Author:
Ally Winning, European Editor, PSD
Date
05/15/2025
PDF
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Philip Simpson, Field Applications Engineer at Vicor Corporation
There is currently a lot of traction in the automotive industry around the move from the 12V power distribution bus to the new 48V bus. The higher voltage offers a few advantages, but the main one is that increasing the voltage by a factor of four means that the current can be decreased by a similar proportion. This lower current allows thinner and lighter wiring and PCB traces to be used, decreasing the weight and size of the end solution. The automotive industry is not alone in the need for new ways to move lots of energy around the system. Currently, other industries also face similar challenges, particularly in data centres, but also in automated test, edge computing, and 5G networks.
Philip Simpson, Senior Field Applications Engineer at Vicor Corporation adds, “12V has traditionally been used in data centres, but server power levels have been progressively increasing. Some GPU chips and high performance compute processes have gotten customers asking us to deliver 1000A at 1V. Even at 100% efficiency, 1000 amps at 1V is 100A at 10V, and you've got to push that around the PCB with all the corresponding losses. There's a good argument for pushing up the bus to 48V to bring a more manageable working current of just over 20A. 48V has been used as the bus standard in communications applications for a while, so it is not completely new technology”.
Vicor has recently launched several new bidirectional, non-isolated and regulated modules to help designers deliver high efficiency 48V bus designs for industrial applications. The DCM3717 family of DC-DC converters is able to handle 750W or 1KW of power in a 36.7 x 17.3 x 5.2mm package, and the DCM3735 DC-DC converter can handle up to 2KW of power in a 36.7 x 35.4 x 5.2mm package. The devices have some of the highest power densities in the industry, at up to 5kW/in3, and a peak efficiency of over 96%. The DCM modules convert from 48V to 12V to power legacy devices, or for further down conversion to power lower voltage devices. The DCM modules are designed to be used with Vicor’s BCM high-voltage, fixed-ratio converter family that converts from high voltage (800V and 400V) to 48V. Four DCM modules can be paralleled together to provide a solution for higher power applications of up to 8KW.
Simpson expanded on how Vicor achieved those high levels of efficiency and density by saying, “We don't need GaN or SiC technology, only conventional silicon FETs. The new devices use a fully resonant Sine Amplitude Converter topology (SAC). Normally, PWM controllers need to be switched as fast as possible, as the longer they stay in linear mode, the higher their losses. That hard and fast switching causes problems with parasitics, and if the parasitics get too high, they can damage the FET. To prevent that, snubbers have to be used, or the switching speed slowed, incurring further losses. Our DCM modules use parasitics as part of the resonant circuit. All of the switching happens at zero current and zero voltage, so there is no need to hard drive the FET. The modules also provide very low noise operation. The fast edge in most PWM converters is where a lot of the radiated and conductive noise is generated. Our devices typically produce a little noise at the switching frequency, and then virtually nothing else. We typically say that these devices are 10 to 20dB quieter than an equivalent converter”.
The DCM modules are packaged in a 5.2mm high, low-profile SM-ChiP surface-mount package to reduce size and weight. The ChiP modules are plated (three-dimensionally interconnected or 3DI) with a thin layer of copper and then gold surface finished that is electrically and thermally conductive. The plating creates a Faraday shield, reducing EMI/RFI, and provides an ideal thermal interface.
