ROHM 8-Channel Multi-Rail DC/DC Converter Board

Table of contents



{tabbedtable} Tab LabelTab Content


With increasing the number of automotive on-board units and the number of required functions, the electronic circuits of ADAS/Infotainment peripheral units require more complex designs.


  • The number of cameras, sensor units and mounted electronic components have increased, resulting in more complex power supply rails.
  • A highly efficient power supply system is necessary
  • Different noise standards (e.g., CISPR25 Class 5) that have to complied with for automotive units and many design elements other than functional design that have to be catered for.
  • In order to improve the safety function as a unit or system, it is necessary to have a function to monitor the power rail, detect the failure of the electronic circuit, and transmit it to the CPU.


To adapt these market requirements, ROHM has developed a reference design that satisfies the design elements cited above.


Description of Reference Design Board

This reference design board is a power tree solution board developed for infotainment devices such as automotive clusters and center information displays and for ECUs for ADAS application. The power system that can support functional safety is integrated on a single board to achieve the optimal configuration as a power tree. Excellent EMC performance that meets CISPR25 Class 5 even at all power supply rails are enabled, and reduces heat generation of each device by distributing high-efficiency DCDCs. In addition, two supervisor ICs with self-diagnosis functions can monitor the output of all power rails and contribute to a higher level of functional safety.


Overview of Reference Design Board

  • Provides the necessary power systems for ADAS and Infotainment applications with an eight circuit power tree.
  • Built-in Primary(*1) DC/DC Converter ICs (BD9P series) for stable power supply even immediately after battery cranking.
  • Built-in Secondary(*1) DC/DC Converter ICs (BD9S series) with an industry-leading small and highly efficient.
  • Built-in Power Supply monitoring IC with self-diagnostic functions that monitors the all eight output rails to contribute to improve functional safety level.
  • The following items were validated in the system level.
    • Standard Electrical Characteristics test
    • EMC test (CISPR25 Class 5 compliant without input filter)
    • Thermal performance test (separate located high-efficiency DC/DC converters distribute the heat)
  • On-board ICs and discrete parts are automotive AEC-Q100 or AEC-Q101 grade compliant.
  • Main ICs are functional safety products in the FS supportive(*2) category.



(*1) Primary, Secondary

In a multi-rail power system, the first stage conversion circuit from the battery or other power

source is called the Primary. The second stage conversion circuit connected to the output of

the primary is called the Secondary.


(*2) FS supportive

ROHM categorizes the forms that can be provided for functional safety by product. The

component-level forms are necessary to achieve functional safety in the unit.

For detail information:


Block Diagram


Functional Blocks


Bill of Materials

See related components List on the right column of this page.


Additional Information

Important Dates

Enrollment Begin: Aug 24 2021

Enrollment Ends: Oct 1 2021

RoadTesters Selected: Oct 14 2021 (estimated)

Product Shipped: Oct 15 2021

RoadTesting Begins: Oct 22 2021

Reminder/Update Email: Nov 22 2021

Submit Reviews By: Dec 22 2021

*The element14 RoadTest Staff will send this reminder/update email.

**If a RoadTester is unable to meet the deadline, please notify the RoadTest Program Lead, , as soon as possible before the deadline.


How to locate the official RoadTest review form:  How To Locate the Official RoadTest Review Form (duplicate)


(due date Dec 22 2021)

(due date Dec 22 2021)

  (due date Dec 22 2021)

(due date Dec 22 2021)

due date Dec 22 2021)

Terms and Conditions

ROHM 8-Channel Power Tree Reference Design– RoadTest

Terms and Conditions

These are the terms and conditions which govern the ROHM 8-Channel Power Tree Reference Design RoadTest contest. This Contest requires participants to submit an application indicating their previous experience with this type of equipment/component, information on what they would do to test the equipment/component, and the applicant’s desire to post a thorough review of their experience with images, photos, or other supplemental materials. Participants will be required to meet the Conditions for Participation.  The winners of this RoadTest will receive the item(s) listed below. RoadTest Reviews are due no later than 60 days after the receipt of the item(s). No other prizes are offered.

The Principal terms of the Competition:

The following words and phrases are used in these terms and conditions and have the meanings given to them below.


Key dates:

Applications Close: midnight (GMT) on Oct 1 2021

Announcement of Winner (estimated): Oct 4  2021

Prize: ROHM 8-Channel Power Tree Reference Design

Additional Prizes: none

Competition Site:

Site or element14 Community:

Judges: members of the element14 community team chosen at the Organiser’s discretion.

Judging Criteria, All of the following which will have equal weighting:

· Demonstrated competence with the technologies including links or descriptions of past projects

· Qualifications as indicated by current job role and/or schooling/vocational training;

· A thorough description of how the prize would be tested;

· Likelihood that the Applicant will blog about the prize and provide a review on;

· Originality;

· Innovation.

Organiser: Premier Farnell plc (registered in England and Wales under company number 876412) whose registered office is at Farnell House, Forge Lane, Leeds, UK

Conditions for Qualification: in addition to meeting the requirements of these terms, all persons applying to take part in the Contest (each one an Applicant) must:

· Provide a RoadTest application describing what he/she would do if awarded the Prize including similar previous projects, product experience and qualifications

Terms: these terms and conditions which govern the Competition and to which the Organiser reserves the right to make changes from time to time and the latest version of these Terms from time to time will be posted to the Site.

  1. Eligibility
  2. Applications:
  3. Selecting Winners:
  4. Liability:
  5. General:

1.1 Save as set out in these Terms, the Contest is open to any natural or legal person, firm or company or group of natural persons or unincorporated body.

