1ch Buck Converter Integrated FET

This is the product guarantees long time support in Industrial market. The BD9G341AEFJ-LB is a buck switching regulator with integrated 150mΩ power MOSFET. Current mode architecture provides fast transient response and a simple phase compensation setup. The operating frequency is programmable from 50kHz to 750kHz. Additional protection features are included such as Over Current Protection, Thermal shutdown and Under voltage lockout. The under voltage lockout and hysteresis can be set by external resistor.

Product Detail

Part Number | BD9G341AEFJ-LBE2
Status | Recommended
Package | HTSOP-J8
Unit Quantity | 2500
Minimum Package Quantity | 2500
Packing Type | Taping
RoHS | Yes






Integrated FET / Controller

Integrated FET



Synchronous / Nonsynchronous












SW frequency(Max.)[MHz]




Operating Temperature (Min.)[°C]


Operating Temperature (Max.)[°C]


Package Size [mm]

4.9x6 (t=1)


  • Long Time Support Product for Industrial Applications
  • Wide input voltage range from 12V to 76V.
  • Integrated 80V/3.5A/150mΩ NchFET.
  • Current mode.
  • Variable frequency from 50kHz to 750kHz.
  • Accurate reference voltage. (1.0V±1.5%).
  • Precision EN threshold (±3%).
  • Soft-start function
  • 0µA Standby current
  • Over Current Protection (OCP),
    Under Voltage Lockout (UVLO),
    Thermal-Shutdown (TSD),
    Over Voltage Protection (OVP)
  • Thermally enhanced HTSOP-J8 package

Design Resources



White Paper

  • Industrial DC/DC Buck Converters BD9x Series
  • Cutting-Edge Web Simulation Tool “ROHM Solution Simulator” Capable of Complete Circuit Verification of Power Devices and Driver ICs

Technical Articles

Schematic Design & Verification

  • Buck DC/DC Converter Recommended Inductor List
  • Calculation of Power Dissipation in Switching Circuit
  • Considering Input Filter to Reduce Conducted Emissions by DCDC Converter
  • Considering Polarity of Power Inductor to Reduce Radiated Emission of DC-DC converter
  • Method for Monitoring Switching Waveform
  • PCB Layout Techniques of Buck Converter
  • Phase Compensation Design for Current Mode Buck Converter
  • Method for Determining Constants of
  • Power Supply Sequence Circuit with General Purpose Power Supply IC
  • Suppression Method of Switching Noise Using Linear Regulator and Low Pass Filter
  • Diode Selection Method for Asynchronous Converter
  • Measurement Method for Phase Margin with Frequency Response Analyzer (FRA)
  • Usage of SPICE Macromodel for DC/DC
  • Snubber Circuit for Buck Converter IC
  • Efficiency of Buck Converter
  • Calculation of Power Loss (Synchronous)
  • Inductor Calculation for Buck converter IC
  • Considerations for Power Inductors Used for Buck Converters
  • Capacitor Calculation for Buck converter IC
  • The Important Points of Multi-layer Ceramic Capacitor Used in Buck Converter circuit
  • Resistor Value Table to set Output Voltage of Buck Converter IC
  • Importance of Probe Calibration When Measuring Power: Deskew
  • Impedance Characteristics of Bypass Capacitor

Thermal Design

  • What Is Thermal Design
  • Basics of Thermal Resistance and Heat Dissipation
  • Method for Calculating Junction Temperature from Transient Thermal Resistance Data
  • Notes for Temperature Measurement Using Thermocouples
  • Two-Resistor Model for Thermal Simulation
  • Notes for Temperature Measurement Using Forward Voltage of PN Junction
  • Thermal Resistance
  • Precautions When Measuring the Rear of the Package with a Thermocouple


Calculation Tools

This Calculation Sheet supports the application circuit design of switching regulators. The sheet has formulas necessary for determining peripheral parts. You can easily determine the circuit parameters that meet the desired characteristics by setting the values according to the guidance.
  • Calculation-sheet for the circuit theoretical formula - BD9G341AEFJ-LB


  • Unencrypted SPICE Model (Inquiry Form)
  • BD9G341AEFJ-LB SPICE Model


  • HTSOP-J8 Footprint / Symbol
  • HTSOP-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)