Monday, August 24, 2009

Transformer Design

Switch Mode Power Supplies (SMPS)
The popularity of integrated Off-Line Switching Controllers has opened the world of power supply design to engineers with little or no previous power supply design experience. Power is often the last thing considered in a circuit design and is often assigned to the engineer with the lowest project load at the moment. To quickly and efficiently accomplish the project, the use of an application note published by the leading vendors of integrated IC’s is often the easiest way to start. But to complete the design, the more difficult aspects in power, such as transformer design, EMI and layout must be addressed and is often where design engineers run into trouble.

ICE Components can help with the transformer through several support options.

Custom Switch Mode Power Supply (SMPS) Transformers.
Many times engineers cannot find standard transformers to meet their design needs and if so, may also lack the design experience to make a good transformer (hey, engineers actually can’t do it all!). ICE Components offers custom solutions through our SMPS Custom Design Process. Here engineers can create a basic design to quickly get their power supply up and operating. No magnetics experience is necessary as the design format is laid out in a simple step by step format. The sample request takes 5-10 minutes and samples are ready in about 5-10 business days. This really helps to facilitate a faster test cycle for designers.

Rapid Transformer Sample Service

If you work with Power Intergration (PI) chipsets you’ll be glad to know that ICE is a preferred vendor and provides a rapid transformer sample service (RTSS) link within PI’s website. You can request samples either through PI or through our website by submitting the PI Expert Design Tool output. A short 2 minutes is all that is needed to request samples that are made to your exact specifications. You can expect a response to your order within one business day and only 5-10 days are needed to get you up and going with your power supply.

IPT Series
ICE Components IPT series of switch mode power supply (SMPS) transformers have been designed to work with off-line Pulse Width Modulation (PWM) controllers with various IC companies; Fairchild Semiconductor, Infineon, ON Semiconductor, Power Integrations and ST Microlectronics to name a few. By going to our website and matching the IC chipset to the ICE transformer part number, you have the part you need to get your power supply board working quickly. ICE lists the corresponding APP note, power and input/output voltage levels, as well as part numbers, so making the proper selection is quick and easy.

TO Series SMPS Transformers
The TO Series of transformers were designed to match the specifications of the ON Semiconductor's NCP1207 PWM current-mode controller with quasi-resonant (QR) switching capability. ICE worked closely with ON Semi to develop this line of transformers. With power ranges from 25-85 watts and input voltages from 5-12V, just about every common application is covered. ICE also can make any custom requirement an engineer may need. Visit our TO Series for a complete line of standard transformers available to fit your ON Semi NCP1207 needs.

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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.
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Monday, August 17, 2009

Gate Drive Transformers and Isolation Transformers

Power MOSFETs often require a gate drive circuit to translate the on/off signals from an analog or digital controller into the power signals necessary to control the MOSFET. If the transformer is designed with low leakage inductance the propagation delays through the transformer can be less than 50 ns. The transformers from ICE Components offer a leakage inductance of a few hundred nanoHenries. This low value is obtained by using tightly coupled windings on a small ferrite core. Gate drive transformers from ICE Components have been tested and compared and shown to have some of the lowest leakage values seen in the industry.

The GT series is also often used as an isolation transformer. Sometimes a timing signal must be provided between primary to secondary. All transformers provide dc isolation between isolated windings. However, because they all have capacitance from a winding to any nearby conductor, such as other windings, the core, and the chassis, they can couple high frequency signals and noise to these nearby conductors. This capacitive coupling mechanism can carry high frequency noise on the input primary to the output secondary windings or vice versa. Isolation transformers from ICE Components offer very low interwinding capacitance values to minimize high frequency noise coupling. Isolation transformers from ICE Components have been tested and compared and shown to have some of the interwinding capacitance values seen in the industry.

GT01 Series
The GT01 series offers the smallest size available on the market and is designed for frequencies from 500 kHz to over 1 MHz and multiple turns ratios are available. With E-T Product values over 10 volt-microseconds, the GT01 series can be an effective gate drive transformer or isolation transformer.

GT02 Series
The GT02 series offers a low profile option with a maximum height of 3 mm and a higher Hi-Pot isolation (1500 Vdc) than the GT01 series. Also effective as an isolation or gate drive transformer.

GT03 Series
The GT03 series is our most popular series with ET Product values up to 69 volt-microseconds and Hi-Pot values up to 3750 Vac. This series also comes in a potted version offering creepage / clearance over 10 mm to meet medical VDE. The small package (10.7 x 16 x 6.8) and power performance meet many gate drive and isolation transformer requirements.

GT04 Series
The GT04 series is used for higher power applications and offers ET Product values to 378 volt-microseconds and Hi-Pot values up to 4500 Vdc. The GT04 series also meets medical safety isolation requirements.

The ICE Components family of gate drive transformers offer a wide range of standard product, but we also make many custom products based on customer applications and specific needs. We can easily adjust turns ratios and insulations systems for different temperature ratings, isolation voltages, as well as creepage / clearance needs.
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