variety of applications from power over coax (PoC) in automotive for inductors to power over Ethernet (PoE) for surface-mount transformers. Many of these new devices feature innovative construction and design to help achieve performance enhancements. Here are 10 inductors and transformers introduced over the past year that meet these growing trends.

Inductors

As automotive designers are faced with increasing demands to save weight and space, inductor manufacturers are developing new devices for automotive PoC systems that enable power and data transmission over the same cable.

TDK Corp. recently launched its ADL3225VM high-current inductors in a 3225 (3.2 × 2.5 × 2.5 mm) package size for PoC systems. The inductors reportedly achieve the highest-rated current in the 3225 package size. In addition, the proprietary structural design and wire-winding manufacturing process delivers high impedance over a broad bandpass frequency of 1 MHz up to 1 GHz, said the company.

The AEC-Q200 inductors target PoC in advanced driver-assistance system (ADAS) camera system circuits. “Performance advancements of ADAS applications have resulted in the increased production of electric control units, particularly around view cameras and front-sensing cameras, escalating the need for high-speed interfaces,” said TDK. “Low-voltage differential signaling with transmission rates of up to 1.5 Gbits/s transfer image signals from automotive cameras to the control circuit board. This process involves PoC systems that relay data and power over the same coaxial cable.”

 

The ADL3225VM-2R2M-TL000 and ADL3225VM-150M-TL000 inductors provide an inductance of 2.2 μH and 15 μH, respectively, both with a ±20% tolerance. The DC resistance (max) ratings for the ADL3225VM-2R2M-TL000 and ADL3225VM-150M-TL000 are 0.18 Ω (180 mΩ) and 0.40 Ω (400 mΩ), respectively. The devices operate over a temperature range of –55°C and 155°C. Rated current for the ADL3225VM-2R2M-TL000 and ADL3225VM-150M-TL000 are 1.22 A (40°C rise) and 725 mA (40°C rise), respectively.

Murata Electronics also recently introduced a series of inductors that target automotive PoC systems. The company’s new LQW43FT series of broadband inductors come in an 1812 package, claimed as the industry’s smallest inductor for bias-T circuits that supports an inductance range of 10 μH to 22 μH and high current of 700 mA.

The LQW43FT series is comprised of three models that deliver high impedance over a broad range to reduce the number of required inductors. Target applications include PoC systems used in serializer/deserializer interfaces.

Murata said the demand for PoC cables capable of carrying both signals and power is on the rise, with the increased adoption of self-driving applications such as ADAS.

Typically, multiple inductors are combined to form a broadband and high-impedance filter. These broadband inductors leverage Murata’s proprietary material and coil structure technologies to provide high performance in the low-frequency band up to 100 MHz. They can be used in combination with existing solutions to further reduce the number of parts and mounting space required for PoC, said Murata.

For electric vehicle (EV) applications, Vishay Intertechnology, Inc. has released two new automotive-grade IHTH high-current, high-temperature, through-hole inductors in the compact 1500 case size. The Vishay Dale IHTH-1500MZ-5A, with an inductance range of 0.47 µH to 4.7 µH, delivers high saturation current of 156 A and very low typical DCR down to 0.19 mΩ (0.19 to 1.13 µH), while the IHTH-1500TZ-5A, with an inductance range of 6.8 µH to 100 µH, offers saturation current of 106 A and typical DCR down to 1.1 mΩ (1.1 to 21.5 µH).

Based on IHLP technology, the shielded, composite construction of the devices enables a compact size of 38.1 × 38.1 × 19.81 mm. This allows the IHTH-1500MZ-5A and IHTH-1500TZ-5A to replace much larger and more expensive competing solutions in high-current filters for 12-V/48-V hybrid EV and mild-hybrid-EV output converters, as well as off-road diesel-injection drivers, catalytic pulse-width–modulation heaters, and electrical motors, said Vishay.

