New Tech Tuesdays: Hybrid Power Modules Simplify High-Power Bus Conversion

New Tech Tuesdays

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The 48V bus was once considered a high-voltage niche for telephony, tucked away in dedicated rooms. Today, the 48V voltage rail is the backbone of modern data centers, networking, and industrial power architecture, driving the need for increasingly compact and efficient converters to step down to lower, usable voltages. Engineers are constantly seeking a system-in-package (SiP) solution that can handle high power without compromising efficiency or generating excessive heat.

This week’s New Tech Tuesdays explores how hybrid DC-to-DC power modules can leverage advanced switched-capacitor topology to redefine non-isolated intermediate bus conversion.

The telecom and networking equipment industries present the greatest demand for high-efficiency, non-isolated conversion. These systems rely on the 48V intermediate bus for power distribution, requiring a high-density solution to efficiently step down to voltage rails between 4.5V and 18V. DC-to-DC power modules, such as those with a hybrid switched-capacitor topology, can drastically improve performance for these applications. This topology can expertly handle the wide voltage range while helping to maintain peak efficiencies, which is a critical metric in energy-conscious data centers.

Robust, high-current conversion is equally vital in industrial power architectures and test and measurement equipment. Many industrial power buses operate up to 55V, demanding a highly reliable converter that can source power as well as sink it in bidirectional applications, such as those involving regenerative loads. Furthermore, features like short-circuit protection with an adjustable retry-timer and overtemperature monitoring are essential for maintaining uptime and reliability in harsh factory and laboratory settings.

To manage the power challenges associated with robust 48V bus conversion, the LTM4654 hybrid step-down µModule^® bus converter from Analog Devices offers a solution with low electromagnetic interference (EMI), source and sink capability, and a wide input voltage range. The highly integrated converter, which requires only external flying and bulk capacitors, is scalable by paralleling multiple units to support much higher current demands. The device’s combination of high efficiency and thermal innovation makes it the definitive choice for next-generation power systems.

The µModule’s physical design is optimized for high power density within a compact ball grid array (BGA) package (Figure 1). One of the device’s key innovations is the deliberate exposure of the power inductor on the top surface, which creates an intrinsic and direct path for heat to escape up and out, thereby minimizing thermal stress on the PCB and enabling operation up to an internal temperature of 125°C. For applications requiring more than 300W, the module is easily scalable and can be parallel, ensuring excellent current sharing for much higher-power systems without sacrificing board space.

Figure 1: Module converter is housed in a compact BGA package that integrates a switching controller IC, power MOSFETs, and magnetics, significantly simplifying power system design and reducing board space. (Source: Mouser Electronics)

Whether in telecom, networking, test, or industrial applications, the µModule’s performance is made possible by a specialized power architecture. The LTM4654’s hybrid approach combines the soft-switching benefits of a switched-capacitor front-end with a traditional step-down regulator. This combination efficiently steps the high input voltage down to an intermediate half-voltage point before the final regulation stage. Additionally, these bus converters support a maximum 36A load current while integrating essential features like a proprietary capacitor balancing phase during startup, which minimizes inrush currents typical of purely capacitive switching circuits.

Hybrid-topology power modules, such as the LTM4654 µModule, are essential for modern power management, particularly in telecom, networking, test, and industrial systems. Its specialized architecture, which combines a switched-capacitor front-end with switching regulation, delivers excellent efficiency and thermal performance for 48V non-isolated intermediate bus conversion. The module provides a robust, scalable solution with bidirectional power flow and fault protection, making it ideal for achieving high power density in constrained and demanding applications.