Power Electronics

Spotlight on Magnetics

Shielded Inductors

From Cooper Bussmann, the SD38 Series of low-profile, shielded inductors feature 3.8 mm × 3.8 mm shielded drum cores available in 1.2-mm and 1.4-mm profiles. These devices offer inductances ranging from 0.47 µH to 680 µH with current ratings ranging from 0.100 A to 4.44 A. The operating temperature range is -40°C to 85°C. Pricing for the SD38 inductors is $0.35 to $0.39.

Isolation Transformer

Signal Transformer, a subsidiary of Bel Fuse, announced the expansion of its M4L Series of International Power Isolation Transformers to include the 450-VA rated M4L-1-4, M4L-2-4 and M4L-3-4. These transformers provide reinforced isolation between mains supply and sensitive electronic equipment. They are ideally employed in a broad range of medical and dental instruments.

The chassis-mount devices feature a nonconcentric winding platform to provide reinforced isolation and superior dielectric performance. Furthermore, the high-efficiency, laminated transformers boast a vertical- mount configuration to minimize their footprint, and a modular “touch safe” terminal assembly to prevent shock hazards. The new parts are in full compliance with the leakage and insulation requirements as stipulated by the IEC 61558-1-2 and UL 60601-1. In 100-unit quantities, pricing on the M4L series ranges from $59.50 to $62.45 each, depending on operational voltage.

Magnetics Design Tool

Version 6.0 of PI Expert Suite, Power Integrations' design software for switched-mode power supplies based on the company's ICs, includes PI Transformer Designer, a tool that produces detailed transformer specifications for power supply designs. The magnetics design tool shortens one of the most time-consuming steps in power supply design, cutting hours or even days out of the design cycle.

PI Transformer Designer generates step-by-step winding instructions and detailed material requirements, greatly simplifying the task of building prototypes or requesting samples from transformer vendors. The tool supports multi-filar windings, foil windings, and ac-stacked transformers. It also provides guidance on the use of low-cost shield windings to reduce EMI. PI Expert is available on CD ROM and may be downloaded directly from the company's website.

High-current Power Inductors Stay Cool

J.W. Miller has introduced the new Low-Loss Series 2100LL, 2200LL and 2300LL of high-current toroid power inductors. The key to the new low core loss inductor is the material of construction. The LL Series design incorporates a MAGNETICS Kool Mµ or equivalent toroid core. These distributed air gap cores are made from ferrous alloy powder. This enables the component to maintain a low temperature rise, making it suitable for low losses at elevated frequencies.

The new series is available in both horizontal- and vertical-mounting configurations for complete installation versatility. Typical applications include switched-mode power supplies, dc-dc converters, output chokes, power factor correction, EMI filters and energy storage.

Pricing is from $2 to $2.75 each, depending on the value and production quantity.

40-A SMT Inductors

Vishay Intertechnology's IHLP-2525AH-01 series inductors deliver saturation currents ranging from 8 A to 40 A in a 2525 package that measures 6.47 mm × 6.86 mm × 1.8 mm. Typical DCR values range from 3 mΩ to 76.6 mΩ over a standard inductance range of 0.1 µH to 4.7 µH, with a tolerance of ±20%. At full-rated current, IHLP inductors feature an inductance drop of less than 20%.

The inductors handle high transient current spikes without saturation and operate over a frequency range up to 5 MHz and at temperatures ranging from -55°C to 125°C. Pricing in 10,000-piece quantities starts at $0.82.

1-A Chip Inductor in 1210 Case Size

Taiyo Yuden (USA) announces a wire-wound chip inductor with a 1-A current rating in a standard 1210 case size: the CBC3225-4R7MR.

Designed specifically for space-critical dc-dc converter choke-coil applications in battery-powered portables, the 4.7-µH rated CBC3225- 4R7MR's ultra-compact 8 mm2 (3.2 mm × 2.5 mm) footprint provides an almost 70% surface-area reduction compared to comparably rated power inductors that typically require up to 25 mm2 (5 mm × 5 mm) of PCB real estate.

The models in the CBC3225 series offer engineers design flexibility with current and inductance ratings from 270 µA to 1440 µA and 1 µH to 100 µH, respectively. The sample price for the CBC3225-4R7MR is $0.15 each.

