1400W 12V High-Efficiency Phase-Shift Full-Bridge Evaluation Board

November 17, 2019 by Paul Shepard

The EVAL_1K4W_ZVS_FB_SMD dc-dc converter evaluation board proves the feasibility of using a phase-shift full-bridge (PSFB) topology as high efficiency topology at the level of fully resonant topologies when combined with the latest Infineon technology devices.

It proves that digital control, powered by XMC™ Infineon microcontrollers, is not only capable of controlling PSFB topology but also to overcome its drawbacks and enable the usage of the latest Infineon devices to achieve the best possible performance.

This converter provides a complete Infineon system solution for a 1400W dc-dc converter 400V to 12V which achieves 97% peak efficiency. The achieved power density is in the range of 3.7W/cm³ (60.78W/in³), which is enabled by the use of SMD packages, the innovative stacked magnetic construction and the innovative cooling solution.

Summary of features

  • Full SMD solution
  • Innovative cooling concept
  • Novel integrated magnetics structure
  • High efficiency, high power density

Summary of benefits

  • Full or nearly full ZVS in all load range
  • Full digital control
  • SR drain overshoot reduction (patent pending)
  • Best performance HV and LV power devices

The CoolMOS™ CFD7 in ThinPAK package, is the most recent and best performance high voltage fast body diode device from Infineon, combined with a low parasitic package and an optimized layout achieves incomparable performance with minimum stress on devices, enabled also by the innovative cooling concept presented in this board.

Background and system description

The trend in SMPS in recent years has been toward increased power density with optimized cost. In achieving this higher power density, high efficiency is a key parameter, because heat dissipation must be minimized.

Toward this goal, fully resonant topologies such as LLC are often considered to be the best approach in this power range and voltage class. However, the 1400W PSFB with SMDs is an example of how the improvement in semiconductor technology and control algorithms allows a simple and well-known topology block like PSFB to reach the high efficiency levels traditionally considered out of reach for this topology.

Measured efficiency of 1400W SMD PSFB at 400V input and 12V output. (click on graph to enlarge)

The efficiency shown above can be achieved by using a 600V CoolMOS™ CFD7 in SMD package together with 60V OptiMOS™ 5 SRs. The outstanding performance of these semiconductor technologies, the innovative cooling concept for a full SMD solution and the stacked magnetic construction enables a power density in the range of 3.70W/cm³ (60.78W/in³). Due to production tolerances, efficiency variations in the range of 0.1 percent could be expected in the results shown here.

The 1400W PSFB SMD is a dc-dc converter developed with Infineon power semiconductors as well as Infineon drivers and controllers. The Infineon devices used in the implementation of the 1400W PSFB SMD are:

  • 140mΩ 600V CoolMOS™ CFD7 (IPL60R140CFD7) in the HV bridge
  • 6 60V OptiMOS™ 5 in Super SO-8 package (BSC016N60NS5) in the LV bridge
  • 2EDS8265H safety isolated and 1EDN7512G non-isolated gate drivers (EiceDRIVER™)
  • ICE5QSAG QR flyback controller with external 4.5Ω 950V CoolMOS™ P7 (IPU80R4K5P7) for the auxiliary supply
  • XMC4200 microcontroller for control implementation (XMC4200-F64k256AB)
  • Medium-power Schottky diode BAT165
  • IFX91041EJV33 dc-dc step-down voltage regulator