Low Noise Quasi-Resonant Control DC/DC converter IC for AC/DC Converter

The BD7682FJ-LB is a quasi-resonant controller-type DC/DC converter optimized for products equipped with an electrical outlet. Quasi-resonant operation enables soft switching and helps to keep EMI low, while utilizing an external switching MOSFET and current detection resistor provides greater design flexibility. Additional features include a brown out function that monitors the input voltage for system optimization and a burst mode function for reducing power during light loads. Multiple protection functions are also incorporated to provide greater reliability, such as soft start, burst mode, per-cycle overcurrent limiter, and overvoltage/overload protection. A gate clamp circuit is built in as well for optimizing SiC MOSFET drive.

SCT2H12NZ(1700V SiC-MOSFET) and BD7682FJ-LB(AC/DC Converter IC) Evaluation Board
BD7682FJ-LB-EVK-402 [Input: AC 400-690V , Output: 24V DC]
Application Note , Presentation Document , Buy Evaluation Board
BD7682FJ-EVK-301 [Input: AC 210-480V DC 300-900V , Output: 12V DC]
Application Note, Evaluation Board User Guide, Quick Start Guide, Inquiry Evaluation Board

Product Detail

Part Number | BD7682FJ-LBE2
Status | Recommended
Package | SOP-J8
Unit Quantity | 2500
Minimum Package Quantity | 2500
Packing Type | Taping
RoHS | Yes




Controller Type






SW frequency(Max.)[kHz]








Light Load mode




Soft Start


Thermal Shut-down


Under Voltage Lock Out


Operating Temperature (Min.)[°C]


Operating Temperature (Max.)[°C]



  • Pin 8 : SOP-J8 Package (6.00mm × 4.90mm : 1.27mm pitch [TYP] )
  • Quasi-resonant type (low EMI)
  • Frequency reduction mode
  • Low current consumption (19µA), during standby
  • Low current consumption when no load (burst operation when light load)
  • Maximum frequency (120kHz)
  • CS Pin Leading-Edge Blanking
  • VCC UVLO (Under Voltage Drop Out protection)
  • VCC OVP (Over Voltage Protection)
  • Per-cycle over-current protection circuit
  • Soft start
  • ZT trigger mask function
  • Voltage protection function (brown out)
  • ZT OVP (Over Voltage Protection)
  • Gate-clamp circuit

Supporting Information




SiC is attracting much attention as a next-generation compound semiconductor due to its superior characteristics over silicon.。
Auxiliary power supplies used in high voltage, high power industrial equipment typically utilize high voltage (>1000V) silicon MOSFETs. But by replacing these with high efficiency SiC MOSFETs heat generation can be significantly reduced, eliminating the need for external parts such as heat sinks.
ROHM has recently expanded its considerable lineup by offering 1700V class SiC MOSFETs along with an evaluation board that facilitates performance verification and application development.

Evaluation Board

As a comprehensive semiconductor manufacturer, ROHM now offers ICs optimized for use with SiC devices, including the BD7682FJ-LB DC/DC converter control IC designed to maximize the performance of SiC power MOSFETs such as the SCT2H12NZ. An evaluation board (BD7682FJ-LB-EVK-402) integrating both products is also available.

Evaluation Power Supply Board(BD7682FJ-LB-EVK-402)

Key Features 1:Optimized for auxiliary power supplies in industrial equipment

Compared to 1500V silicon MOSFETs used in auxiliary industrial-grade power supplies, ROHM's SiC
power MOSFETs feature 8x lower ON resistance (1.15Ω) and a withstand voltage of 1700V. In addition, the TO-3PFM package delivers the necessary creepage distance (distance measured along the surface of the insulator) demanded by industrial equipment.

ON Resistance Comparison Application Example

Key Features 2:Achieve even higher efficiency by combining with ROHM's dedicated IC

AC/DC Inverter Efficiency Comparison: Si vs. SiC

Combining with ROHM's BD7682FJ-LB AC/DC converter control IC improves efficiency by up to 6% while minimizing heat generation, making it possible to simplify and reduce the size of heat dissipation components.


Part No. Package Polarity VDSS ID PD
NEW SCT2H12NZ TO-3PFM Nch 1700V 3.7A 35W 1.15Ω
NEW SCT2H12NY TO-268-2L 4A 44W
NEW SCT2750NY 5.9A 57W 0.75Ω


    • Evaluation Board
    • BD7682FJ-EVK-301
    • The AUX board is able to operate with both AC and DC input voltages. It is therefore possible to derive the power directly from the grid or from the system DC link

  • User's Guide Buy
    • Evaluation Board
    • BD7682FJ-LB-EVK-302
    • The BD7682FJ is an AC/DC quasi-resonant flyback controller IC from ROHM Semiconductor and offers an Auxiliary Power Supply Solution if combined with the 1700 V SiC MOSFET (SCT2H12NZ). The BD7682FJ and SCT2H12NZ combined together have been used to develop an isolated 100 W 24 V output auxiliary power solution with a very accurate voltage regulation.

  • User's Guide Buy
    • Evaluation Board
    • BD7682FJ-LB-EVK-402
    • BD7682FJ-LB-EVK-402 evaluation board outputs 24 V voltage from the input of 300 Vdc to 900 Vdc. The output current supplies up to 1 A. The BD768xFJ-LB series are Quasi-Resonant switching AC/DC converter for driving SiC (Silicon Carbide) MOSFET. Using external switching MOSFET and current detection resistors provides a lot of flexibility in the design.

  • User's Guide Buy

Design Resources



Quick Start Guide

User's Guide

  • BD7682FJ-EVK-402 Evaluation Board User's Guide
  • 100 W Auxiliary Power Supply Eval Board BD7682FJ-LB-EVK-302
  • BD7682FJ-EVK-301 Evaluation Board User's Guide

Application Note

  • BD7682FL-LB Application Note
  • Design Considerations on the Gate Driving Circuit of Quasi-Resonant Controller for 1700V SiC MOSFET

Technical Articles

Schematic Design & Verification

  • Importance of Probe Calibration When Measuring Power: Deskew
  • Impedance Characteristics of Bypass Capacitor

Thermal Design

  • Thermal Resistance



  • BD7682FJ-LB Footprint / Symbol
  • SOP-J8 Footprint / Symbol
  • SOP-J8 3D STEP Data

Packaging & Quality

Package Information

  • Package Information
  • Anti-Whisker formation

Manufacturing Data

  • Factory Information

Environmental Data

  • UL94 Flame Classifications of Mold Compound
  • Compliance with the ELV directive
  • REACH SVHC Non-use Declaration
  • RoHS Comission Delegated Directive

Export Information

  • The Export Control Order
  • Export Administration Regulations(EAR)