Both inductors handle high-transient–current spikes without hard saturation and offer “excellent” temperature conductivity via their housing, said Vishay. They also offer continuous high-temperature operation to 155°C and are RoHS-compliant, halogen-free, and Vishay Green. The devices also provide high resistance to thermal shock, moisture, and mechanical shock.

Another through-hole inductor comes from Gowanda Electronics. The new 28MG inductor series of non-magnetic RF through-hole (leaded) inductors is designed to address the market need for non-magnetic inductors that can achieve inductance values of up to 18 µH.

The 28MG series targets medical imaging equipment and other applications in which magnetic materials must be avoided, including use in telecommunications, security systems, instrumentation, laboratory analysis equipment, aviation equipment, navigation equipment, and electronic test equipment.

The 28MG series consists of 60 discrete parts with an inductance range from 1.2 µH to 18 µH, a current range of 315 to 2,400 mA DC, and DCR from 0.079 to 4.15 Ω. All of Gowanda’s non-magnetic surface-mount and through-hole inductors, including the new 28MG series, provide relative permeability of ≤1.00003.

In the power market, Bourns, Inc. introduced a new inductor series that offers high inductance and a high Q value in a miniature size for RF signal processing and DC power line applications. The Model SRN2012T semi-shielded power inductor series features a wirewound construction on a ferrite core to offer high inductance and Q values. A magnetic-epoxy coating applied to the perimeter of the inductor winding provides enhanced shielding and lower magnetic field radiation compared with non-shielded options, said the company.

Other key features include high self-resonant frequency, low DCR in a compact size, and an operating temperature range of –40°C to 125°C. Together, these features make the Model SRN2012T inductors suited for RF signal processing, resonant circuits, decoupling and noise filters, and DC power line applications for audio headsets, true wireless stereo headsets, cable modems, set-top boxes, hard-disk drives, tablets, and various mobile electronic devices.

Bourns noted that lower DC resistance and high Q values of 13 to 15 are possible in these miniature (2 × 1.2 × 1.2 mm) power inductors due to the wirewound construction. “High Q values provide a high impedance at resonance in inductive-capacitive circuits and low loss at high-frequency operation,” said Bourns.

The Model SRN2012T power inductor series offers an inductance range of 1.0 µH to 22 µH. With saturation current up to 1,100 mA and rated current up to 1,300 mA, the power inductors are reported to maintain high inductance at a greater peak current to meet the requirements of common DC power line applications. The devices are RoHS-compliant and halogen-free.

Transformers

One focus area for transformer manufacturers over the past year was the development of improved isolation transformers. These devices are used for safety reasons, protecting equipment, devices, and people. They can be used in a broad range of applications.

One of the newest isolation transformers is the Bourns Model PAD00x-T764 isolation transformer series. These push-pull transformers help increase safety in serial communications applications by providing isolation from high-voltage hazards between systems.

These transformers, with a low 0.4-mm profile, simplify isolated power and serial communication signal integrity in CAN, RS-485, RS-422, RS-232, SPI, I2C, and lower-power LAN-based applications. Target applications include industrial automation, embedded solutions, AC motor drives, system integration, communication PHYs, smart metering, and other applications requiring low DC power.

The Model PAD00x-T764 series offers 3.1-kVAC withstanding voltage, which provides an isolation barrier from high-voltage hazards, such as high-voltage batteries. Construction includes a ferrite toroid core to help ensure a high coupling factor and improved efficiency, said Bourns. EMI performance is enhanced in the winding of the transformer, enabling reduced emissions.

The PAD00x-T764 series is compatible with Texas Instruments’ SN6501 and SN6506B, Maxim Integrated’s (now a subsidiary of Analog Devices Inc.) MAX253 and MAX845, Analog Devices’ ADM2485, and similar transformer drivers. The series offers a 3.3-V to 5-V input, 3.3-V to 10-V output, and up-to-250-mA output with various turns ratios. Modifications and customization are available. The transformers are RoHS-compliant and halogen-free.

