industry news
Subscribe Now

ROHM’s Isolated DC-DC Converters for xEVs Reduce Application Size and Minimize Noise Design Countermeasures

Contributes to smaller mounting area in isolation circuit by 30% compared with standard products
Santa Clara, CA and Kyoto, Japan, Jan. 25, 2023 (GLOBE NEWSWIRE) — ROHM Semiconductor today introduced the BD7Fx05EFJ-C isolated flyback DC-DC converter (BD7F105EFJ-CBD7F205EFJ-C) optimized for gate drive power supplies in xEV applications, such as electric compressors and PTC heaters.

In recent years, xEVs such as hybrid and electric vehicles have become increasingly popular as the industry moves towards achieving a sustainable society. xEVs, which primarily use electricity as their energy source, are equipped with unique applications such as electric compressors for AC, and PTC heaters to raise the cabin temperature. As these applications are driven by high voltages, it is necessary to isolate the primary circuit that includes the battery from the secondary circuit comprised of the motor and other systems to ensure safety. However, in addition to issues such as larger mounting area and power consumption, conventional isolated circuit configurations require considerable noise countermeasures for switching frequencies that vary with output current.

ROHM’s new product utilizes a circuit configuration that achieves stable switching frequency characteristics without requiring a photocoupler, decreasing application size together with the workload needed for noise design countermeasures. Leveraging ROHM’s superior analog design technology allows the BD7Fx05EFJ-C to eliminate the need for photocouplers, transformer auxiliary windings, and peripheral components conventionally necessary to detect secondary-side voltage and current. Along with solving issues with photocouplers (e.g., large power consumption, fluctuating detection accuracy due to temperature, and deterioration over time), ROHM has also achieved greater miniaturization by reducing the number of components – including the photocoupler – used for current detection by 10 (equivalent to a board area of 30%) compared to general isolated flyback power supply circuits.

The BD7Fx05EFJ-C is also equipped with an adaptive ON-time control function that fixes the switching ON time, ensuring a stable frequency of around 350kHz regardless of output power. To be complaint with the CISPR25 automotive EMC standard requires considerable noise design in the frequency range from 150kHz to 300kHz, but as ROHM’s new converters do not fall within this band, noise countermeasures can be greatly simplified. This, together with a spread spectrum function that minimizes radiated noise, contributes to reducing the number of efforts for noise design.

Going forward, ROHM will continue to develop products that contribute to greater miniaturization and lower noise by leveraging its strength in analog technology, helping to achieve a sustainable society.

Product Lineup
In addition to reducing the number of components and person-hours required for noise countermeasures, the BD7Fx05EFJ-C improves application reliability by incorporating multiple protection circuits along with a function that stabilizes the output voltage. View the product specifications here.

Application Examples
ROHM’s new DC-DC converter IC is ideal for gate driver power supplies that must be isolated from the battery for safety.

  • Automotive: Electric compressors, PTC heaters, inverters
  • Industrial: Power supplies, PLC (Programable Logic Controller), inverters


  • Available now (in mass production)
  • Online distributors: Digi-KeyMouser, and Farnell
  • Scheduled for release at other online distributors

Product Ordering Information


Leave a Reply

featured blogs
Mar 23, 2023
Explore AI chip architecture and learn how AI's requirements and applications shape AI optimized hardware design across processors, memory chips, and more. The post Why AI Requires a New Chip Architecture appeared first on New Horizons for Chip Design....
Mar 22, 2023
There are few things that get me more excited (at work) than an awesome CFD solution. And as a frugal engineer, I'm all about being efficient. Here's a CFD simulation that doubles down on efficiency. NASA E3 In the early 1980s, NASA's Energy Efficient Engine (E...
Mar 10, 2023
A proven guide to enable project managers to successfully take over ongoing projects and get the work done!...

featured video

First CXL 2.0 IP Interoperability Demo with Compliance Tests

Sponsored by Synopsys

In this video, Sr. R&D Engineer Rehan Iqbal, will guide you through Synopsys CXL IP passing compliance tests and demonstrating our seamless interoperability with Teladyne LeCroy Z516 Exerciser. This first-of-its-kind interoperability demo is a testament to Synopsys' commitment to delivering reliable IP solutions.

Learn more about Synopsys CXL here

featured chalk talk

Traction Inverter
Sponsored by Infineon
Not only are traction inverters integral parts of an electric drive train and vital to the vehicle motion, but they can also make a big difference when it comes to the energy efficiency and functional safety of electric vehicles. In this episode of Chalk Talk, Amelia Dalton chats with Mathew Anil from Infineon about the variety of roles that traction inverters play battery electric vehicles, how silicon carbide technology in traction inverters can reduce the size of electric car batteries and how traction inverters can also help with cost reduction, functional safety and more.
Nov 9, 2022