Planar Magnetic Transformers

From Aqavia Power, the PL58 Series planar magnetic transformers are optimized for use in forward converter with active clamp and ZVT full-bridge topologies. These transformers are typically rated at 100 W to 300 W in the forward topology and 200 W to 600 W in the ZVT full-bridge topology. Featuring a maximum height of 9.3 mm or 10.2 mm, these devices are designed for operation at 100 kHz to 1 MHz. A list of transformer options is shown in the table. Pricing for the PL5801-41 part is $4.50 in quantities of 10,000.
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Ferrite Material

TT electronics MMG's has designed new power ferrite material for handling high-saturation currents in small packages with low losses. Designated as F49 ferrite material, it exhibits a high saturation flux density with losses minimized between 60°C and 80°C.

Although this very high Bsat material has slightly higher losses than the company's commercial F48 or F47 grades, the improved saturation flux density in the F49 makes this material an ideal choice for many power management applications where potential saturating currents are a concern.

Ferroresonant Transformers

Ferroresonant transformers from Foster transformer provide a stable power output (typically 63%) for input voltages that vary as much as 615%. The standard square wave output requires less filtering than linear transformers for dc applications. Low component count provides exceptional reliability under extreme operating conditions.

Ferroresonant transformers are ideal for use in battery chargers, medical equipment, inverter and UPS systems, line-voltage stabilizers, and industrial automation and machine tools.

Boost Inductor without Litz Wire

Tabtronics introduced the first magnetic component based on its Hyper-X magnetic winding optimization technology. The Hyper-XMT HXLB40002 boost inductor — designed for boost converters with a 100-kHz switching frequency — delivers 800 W of output (400 V at 2 A) while operating from a 120 Vdc input. Dissipation using this inductor is less than 1% of output.

Using the company's winding technique on the inductor reduces ac losses by 70% versus conventional designs without using Litz wire. This approach eliminates the added expense of using Litz wire, which costs three times as much as solid wire. At the same time, the winding technique avoids the increase in dc losses associated with Litz wire. Hyper-X is a universal winding technology, and the company plans to apply it to various types of magnetic components.

Current-sensing Transformers

C&D Technologies' new series of current-sensing transformers are designed to measure and monitor ac currents. Combining an isolation voltage of 500 Vdc and a primary current rating of 10 A, the 5600 range is suitable for use in applications including switched-mode power supplies, motor current load monitoring, lighting and instrumentation.

Available in 50, 100, 200 and 300 turn variants, the transformers have an operating frequency range of 20 kHz to 200 kHz, an operating temperature range of -40°C to +85°C and measure 16.79 mm × 20.19 mm × 8.89 mm. Center-tapped versions of the 5600 series also are available, reducing component count in the full wave analysis configuration.

When used in switched-mode power supplies, the transformers act as feedback elements between the output and pulse control circuitry, providing accurate regulation. Parts from this series have inductance values from 5 mH to 335 mH, while dc resistance values range from 117 mΩ to 8.59 Ω.

Pricing for transformers is under $1 in OEM quantities.

Current-sense Transformers Meet RoHS

CT Series Current Sense Transformers manufactured by Datatronics Distribution now meet the requirements of European Directive 20002/95/EC (RoHS).

The CT Series Current Sense Transformers for dc-dc converter applications feature a compact 6-mm2 surface mount design with a 4-mm seated height. Turns ratios are available from 1:20 to 1:200, and it performs optimally at frequencies of 100 kHz and above. Key electrical parameters include an inductance range of 100 µH to 11,000 µH, a resistance range of 0.50 Ω to 27.50 Ω maximum and an isolation voltage of 500 VRMS minimum.

Datatronics will be compliant with the EU's RoHS directive for all of its standard product lines by June 2005. Upon customer request, Datatronics will supply RoHS-compliant components in the interim time period.

Integrated Dual Inductor

Pulse, a Technitrol Co., announces its integrated ferrite-bead inductor. The PA0766NLT Power Bead inductor contains two independent inductors integrated into a single core structure and part number with no magnetic coupling between the two inductors. Replacing two discrete inductors with one Power Bead inductor reduces the footprint and the PCB cost and improves circuit performance.

Pulse's PA0766NLT series can be used in any multiphase circuit application. Although typically used for double data rate (DDR) memory, multiphase CPU power and other desktop, portable and server computing applications, it also can be used in 2-phase and 4-phase telecommunications power systems.

Parts in this series are only available in tape and reel. Pricing for the integrated ferrite-bead inductor averages $0.46 per unit for a quantity of 100,000 units per order.

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