Direct-to-PoL power modules target Google-backed 48-V servers
The modules, which allow contemporary low-voltage, high-current CPUs, GPUs, ASICs and DDR memory to be powered off of a 48 V distribution bus, claim to enable unprecedented power density, conversion efficiency and low power system distribution loss. Evidencing advances in power conversion engines, control systems and modular power technology, Vicor’s latest 48 V modules are being introduced following the Open Compute Project (OCP) Summit 2016 at which Google announced its initiative to promote 48 V server and distribution infrastructure as a standard for data centers.
“By developing its 48 V server infrastructure, Google pioneered green data centers. And by promoting an open 48 V rack standard, Google is now enabling a reduction in the global cloud electricity footprint,” said Patrizio Vinciarelli, President and CEO of Vicor.
Efficient, dense, cost-effective and reliable power distribution is a critical element in data centers and other distributed electronics applications, such as autonomous driving vehicles and LED lighting. Although the benefits of a higher distribution bus voltage, particularly 48 V, which requires no special safety precautions, are well known (smaller cables and bus bars, lower distribution losses, smaller storage capacitors), conventional power conversion approaches have not been able to efficiently, or compactly, transform power from a 48 V bus into the low voltages (e.g., 3.3 V, 1.8 V and 0.8 V) and high currents (e.g. 95 Amps) required by contemporary CPUs or GPUs. As a result, CPU power conversion has customarily relied on 12 V distribution. A 12 V bus, however, must carry four times the current carried by a 48 V bus, and, because distribution losses are a function of the square of the current, the power lost in a 12 V bus can be as much as 16 times the loss in a 48 V bus. By providing efficiencies from a 48 V bus that are better than 12 V legacy solutions, in a fraction of the space, Vicor’s 48 V Direct-to-PoL product families enable system designers to implement green distributed system solutions featuring high conversion efficiency, high power density and low distribution loss.
Vicor’s latest generation 48 V Direct-to-PoL modules include the Cool-Power PI3751-02 Buck-Boost, Pre-Regulator Module (PRM) and the VTM48Kp020x Current Multiplier Module (VTM). The PRM receives its input from a 48 V distributed bus (Vin up to 55 V) and drives a controlled ‘factorized’ bus voltage to the VTM; the VTM generates an output voltage that is 1/24th of the voltage at its input while multiplying by 24x the current delivered to the CPU. Current multiplication by as much as 48x at the Point-of-Load delivers higher efficiency, density and bandwidth, distinguishing attributes of Factorized Power. In applications that require telemetry and digital control (e.g., CPU, GPU, ASIC and DDR4 memory applications) a Vicor PI3020 Digital Control and Telemetry device may be used with a VTM/PRM pair. Among the features of the PI3020 are PMBus and SVID control interfaces with full support for server processor power VR13, and backwards compatibility for VR12.5 and VR12.0 designs.
Utilizing a MHz ZVS Buck-Boost topology in a 10 mm x 14 mm LGA package, the PRM delivers up to 240 Watts at 98% efficiency. The VTM’s MHz ZVS/ZCS Sine Amplitude Converter (SAC) delivers up to 95 Amperes of continuous current, and up to 190 A of peak current, at 95% peak efficiency in a molded 13 mm x 23 mm ChiP package with greater than 400 A/in2 current density.
The VTM features low output impedance, allowing users to remove bulk capacitors from the Point-of-Load. Furthermore, only the high current VTM needs to be close to the CPU; the PRM can be located remotely. And, whereas conventional buck regulator solutions require enough phases to handle the full transient current demanded by a CPU operating in ‘turbo’ or ‘boost’ mode, the VTM’s own Turbo Mode delivers up to twice its rated continuous current for up to 10 ms, thereby accommodating transient CPU operating modes without sacrificing system power density and cost.
Vicor has pioneered 48 V direct-to-PoL power conversion. The latest generation products expand a family of VTM and PRM modules that have exhibited substantial improvements in each generation. Over the past decade, Vicor has, in fact, reduced converter power loss by an average of 25% every two years while increasing power density. Compared to solutions using traditional ‘multi-phase’ buck regulators, Factorized Power offers superior efficiency, density, transient response and noise performance. A third party study has recently demonstrated that the VTM’s noise spectrum is an order of magnitude lower than legacy multi-phase buck regulators.
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