Roundup: Power inductors for high-temperature applications

Over the past year, power inductor manufacturers have been tackling some of the biggest challenges in high-temperature applications, particularly automotive. Many of the newest products are making improvements in efficiency, heat dissipation, and electromagnetic interference (EMI). This often translates into inductors that offer lower DC resistance (DCR), low EMI thanks to shielding, soft saturation, low core losses, and high stability over the operating temperature range.

In many cases, these inductors enable DC/DC converters or power supplies to achieve higher power efficiency. You’ll also find that all of them are AEC-Q200 certified and many feature a new construction that help deliver those improvements. Here is selection of the latest inductors introduced over the past year.

Bourns, Inc. has added nine new series to its SRP series of power inductors that meet high-current-density requirements for a variety of consumer electronics and high-temperature applications. These inductors feature a coil that is wound with either round or flat wire completely press-molded with an iron-based magnetic metal alloy powder core. This construction delivers magnetic shielding, high current capability, compact size, low buzz noise, and excellent temperature stability, said Bourns.

Model SRP1040VA and SRP6030VA inductors are built with a new metal alloy powder formulation and round enamel-coated copper wire. The company’s metal alloy powder formulation allows an elevated operating temperature of 180 °C (including self-heating). This makes these AEC-Q200 compliant inductors suited for many high-temperature environments and high-reliability designs that include LED lighting, DC/DC converters, and power supplies. The inductance ratings are available from 0.47 – 22 µH.

Model SRP4018FA series inductors also AEC-Q200 compliant, and uses a flat enamel-coated copper wire in a self-lead terminal construction that provides very low DC resistance, which means it dissipates less power during operation especially at higher current and switching frequencies, allowing a DC/DC converter to achieve higher power efficiency. This model series features an inductance range of 0.33 – 1.2 µH and an operating temperature range of -55°C to 155°C.

Models SRP1245C, SRP1265C, SRP3012C, SRP3020C, SRP5020C and SRP5030C also offer high inductance selection based on their round enamel-coated copper wire construction. These models are commercial-grade for high-volume consumer electronics applications when an AEC-Q200 compliant inductor is not required. These models feature an inductance range of 0.1 – 33 µH and an operating temperature range of -40°C to 125°C.

Bourns also expanded its shielded power inductor line with 11 low-resistance, high-saturation-current model series. The Model SRP0xxx series, with a low profile of less than 2 mm, features a metal alloy powder core and flat wire construction that delivers several benefits including low copper loss, DC resistance, and audible core noise as well as high current saturation. This shielded construction also produces low magnetic radiation, offering good EMI performance and excellent temperature stability, said Bourns.

The series also offers higher reliability thanks to the use of external laser welding between the wire and terminal, which eliminates potential mechanical stress on the solder joint from the high-pressure molding process, said Bourns. Another benefit is the alpha-winding construction, which enables a wider inductance range at a given form factor while maintaining a very low-height profile.

Applications for the new inductors include smartphones, tablet terminals, laptop computers, hard disk drives, solid-state drives, servers, voltage regulators, and compact power supply modules. These applications, because of their high current density, typically operate at higher temperatures due to increased heat production, which can lead to higher degradation rates.

However, Bourns’ inductors, by providing lower DC resistance, dissipate less power during operation, especially at higher current and switching frequencies. This enables a DC/DC converter or power supply to achieve higher power efficiency and meet application specifications, said the company.

For higher efficiency in automotive applications Vishay Intertechnology touts its smallest automotive-qualified IHLP inductors in a 1212-case size (3.3 x 3.3 mm). The low-profile (down to 1.0 mm) inductors are designed to save space in ADAS and sensor applications, and offer high operating temperatures up to 155°C for under-the-hood applications.

The Vishay Dale IHLP-1212AZ-5A, IHLP-1212BZ-A1, and IHLP-1212BZ-5A are AEC-Q200 qualified, and are optimized for energy storage in DC/DC converters up to 5 MHz.  They are designed for filtering and DC/DC conversion in ADAS, sensor, and entertainment/navigation systems, in addition to noise suppression for medium-current filter applications. They provide excellent noise attenuation in high-current filtering applications up to the SRF of the inductor, said Vishay.

