Posted on 01 February 2019

Opening The Gates To Efficiency

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 A few extra components and the units comply with EMC regulations

In today’s world of increasing fuel costs, the need for ever more efficient operation is a powerful motivator. Introduction of the latest innovative developments available to satisfy this demand.

By Carey Windeatt , TDK/Lambda


Efficiency is fast becoming the ‘holy grail’ of the power industry, for a number of significant reasons. Let’s take a look at the demands imposed on industry to gain a better understanding of the drivers for improved efficiency.

Every design engineer accepts that better efficiency equates to less heat being generated, in other words system power density is optimised through the trade-off between power loss and magnetic component size. This can represent a cost saving to the user as less ‘real estate’ is required for the DCDC converter. Less heat generated means lower temperature rise which in turn reduces thermal stress on components and leads to increased reliability.

Being more efficient consumes less power, which leads to lower cost of ownership to the equipment end user. And perhaps most importantly, there is a global trend towards legislation for minimum operating efficiencies for equipment. Already the industry sees Energy Star and 80+ taking hold in the US for the PC and server industries. EU codes of conduct are in place, and harmonisation discussions with the US are taking place. It’s only a matter of time before this type of legislation, demanding set efficiency targets, becomes mandatory across a wide range of user applications throughout Europe. It has been estimated that saving 1W of power consumption at board level saves 2W in the power supply chain. In today’s world of increasing fuel costs/power costs, drive to reduce harmful emissions and corporate ‘green’ responsibilities, the need for ever more efficient operation is a powerful motivator.

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But, before we go into the topic of efficiency, let’s take a side step to look at another important development within the power supply industry. Although there’s a raft of standards within the industry that define key performance specifications, such as EMC, or safety approvals, such as medical (IEC/EN60601-1) and telecoms (IEC/EN60950-1), it’s only been in the last few years that manufacturers within the industry have joined forces to create and develop standards in footprint and pinout. However, nothing’s ever easy and the power industry is split into two camps.

The first camp is POLA (Point Of Load Alliance), which was set up by Artesyn, Texas Instruments and Astec Power in June 2003, agreed to develop point-of-load (POL) converters that have the same functionality, pin-outs and form factors, ensuring true product interoperability. The ultimate aim is to address the principal component sourcing concerns of electronics OEMs – competitive pricing and long-term security of supply – by standardising POL converters. In other words, it’s a single design from multiple manufacturers.

This is a great initiative except that if there is an inherent problem with a particular POL converter, no matter which manufacturer built it all POL converters will have that problem. Recent industry changes call into question the long term existence of POLA in its current structure.

Sitting in the DOSA (Distributed-power Open Standards Alliance) camp are manufacturers such as SynQor, Tyco Electronics and TDK/Lambda. DOSA defines the footprint and pinout for a given product platform whilst allowing a free hand in the electrical design. This gives power engineers a true and independent alternative source option.

Being an active member of DOSA puts TDK/Lambda in the driving seat to participate and contribute to the definition of the standard platform definitions for DC-DC converters. It is more to help TDK/Lambda customers by facilitating a true alternative sourcing strategy, as an option to other sourcing choices including single designs manufactured under license, delivering different user benefits.

Delivering very high operating efficiencies over a wide range of load conditions, TDK/ Lambda’s new iQE series of quarter-brick DC-DC converters responds to the ever increasing demand for improved efficiency under all normal operating load conditions. The iQE series is rated at up to 204W, and offered with two input voltage ranges – either 18V to 36V or 36V to 75V. A key highlight is the very high efficiency rating reaching up to 94%. What’s more, the efficiency curve remains high and incredibly flat, staying at more than 91% efficiency, under a wide 25% to 100% load.

With a broad range of output voltages from 3.3 to 15V and providing high power ratings, these DC-DC converters are ideal for engineers seeking excellent efficiency and optimal thermal performance for 24V and 48V power architectures in many applications within the industrial, telecommunications, data communications, access and wireless markets.

As designers are challenged to consider equipment redundancy or hugely varying load demands, the majority of final products work at between 25 to 60% of load. Unfortunately, power manufacturers have a tendency to fine tune DC-DC converters for maximum efficiency at a specific load point – this efficiency rating is usually the one highlighted in product data sheets. Under these circumstances where the final design is not working at this optimal point, the converter can be working inefficiently consuming more power than necessary and generating unwanted heat. The flat efficiency curve on the iQE series ensures that the final design doesn’t suffer when loadings don’t hit the ‘sweet spot’.

Throughout the open frame, single board construction, particular attention has been made to the overall thermal design including component height, location and orientation. As a result, the iQE family is compatible with all cooling strategies, including contact, convection and forced air, and offers outstanding thermal performance for cooler operation over its operating temperature range of -40ºC to +125ºC.

The wide operating range allows the product to be used in a very broad range of applications, including harsh outdoor environments where in deep winter conditions extreme cold might well be experienced. And, on the other hand, in high summer the combined effects of equipment self-heating and solar radiation could cause equipment internal temperatures to become very high. Even customer equipment not subjected to these wide temperature extremes benefits from the high quality and reliability designed into the product built to withstand such extremes.

So these products are well-suited for designin opportunities requiring high quality and reliability in remote outdoor applications like base stations and mast head equipment, all the way through to benign indoor applications like test & measurement or medical diagnostic equipment.

Following on from the successful iQB range of quarter-brick converters, the low component count on the iQE series together with the planar magnetics provide reliability and a more cost-effective total cost of ownership solution than many modules on the market. The iQE series features industry standard DOSA compatible pinout and quarter brick footprint, fixed frequency operation at 300kHz and low noise output for powering a broad range of applications including RF, DPA, POLs, FPGA, ASIC, DSP, microprocessors, access, optical and industrial loads.

Further, the input is fully isolated from the output adding to the iQE’s versatility by allowing different output polarity and grounding connectivity. Standard features include remote sense, remote on/off, and auto recovery of input under voltage, output over voltage, output over current and over temperature protection circuitry. Positive polarity on/off is offered as an option. iQE DC-DC converters are approved to a wide range of national and international standards, including UL, CSA, VDE and CE, making it simple for users to obtain regulatory approval for equipment which incorporates them. With the addition of a few extra components, the units will also comply with EMC regulations to EN55022 Class A/B. All equipment is required to conform to some EMC emission standard. There are typically two levels, ‘A’ the least onerous, and ‘B’ more so. As every application is different, so the actual EMI filter required will vary from one to the next. However, in order to provide the design engineer with a starting point TDK/Lambda provides a reference filter design, which comprises of a few capacitors and inductors. In the iQE series, for instance, five components would be required to achieve level ‘A’ and between five and six for ‘B’.

Brief design notes are contained in the product data sheet, supporting the iQE series. However, recognising that every application is different and it not being possible to provide one recipe for all, TDK/Lambda provides a high level of technical support, with experienced applications engineers on hand to provide help and advice if required. The iQE series is designed by power module specialists TDK Innoveta Inc and marketed in Europe by TDK Electronics Europe and Lambda Europe.


For further information about TDK/Lambda and the iQE series, visit:



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