Also providing a compact size is the PH9572 series of high-isolation gate-drive transformers from Pulse Electronics. The demand for compact, high-isolation transformers is growing with the proliferation of high-voltage battery packs in automotive and energy storage applications, said the company.

Featuring an EP7 platform, measuring 10 × 9 mm with an 11-mm height, a key feature of the PH9572 series is the two gate windings with up to 5-mm creepage between windings. The family offers up to 2,500-Vrms gate-to-gate and gate-to-drive isolation capability and 6 W of driver power.

The PH9572 series consists of two product lines that are differentiated by specific insulation and safety classes. These are the NL series, offering functional insulation and tested up to 500-VDC constant isolation capability and 1,500-Vrms dielectric strength, and the ANL series, providing basic insulation and tested up to 1,000-VDC constant isolation capability and 2,500-Vrms dielectric strength. The ANL series offers the large 5-mm creepage between the gate windings.

The compact footprint in combination with the continuous isolation capability make the NL and ANL transformers suited for industrial, renewable energy generation, and storage systems. They can also be used in automotive applications such as inverters, on-board chargers, DC/DC, and battery management systems.

For space-constrained applications, TDK released a family of surface-mount transformers that targets DC/DC converters and gate drivers in e-mobility and industrial electronics. The EPCOS E10 EM series of insulated SMT transformers are suited for a variety of DC/DC converter topologies and gate driver circuits (IGBTs).

The E10 EM series is comprised of four models with a basic insulation working voltage of 500 Vrms and reinforced insulation of 300 Vrms. The turns ratio is between 1:0.76 and 4:1, depending on the model. The operating temperature range is –40°C to 150°C. The series is RoHS-compliant.

The compact SMT transformers measure 11.7 × 13.15 × 11.35 mm, meeting clearance and creepage requirements in accordance with the IEC 60664-1 standard (Np/Ns: min. 5.5-mm clearance, min. 6-mm creepage), thanks to the internal construction of the transformers. The devices feature a manganese-zinc (MnZn) ferrite core, SMD gull-wing pins, triple-insulated wire, and non-conductive pick-and-place cap on top. The E10 EM SMT transformer, B78307A*A003, is qualified in accordance with AEC-Q200 Rev. D.

PoE is also a key target market for surface-mount transformers. Signal Transformer, a Bel group company, offers the SPoE series of surface-mount transformers for equipment or devices connecting to an Ethernet or enterprise network that uses Ethernet cables to receive power and digital data signals.

IoT expansion is creating high demand for network devices connecting to the internet via Ethernet cables, said Signal Transformer, resulting in increased PoE connectivity in the smart-home/smart-LED-lighting market.

The SPoE transformers offer a range of options and can be used in a variety of applications such as VoIP phones, IP cameras, wireless access points, IPTV decoders, network routers, smart-home appliances, smart LED lighting, health care, connected security cameras, wireless data systems, and information displays, as well as PoE switches, extenders, splitters, and injectors.

The SPoE transformers, featuring flyback topology, provide a 250-kHz operating switching frequency, an input voltage range from 9 V to 57 V, and dielectric strength of 1,500 Vrms. They are available in five power levels (3, 7, 10, 13, and 27 W) in three SMD platforms (EP7, EP10, and EP13). The operating temperature range is –40°C to 125°C.

For higher-power applications, Würth Elektronik has expanded its MID-POE transformer series to include PoE++. These SMT transformers are suitable for flyback or active-clamp-forward power supplies that comply with the IEEE 802.3bt (four-pair PoE, or 4PPoE, also known as PoE++) standard for higher-power applications. The 10 new transformers can provide an output power of up to 95 W.

The company has extended its MID-POE series for IEEE 802.3bt Type 3 (60 W) and Type 4 (90 W) devices. These transformers use the low-profile EFD20 and EFD25 packages and offer high power densities over a wide range of common PoE output voltages. Applications for the PoE transformers include video conferencing systems, automation control systems, and smart IP cameras. Customer-specific versions are available on request.