Skip to main content
shopping_basket Basket 0
Log in

Reference Design -ROHM Buck DC/DC Converter BD9D321EFJ

The reference circuit design of DC/DC Converter BD9D321EFJ (124-6494)  (ROHM) was converted into Designspark PCB format. The BD9D321EFJ is a 4.5V to 18V input, 3.0A integrated MOSFET 1ch synchronous buck switching regulator.


Buck DC/DC Converter BD9D321EFJ

BD9D321EFJ is a synchronous buck switching regulator with built-in low on-resistance power MOSFETs. It is capable of providing current of up to 3A. The SLLM(TM) control provides excellent efficiency characteristics in light-load conditions which make the product appropriate for equipment and devices that demand minimal standby power consumption. External phase compensation circuit is not necessary for it is a constant on-time control DC/DC converter with high speed response.


  • Input Voltage Range: 4.5V to 18.0 V
  • Output Voltage Setting Range: 0.765V to 7V        (VIN×0.07)V to (VIN×0.65)V
  • Reference Voltage: 0.765V ± 1.5%
  • Output Current: 3 A (Max)
  • Switching Frequency: 700 kHz (Typ)
  • High Side MOSFET On-Resistance:100 m Ω (Typ)
  • Low Side MOSFET On-Resistance: 70 m Ω (Typ)
  • Standby Current: 2 μA (Typ)

What are included in the reference design file?

A Schematics design file (.sch), a PCB layout design file(.pcb), and parts library files for the design are provided. A RS part number and size information of parts are already linked to each part in the library. So you can directly order parts to RS by using the BOM quote feature, or can convert PCB files into 3D CAD data to design and simulate cases of boards. Of course, parts in the library would be used in another design. 



PCB layout


Parts library


Convert Designspark PCB designs into Designspark Mechanical 3D models


What is DesignSpark PCB format?

DesignSpark PCB is an award-winning software package for schematic capture and PCB layout, available for FREE from RS Components. Our software is easy to learn and use yet surprisingly powerful. DesignSpark PCB is now widely adopted in the industry as a standard format for design file sharing and collaboration. This is especially useful in the prototyping phase where most of the innovation takes place. Not yet a DesignSpark PCB user? 



k_uym has not written a bio yet…
DesignSpark Electrical Logolinkedin