ROHM’s New 4th Gen Fast Recovery Diodes Deliver Low Loss Performance Together with Ultra-Low Noise Characteristics
RFL/RFS series improves power supply efficiency and reduces noise measures in air conditioners and EV charging stations
Willich-Münchheide, Germany, July 12, 2022 – ROHM has developed its 4th Generation 650V fast recovery diodes (FRDs), the RFL/RFS series, featuring low forward voltage (VF), fast reverse recovery time (trr) respectively, as well as ultra-low noise characteristics. The new devices are ideal for industrial and consumer equipment that handle large amounts of power, such as air conditioners and EV charging stations.
(Fig. 1)

In recent years, more effective use of electricity is necessary to cope with the rise in global power consumption. This is especially true for white goods and industrial equipment that handle large amounts of power such as EV charging stations. These require not only high electrical efficiency but also reducing workload for noise countermeasures in circuit design. In response, ROHM developed diodes that combine low VF for more efficient operation with fast trr characteristics that provide less loss and ultra-low noise during switching OFF.

Optimizing the device structure and materials allows the RFL/RFS series to achieve the optimum balance of VF and trr, which are important characteristics for FRDs but are in a trade-off relationship. The low VF RFL series reduces VF by approx. 3.2% and trr by about 8.3% over the conventional RFN series, while the high-speed RFS series VF by approx. 17.9% vs the conventional RFUH series. Both products contribute to higher power supply efficiency through optimal design based on circuit requirements. Furthermore, ultra-low noise diode recovery characteristics are achieved. They help to reduce both workload and components for noise.

Going forward, ROHM will continue to expand the package lineup of the RFL/RFS series to provide automotive support while expanding applicability by reducing power consumption.
(Fig. 2 + 3)

Product Lineup
RFL Series (Low VF Type)
(Fig. 4)

RFS Series (High-Speed trr Type)
(Fig. 6)

  • PFC (Power Factor Correction) circuits in air conditioners, washers, refrigerators, etc.
  • Secondary rectifier circuits in EV charging stations and the like
  • Inverter circuits in machine tool robots, compressors, etc.
  • Power supplies for servers, base stations, and more.
Circuit (Topology) Examples
(Fig. 6 – 8)

Topology Selection
When designing power supply circuits, it is necessary to select a circuit configuration (topology) that matches the required specifications for input/output voltages, power, isolation, and other factors. ROHM offers a selection page that recommends the optimum products for various topologies.

Availability: Now (In mass production)
Available for purchase through online distributors Digi-Key, Mouser, and Farnell.

About ROHM Semiconductor
ROHM Semiconductor is a global company of 452.1 billion Yen (3.3 billion Euros) per March 31st, 2022, with over 23,000 employees. The company develops and manufactures a very large product range from SiC Diodes and MOSFETs, Analog ICs such as Gate Drivers and Power Management ICs to Power Transistors and Diodes to Passive Components. The production of our high performing products is taking place in state-of-the-art manufacturing plants in Japan, Germany, Korea, Malaysia, Thailand, the Philippines, and China. ROHM Semiconductor Europe has its Head Office near Dusseldorf serving the EMEA region (Europe, Middle East and Africa). For further information, please contact
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» Press Release
Date: 12.07.2022 14:00
Number: PR15/22EN
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ROHM’s New 4th Gen Fast Recovery Diodes Deliver Low Loss Performance Together with Ultra-Low Noise Characteristics

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Fig. 8
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