Power Products in 3 Images or Less 

ISSUE: September 2009 

Voltage Transformer Delivers 130 A Efficiently for Servers

From V•I Chip, a subsidiary of Vicor, the VIV0005TFJ voltage transformer module (VTM) offers improved performance for server applications (Fig 1). Rated to deliver 130 A dc and 195 A peak, the VIV0005TFJ operates with an upstream preregulator module (PRM) to drive low-voltage, high-current processor and memory arrays, while operating with greater than 90 percent efficiency. The VIV0005TFJ achieves a current density of 117 A/in2 in the “full-size” (32.5- x 22.0- x 6.7-mm) V•I Chip package.

With its use of the company’s sine amplitude converter (SAC) technology, the VIV0005TFJ’s achieves an impedance of less than 1 milliohm from dc to 1 MHz, beyond the bandwidth of other solutions (Fig 2). That performance which means that capacitance normally placed at the load can be located at the input to the power converter. With a K factor of 1/40, this module can reduce the bulk capacitance value used for transient response—by a factor of 1600, resulting in savings of board area, materials, and total system cost.

In a conventional dc-dc converter design, 1600 µF of capacitance might be deployed at the load using an array of polymer aluminum capacitors. Contrast that with a VIV0005TFJ-based design, which would only requires a 1-µF ceramic capacitor at its input. That 1-µF capacitor is available in a 1206 case.

In addition to the VIV0005TFJ, A VTM with a K factor of 1/32 and 115-A dc output (part number VIV0007TFJ) is also available.

Fig 1. "This new high current VTM delivers 30 percent more current than previous versions, making a V•I Chip solution up to three times smaller than conventional solutions," says Stephen Oliver, VP of marketing and sales, "and that’s from a high efficiency 48-V distribution rail, not lossy 12-V systems. The output range enables the VIV0005TFJ to deliver high current at the lowest voltages on any processor roadmap, including the lowest voltage required by Intel’s VR12 server specification."

Fig 2. Output impedance versus frequency for VTM with a K factor of 1/32. (This data was previously published in &High Current, Low Voltage Solution for Microprocessor for Microprocessor Applications from 48V Input" by Paul A. Yeaman, Vicor V*I Chip, U.S.A, available online at

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