Packaged in a 100% lead (Pb)-free shielded, composite construction, the IHLP-1212AZ-5A, IHLP-1212BZ-A1, and IHLP-1212BZ-5A also offer high resistance to thermal shock, moisture, and mechanical shock, and handle high transient current spikes without saturation. The devices are RoHS-compliant, halogen-free, and Vishay Green.

Also developed for higher efficiency is Kemet’s range of SMD-based composite metal power inductors for DC/DC converters used in a variety of devices such as notebook computers, tablets, servers, and HDTVs. The new devices are part of the METCOM series of inductors developed for more efficient DC-to-DC switching power supplies and other power applications that require EMI filtering.

The new METCOM inductors also increase the efficiency of power designs with a shielded construction that contains the magnetic flux within the inductor body. The shield improves EMI performance and eliminates interference with surrounding circuitry.

In addition, the composite metal core in these new devices offers high-current-saturation characteristics, which allow the inductors to maintain functionality during the large ripple currents typically found in modern power applications. High permeability enables low values of DC resistance (DCR), that significantly reduces self-heating during high-current operation, which increases system efficiency and lowers the need for thermal management.

The METCOM series is comprised of 102 devices that cover an inductance range from 0.10 µH to 47.00 µH and offer DCR values as low as 1.5 mΩ. The inductors can support currents up to 35.4 A and operating temperatures between −55°C and 155°C.

Earlier this year, Kemet introduced the MPXV series that enhances the METCOM range. The AEC-Q200 qualified metal composite power inductors for automotive applications claim best-in-class EMI shielding for low magnetic flux leakage and provide efficient power conversion. Applications include DC-to-DC switching power supplies for the growing number of electronic control units (ECUs) found in automotive systems.

The MPXV series is optimized for the automotive market for electronic systems that demand high efficiency, low self-heating, and low power losses. These inductors can operate at temperatures up to 155°C and feature low electrical noise allowing them to be used in all areas of the vehicle – including some of the most challenging operating environments found under the hood and in the powertrain.

The metal composite material is molded around the inductor coil core and acts as a shield for neighboring electronics from the magnetic flux that might otherwise cause interference in sensitive systems. They are available in a variety of industry-standard SMD footprints.

Coilcraft also expanded its portfolio of AEC-Q200 qualified inductors with the introduction of the XGL4030 Series of high-performance, molded power inductors and AGM2222 Series power inductors.

The XGL4030 power inductors offer up to 40% lower DCR than the previous best-in-class inductors as well as extremely low AC losses. This delivers the best overall efficiency over a wide range of AC ripple current, said Coilcraft. Target applications include DC/DC converters with switching frequencies ranging from hundreds of kHz to 5 MHz and above.

The XGL4030 offers an expanded inductance range, including 18 values from 0.13 to 12.0 µH, with current ratings up to 26.5 A and soft saturation characteristics. It also offers a 30% increase in Irms self-heating current, which allows the XGL4030 to operate much cooler than previous-generation components.

XGL4030 Series inductors are qualified to AEC-Q200 Grade 1 standards (-40° to 125°C ambient) with a maximum part operating temperature of 165°C and exhibit no thermal aging issues, according to the company, making them suitable for automotive and other harsh-environment applications. Other features include minimized audible buzzing, RoHS compliance, and halogen-free construction.

The high-efficiency AGM2222 power inductors target 48-V automotive applications. They offer current ratings up to 110 A and very low DCR in a package measuring 22 × 22 × 23 mm, a 73% volume reduction from previous-generation products. The significant improvement in power density makes the AGM2222 suited for high-current applications including automotive bi-directional 12 V – 48 V DC/DC converters, said Coilcraft.

The AGM2222 Series is available in 13 inductance values from 1.9 to 10 µH. It is qualified to AEC-Q200 Grade 1 (-40°C to 125°C ambient), targeting automotive and other high-temperature applications. Other features include soft saturation that is stable over temperature and enables high peak current handling, and magnetic shielding that reduces EMI at high switching frequencies.

