The requirements presently placed on power inductors are in stark contrast to the traditional principles of inductors: SMD ferrite inductors were for a long time the most popular technology for currents greater than 1A. However, due to their very high and nonlinear saturation behavior and their relatively large footprint, experts began looking for new technologies – and developed composite power inductors.
These inductors for currents above 100A offer a wide array of technical benefits for use in power supplies and filter applications. The special manufacturing process consisting of pressed powdered iron results in inductors that come very close to the ideal image of an inductor in many sectors.
Since powdered iron has a high magnetic saturation flux density, which helps to minimize losses. This enables the production of inductors with a thinner core and thus more space for thicker copper windings. The low DC resistance and minimum core losses additionally lead to less heat generation.
The main advantage of powdered iron is its robust saturation behavior that prevents even brief current peaks causing a drop in inductance. And since this positive behavior does not rely on the ambient temperature and aging effects it allows reliable designs across a wide range of application. Furthermore, composite power inductors provide a magnetically shielded design for improving electromagnetic compatibility and reducing interferences.
Standard composite power inductors are available in case sizes 1212 (3x3mm) through to 8787 (22x22mm). Due to their design, currents above 100A are possible in very compact components. By using various powdered iron composites it is possible to design and implement specific customer requirements, e.g. high temperature up to 180°C or high frequency ranges up to 5MHz for
These SMD power inductors are predominantly used as storage chokes in DC-DC converters and as EMC filter chokes in various applications, especially in the automotive and industrial electronics sector.
LED driver circuits are available in several topologies, e.g. Buck, Boost, Buck-Boost, and SEPIC design. The extensive range of applications includes interior and exterior automotive lighting, traffic and railroad signals, illumination, personal flashlights, and LCD panel backlights.
Practically, all of the said applications can benefit from the space savings delivered by Vishay's low-profile IHLP inductor series. The dimensions of the smallest type IHLP1212AB, for an inductance range of between 0.22µH and 100µH, and the largest type IHLP8787MZ are 3x3x1.2mm and 22x22, 48x13mm respectively.
The e-field shielded power composite inductors of the IHLP series provide a particularly innovative solution for EMC critical applications, which are especially prevalent in the automotive industry. Thanks to additional shielding, this easy-to-install and cost-effective solution reduces the negative impacts of the electric field significantly, generally by -20dB to 1cm.
In addition, power composite inductors are available with further new developments, for example the dual inductors of Vishay's IHLD inductor series. They are ideal for sophisticated Class-D audio amplifiers in the commercial and automotive sector. Thanks to the technical benefits of power composite technology, this type of inductor enables high-quality digital
audio systems with less distortion and the smallest possible footprint.
The coupled inductors of the IHCL inductor series have been designed, among other things, for SEPIC-DC/DC converters. Two inductors with a magnetic coupling of >90% are integrated in one compact package. They are temperature resistant to +155°C and available with inductance values of up to 47µH.
Even though composite technology offers many advantages, the use of ferrite inductors – generally with MnZn and NiZn cores – is still definitely justified, particularly for high frequencies and low eddy current losses.
They are also being further developed for use in high power applications. Sumida, for example, has developed the low-profile, high-current inductor series CDEP15D90 / T150 for use in automotive LED headlights. Recently, headlights have been diversified and some of them are now equipped with ADB (Adaptive Driving Beam) or AFS (Adaptive Front-lighting System). These systems require higher currents of up to approx. 15A.
Complying with the automotive reliability criteria AEC-Q200, these inductors are so strongly structured that their core and wire can withstand a voltage of up to 120V/DC. Measuring 16x16x10mm in size, they are specified for operating temperatures up to +150°C.
If sufficient space is available, radial lead mushroom core inductors, e.g. from Murata PS, Sumida, and Panasonic, offer a reasonably priced alternative. They are available as unshielded and magnetically shielded versions and come in various sizes.
Inductors are available at https://www.rutronik24.com/pg/inductors/ind/.