Shielded Power Inductors Tamp Down Noise in Dense DC-DC Converters

Bourns recently introduced its latest series of small, shielded power inductors. They’re designed to keep the noise down in dense DC-DC converter designs for consumer electronics and compact industrial power circuits.

The SRP2008DP series aims to address the growing demand for power density across the board in electronics. In these increasingly crowded layouts, electromagnetic interference (EMI) and other forms of noise are top concerns since interference between tightly packed power components can undermine system reliability.

The radiated emissions prevalent in these power circuits can also complicate electromagnetic compatibility (EMC) compliance. Shielded magnetics help manage these risks, but they traditionally occupy more PCB real estate than unshielded parts, said Bourns.

Craig Wedley, engineering director for magnetic products at Bourns, explained that these issues can be addressed by a new class of compact shielded inductors. Constructed with a metal-alloy powder core and placed into a low-profile package measuring 2.0 × 1.6 × 0.8 mm, Bourns said the SRP2008DP delivers saturation current capacity required by power-dense DC-DC converter designs without the design penalties that tend to come with it.

According to the company, the series covers inductance values of 0.24 to 4.70 μH while delivering saturation current (I_SAT) of 1.6 to 5.5 A and heating currents (I_RMS) of 1.1 to 3.5 A. The high saturation current is supported without core collapse under the load, and it can be maintained across the full operating temperature range, which spans from −40 to 125°C. The small footprint is designed to be dropped into compact power-conversion circuits with minimal changes to the circuit board.

Inside the Inductors: Metal-Alloy Powder Core Covered in Shielding

The mini-inductors are made from a metal-alloy powder core. It offers high resistivity that suppresses eddy currents and reduces core losses at high switching frequencies, preserving signal integrity in noise-sensitive designs, said Bourns.

The shielded construction of the SRP2008DP contains magnetic flux, reducing radiated emissions that can interfere with adjacent components on the PCB. The contained flux minimizes magnetic coupling to nearby traces and components, reducing the risk of interference in densely populated layouts. On top of that, the 0.8-mm low-profile package fits height-constrained designs where vertical space is limited for traditional, bulky shielded inductors.

“As electronic systems grow more sophisticated while shrinking in size, the components inside them have to keep pace,” said Wedley, adding that the new series “gives engineers all the safety, signal integrity, and compliance benefits of a shielded, high-current inductor in a footprint that doesn’t compromise their layout.”