Continuing with its expansion of AEC-Q200 qualified SMD inductors, Sumida recently launched  the CDEP13D**/T150 line of power inductors that handle high temperature and high currents. The magnetically-shielded inductor line consists of ten standard types and ten high-power types that all provide high temperature, high current, and high-insulation voltage.

The power inductors offer an inductance range from 0.8 to 22 µH, with saturation current of up to 32 amps. They can withstand a voltage of up to 120 VDC and operate over the full operating temperature range of -40°C to 150°C (including coil’s self-temperature rise). Both product families are qualified to the AEC-Q200 reliability test requirements.

The inductors’ manganese-zinc (Mn-Zn) ferrite core has high-magnetic permeability and low power losses at the higher switching frequencies now found in automotive power circuits, according to Sumida. In addition, high-frequency performance is further enhanced by the application of flat coil windings, which counteract “skin-effect” and lower DC resistance. Flat-coil windings also help significantly reduce device size, said the company.

The part geometry provides very effective magnetic shielding, which is of growing importance because of the push towards smaller, more densely-packed automotive circuits, said Sumida. Applications include LED headlight driver modules, adaptive driving beam, adaptive LED boards, daylight running light systems, pulse width dimming circuits, hybrid engine controls, and powertrain control modules.

Eaton also offers a portfolio of automotive-grade, high-current power inductors. Tested beyond AEC-Q200 Grade 1 requirements, the HCM1AV2 line is available in 10 standard sizes and printed-circuit-board (PCB) footprints from 4 mm to 22 mm.

The HCM1AV2 can withstand high vibration and shock conditions thanks to its molded construction. The advanced construction combined with high-grade materials also allows the power inductors to withstand high temperature and high humidity environments in many automotive electronic systems.

The power inductors feature high current capability up to 100 A, lower DCR, low EMI, high voltage isolation, low core losses, soft saturation (roll-off) and high stability across the operating temperature range. These features address the need for increased power conversion and filtering requirements in the transportation market.

The HCM1AV2 inductors are  AEC-Q200 Automotive Grade 1 compliant, with a maximum operating temperature range of -55°C to 155°C (ambient plus self-temperature rise).

Dual inductors

Inductor manufacturers are also developing dual inductors that save space and reduce component count. These devices also are AEC-Q200 certified and operate over a wider temperature range.

Vishay Intertechnology, Inc. offers a family of IHLD series dual inductors. One of the most recent introductions is an automotive-grade dual inductor in a 2525 case size. The Vishay Dale IHLD-2525GG-5A replaces two inductors in an automotive Class D audio amplifier with one device, reducing both board space and component count.

The high-current device also offers improved total harmonic distortion (THD) performance over other inductor types, and low coupling for minimal crosstalk between the integrated inductors.

Providing noise filtering in Class D amplifiers, the low-profile device consists of two IHLP inductors with operating temperatures up to 155°C in one compact package. The device is AEC-Q200 qualified.

The IHLD-2525GG-5A operates at higher carrier frequencies up to 2.1 MHz, delivers high efficiency with a typical DCR from 7.06 mΩ to 154 mΩ, and offers a wide range of inductance values from 1.0 µH to 22 µH. The device provides rated current to 13.0 A and handles high transient current spikes without saturation.

The dual inductor is packaged in a 100 % lead (Pb)-free shielded, composite construction that reduces buzz to ultra-low levels, said Vishay. It offers high resistance to thermal shock, moisture, and mechanical shock.

Another dual inductor line comes from TDK Corporation. The company recently expanded its range of dual inductors to include the new EPCOS series B82477D6*. The seven series cover an inductance range from 2 x 3.9 µH to 2 x 47 µH and are designed for maximum rated currents from 2.83 A to 7.05 A. A key feature of the inductors is the high saturation currents of up to 16.1 A, said TDK.

The AEC-Q200 certified magnetically shielded inductors measure 12.5 x 12.5 x 10.5 mm³ and are designed for a wide temperature range of -55°C to 150 °C. The inductors offer very high coupling factors of the two windings from 97 to 99 percent, depending on the type.

These dual inductors can be used as coupled inductors in single-ended primary inductance converter (SEPIC) or 1:1 transformers in flyback topologies as well as a common-mode inductor in power supply lines. The isolation voltage between the two windings is >500 V