Tuesday, August 18, 2009

High Current Inductors

The advent of more powerful processors and lower core voltages has driven the need for higher and higher currents and high slew rates (period from no load to full load) from power supplies. Traditional power supply designs could provide the current but the high impedance on the output of typical DC/DC converters limited the slew rate or the rate of change of the current. To solve this problem the synchronous buck converter topology was developed and perfected initially for workstation and server applications or Voltage Regulator Modules (VRM). This topology features a fast switching frequency, low output impedance and slew rates to support the most demanding processor needs. As time moved on and high current processors moved to more main stream applications the need for inexpensive buck and synchronous buck solutions became widespread. To meet the needs of these applications a new type of inductor was created. These high current inductors feature a low inductance (typically 2.0 uH and below) and a high current rating (15A up to 100A) that are needed in these applications.

LP02 Series
The LP02 series of VRM inductors by ICE Components are a line of similarly constructed high current inductors that come in 5 different footprints. They are made with ferrite for lower losses at higher switching frequencies and a single turn of copper foil to achieve a lower DCR. Typical applications are Voltage Regulator Modules and Voltage Regulator Downs used in servers, blade servers and workstations where size and efficiency are key.

LP03 Series
The LPO3 series of inductors utilizes a helical coil and high flux material to achieve a very high saturation current for the roughly 14mm square footprint. It features one of the highest current densities of any inductor on the market. It’s use of hi-flux material makes it great for high current DC output filter applications although it can be used in buck applications when space is at a premium.

LP05 and LP06 Series
The LP05 and LP06 have a similar construction as the LP03 but use ferrite instead of the hi-flux to lower the switching losses and lower the cost. The LP06 is slightly larger than the LP05 for higher current applications. The use of ferrite reduces core loss at high frequency while the flat wire used in a helical coil reduces skin effect making it suitable for low cost high frequency applications. Buck/Boost, VRM, VRD and output filter applications are all popular for these ferrite based high current inductors.

LP07 Series
The LP07 uses a powdered iron core to lower the cost in this SMT package that is becoming popular among many magnetic vendors. The LP07 series features inductances ranging from 180nH to 3.90uH with a DCR as low as 0.32mOhms and a saturation current as high as 85A. These are excellent for use in buck converters and output filter inductors but will have the inherent weaknesses and strengths of powdered iron depending on the application.

LP08 Series
The LP08 was originally developed as a small footprint, low DCR and low cost solution for use in a high volume VRM applications. The part was so popular we decided to make it into a product series. It’s small footprint of only 11mm x 8mm with a saturation current of 45A in a ferrite core is really tough to beat. Other parts made with more lossy materials are available but the cost will be higher and the efficiency will be lower.

Non-Standard High Current Inductor Series
ICE quickly realized that every little bit made a difference with high current inductors. Customers constantly needed to reduce the footprint just a little or to a lower the DCR or a slight decrease in the height. AND ALWAYS MORE CURRENT. Before we knew it we had over 50 different designs in production that might meet the needs of other customers. Thus the name “Non-Standard” fits. These parts are not part of a standard product series, although are fully developed and ready for production. These Non-Standard high current inductors have a wide range of attributes as they use different core materials, winding configurations, etc…. Applications cover the entire spectrum from VRM and VRD to simple buck converters to output filter chokes for DC/DC converters.

Overall ICE has one of the strongest product offerings available for high current inductors. We have had a good bit of success in the computer workstation and server market driving the development of a broad range of inductors. If you are just starting a design that will handle a lot of current, ICE is a good place to start looking for an inductor. If we don’t have exactly what you need odds are we have something close that can get you up and running.