Intermediate Bus Converters Deliver Up to 450 W

Jun 29, 2005 6:04 PM
By David Morrison, Editor, PETech

Artesyn Technologies has extended its Typhoon family of dc-dc converters with the introduction of three intermediate bus converters (IBCs) that deliver as much as 450 W of output in a quarter-brick package. These isolated dc-dc converters, which represent the second generation of the company’s IBCs, employ new conversion topology to deliver as much as 50% more power than the company’s previous-generation IBCs. The series includes the IBC38AQT unregulated, fixed-ratio dc transformer for computing, and two semi-regulated models with input voltage ranges optimized for telecom (IBC28AQW) and networking (IBC30AQS) applications.

The IBC38AQT, IBC28AQW and IBC30AQS are rated for output currents of 37.5 A, 28 A and 30 A, respectively, each at 12-V output. In addition, these IBCs achieve efficiencies as high as 95.5% in the case of the unregulated model and 94.5% for the semi-regulated models.

The IBC38AQT fixed-ratio dc transformer has an input range of 42 V to 53 V, and can generate up to 37.5 A at 12 V. This unregulated, open-loop chopper-type converter has a minimal line regulation specification of +10% to -12.5%, but maintains load regulation to within ±1.5% from zero to full load. It provides a cost-effective solution for applications with well-regulated 48-V supplies or for feeding general-purpose wide-input POL converters, which can tolerate some supply variation. Typically, fixed-ratio IBCs are used for cost-sensitive applications in the computer, storage and server markets.

The IBC28AQW features a wide industry-standard 36-V to 75-V input for telecom applications, while the IBC30AQS has a narrower 42-V to 53-V input suitable for datacom applications. Both models generate an isolated 12-V output with a setpoint accuracy of ±0.25%. Either model can be paralleled to achieve higher current ratings than that of the individual units. The IBC28AQW and IBC30AQS use closed-loop control techniques to maintain output regulation to within ±2% for all load currents from zero to maximum rated output, and have line regulation figures of ±1.0% and ±0.3%, respectively.

All three second-generation quarter-brick IBCs use a full-bridge conversion topology, with a primary-side microprocessor supervising the PWM controller to maximize performance. This topology also employs a “driven synchronous system,” in which all power switches are directly controlled by the PWM controller. Compared to the conventional self-driven synchronous rectifier approach, the driven synchronous system provides much tighter timing control of the secondary-side switches, resulting in higher efficiency and, in the case of the closed-loop, semi-regulated models, better output voltage regulation. All three IBCs also feature a novel distributed power train, using two power cores instead of one, which increases overall efficiency and improves thermal management and reliability by dispersing heat evenly across the entire module.

Based on an open-frame, single-board design, these IBCs are designed for through-hole board mounting. There is a choice of two body heights and three pin lengths to accommodate different board layouts and thickness. Designed for fully automated assembly, the modules are constructed entirely from surface-mount components, using planar, in-the-board transformer structures to minimize profile. The low-profile versions have an installed height of just 0.40 in.

All three models are designed for operation over an ambient temperature range of -40°C to +85°C without a heatsink, and are suitable for both convection-cooled and forced-air environments. They are fully protected against overtemperature and short-circuit conditions, and also feature non-latching overvoltage protection and input undervoltage lockout. Artesyn’s Typhoon quarter-brick IBCs are available for immediate delivery. In OEM quantities of 1000, unit prices are $62.70 for the 37.5-A fixed-ratio model, $65.90 for the 30-A narrow-input model and $73.25 for the wide-input 28-A model.

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