Modular board-mounted DC/DC converters must be ever-smaller and easier to place and solder. To achieve this, RECOM utilizes the ‘Z’ dimension in 3D Power Packaging (3DPP), stacking a PCB or leadframe and components for maximum power density while maintaining minimum footprint and profile.


At higher powers, the RECOM RPMB/RPMH series are an example of a 30W part in a thermally-enhanced 25-pad LGA package 11.7mm x 12.19mm x 3.75mm high. This power density is achieved with a multilayer internal PCB which utilizes plugged and blind vias for good thermal conductivity and efficient use of the available space.

Construction is a four-layer PCB enclosed by six-sided metallic shielding for low EMI. This type of construction is low profile, but needs a little over 1.4 cm² of real estate to allow proper heat dissipation in order to deliver full power at ambient temperatures exceeding +85°C.


Non-isolated DC/DC switching regulator use has proliferated in ‘buck’ or ‘step-down’ formats, initially often replacing the traditional ‘three-terminal’ linear regulators, but now used widely as higher input voltage Point-of-Load regulators, providing a set of precise low-voltage rails for highly integrated ICs such as CPUs GPUs and SoC devices. Again, to confer a benefit over discrete solutions, a DC/DC switching regulator should occupy the absolute minimum footprint and height and run cool while meeting the exacting regulation and noise requirements of modern ICs. To achieve this small size implies high efficiency, which traditionally has meant low switching frequency and a consequently large output inductor – exactly the opposite of what’s needed. However, improved semiconductors, converter topologies and magnetic materials have allowed frequencies to push into the MHz range while maintaining excellent efficiency with a small integrated inductor

For example, the RECOM RPX series has a footprint of just 4.5mm x 4mm and 2mm high in a QFN package, yet provides up to 2.5A of output current at a peak efficiency of over 90%. The 1A version is even smaller, just 3mm x 5mm x 1.6mm high. This power density is achieved with a low-cost flip-chip on leadframe and integrated-inductor construction with over-molding, with the added benefits that the tight switching current loops generate very low EMI, along with high power density and optimized thermal performance, in a QFN package, that cannot be matched by a discrete solution.


The RS12-Z series of DC/DC converters achieves class-leading power density in a SIP8 format by leveraging off planar transformer technology with advanced packaging and thermal design. In a metal case, the series features high efficiency and operates at full 12W load to 75°C with convection cooling only (24V input). Pinout is industry standard with backwards-compatibility to 3W and 6W parts in the SIP8 format, for an easy power upgrade. Minimal external filtering is required to achieve EN 55032 EMC compliance, class A or B. The parts also include an output trim function and input under voltage lockout as well as continuous short circuit protection.


These DC/DC converters feature a 3D packaging technique that is unique to RECOM. A custom plastic moulding supports the control PCB which forms the top surface of the part, while the isolation transformer mounts underneath to achieve a minimum footprint overall, with a height between 5.8 and 8.5mm depending on family. The open-frame construction has particular value when surface-mount reflow profiles are too severe for potted or moulded parts. The R1SX series provides a single output at 1W up to 100°C while the R1DX provides dual outputs. Both parts are agency-certified with 3kV/1 second isolation. The R1ZX series is similar to the R1SX but includes a linear regulator for a precise, low noise output with 2kV/1 second isolation. The R2SX series provides 2W up to 75°C (100°C with derating) and withstands 3kV/1 second.


When safety agency-rated isolation is required, necessary creepage and clearance distances define a minimum X or Y dimension. For example, in medical applications with mains system voltages, 8mm creepage is required between input and output for two Measures of Patient Protection (2MOPP). Given this minimum packaging dimension, a more traditional approach can be taken, with an internal die for a power and control IC wire-bonded to a DVE SOIC-16 leadframe, then conventionally over-molded, such as in the RECOM R05CT05S part. The transformer in this DC/DC converter is a proprietary, very low profile, planar-type design, achieving 5k VAC isolation voltage and reinforced, 2MOPP isolation. The overall height of the part is only 2.65mm, making it suitable for card-type applications as the height of the isolated DC/DC converter is not higher as all of the other SMT component

Contact Info:

RECOM Power GmbH
Münzfeld 35
4810 Gmunden

Tel: +43 (0)7612-88325-700
Fax: +43 (0)7612-88325-801