1.2 All Applicants must be aged at least 18 at the time of their application.

1.3 Applicants must not enter the RoadTest if doing so or taking part may:

1.3.1 cause the Organiser and/or themselves to be in breach of any agreement (including but not limited to any contract of employment) to which they are a party or in breach of any law, regulation or rule having the force of law to which the Organiser or the Applicant may be subject or any policy of the Organiser or the Sponsor;

1.3.2 Require the Organiser to obtain any licence, authorisation or permission to deal with the Applicant; or

1.3.3 Be in breach of any policy or practice of their employer. Some employers prohibit or restrict their employees from taking part in competitions such as these or receiving prizes under them and the Organiser respects those policies and practices.

The Organiser reserves the right to disqualify any Application made in breach of these Terms and to reject any Application which it reasonably believes may be or become in breach. The Organiser reserves the right to require evidence in such form as the Organiser may reasonably require of any Applicant’s compliance with any of these Terms and to disqualify any Applicant or Participant who cannot provide such evidence reasonably promptly.

1.4 Multiple applications are not permitted.

1.5 Applications may not be submitted by an agent whether acting on behalf of an undisclosed principal or otherwise.

1.6 The Contest is NOT open to:

1.6.1 Any person or entity who is a resident or national of any country which is subject to sanctions, embargoes or national trade restrictions of the United States of America, the European Union or the United Kingdom;

1.6.2 Any employee, director, member, shareholder (as appropriate) or any of their direct families (parents, siblings, spouse, partner, children) (“Direct Families”) of the Organiser and Sponsors; or

2.1 Each Applicant must fully complete and submit a RoadTest Application by the Application Close.

2.2 By submitting a Registration Form, each Applicant:

2.2.1 Authorises the Organiser to use his or her personal data (as defined in the Data Protection Act 1998) for the purposes of running and promoting the RoadTest;

2.2.2 Authorises the Organizer to copy, reproduce and publish their application should they be accepted as a Participant;

2.2.3 Will be deemed to have read, accepted and agree to be bound by these Terms. Applicants are advised to print and keep safe these Terms;

2.2.4 Authorises the Organiser to copy, reproduce and use the Application and/or Review for the purposes of the RoadTest and as otherwise contemplated by these Terms. The Organiser will not be responsible for any inaccuracy, error or omission contained in any reproduction or use of the Project Blogs.

2.2.5 Licenses the Organiser to use the intellectual property in the Project (IP) for the purposes of this Contest. As between the Applicant and the Organiser the IP remains owned by the Applicant.

2.2.6 Grants the Organiser the right to use his or her likeness, photographs, logos, trademarks, audio or video recordings without restriction for the purposes of Contest or the promotion of it or the Site;

2.2.7 Agrees to participate positively in all publicity surrounding the Contest;

2.2.8 Agrees to be responsible for all expenses and costs incurred by him or her in preparing for, entering and participating in the Contest (save for any expenses expressly agreed by the Organiser to be borne by it in these Terms);

2.2.9 Confirms that he or she owns all IP used in his or her application or Project or Blogs and indemnifies the Organiser from any claim by a third party that use of any material provided by an Applicant to the Organiser infringes the intellectual property rights of any third party;

2.2.10 Agrees not to act in any way or fail to act in any way or be associated with any cause or group which would have a negative impact on the reputation of the Organiser and/or the RoadTest.

2.3 All applications submitted to this RoadTest must meet the following criteria:

2.3.1 Applicants must be the author, creator and owner of the proposed review idea. Applicants must not submit someone else’s idea;

2.3.2 The proposed application must be reasonably achievable by the within the time constraints of the Contest;

2.3.3 Applications must not include or propose any of the following, the inclusion of which shall render any proposed application ineligible:

(a) Applications which relate to socially taboo topics, such as illicit drug use or sexual gratification;

(b) Applications that are or could reasonably be considered to be illegal, immoral, discriminatory or offensive as determined by the Organiser;

(c) Applications in relation to them which if accepted would infringe or breach any of the policies or terms of access or use of the Site.

2.4 No Application may contain any of the hazardous substances identified by Article 4 of Directive 2002/95/EC of the European Parliament on the Restrictions on the Use of Substances in Electronic and Electrical Equipment ("the Directive") or the use of such hazardous substances in the in any such Project must not exceed the maximum concentration values set out in the Directive.

3.1 Winners will be selected by the Organiser on the basis of the quality of his or her application and its adherence to these Terms.

3.2 The total number of Winners selected will be at least the minimum number set out above but the actual number is at the sole discretion of the Organizer and/or the Sponsor, if applicable.

3.3 The Organiser will use all reasonable efforts to announce the Winners via an update to the RoadTest page by the date listed above.

3.4 Winners agree to take part in all publicity which the Organiser or the Sponsor wishes to use to promote the RoadTest, the Products featured or other Contests with which the Organiser may be connected from time to time.

3.5 Details of the Winners may also be published in the media.

3.6 Winners are responsible for all applicable taxes, duties or other charges payable in relation to any prize.


4.1 The Organiser hereby excludes all and any Liability arising out of the Contest or the acceptance, use, quality, condition, suitability or performance of any Prize, even where that Liability may arise from the Organiser’s negligence.

4.2 Nothing in these Terms will affect any Liability of the Organiser for death or personal injury arising from its negligence, for breach of Part II of the Consumer Protection Act 1987 (in the event that any entrant is entitled to claim rights under the Consumer Protection Act 1987) or for any matter in relation to which it would be illegal for the Organiser to exclude or to attempt to exclude its Liability.

4.3 Subject to 4.2, neither the Organiser, any parent company nor any subsidiary of the Organiser or such parent company or any of their directors, officers and employees (together referred to in these terms and the ‘Associates’) makes any guarantee, warranty or representation of any kind, express or implied, with respect to this Competition or the Prizes potentially available under it. Neither the Organiser nor any of its Associates shall be responsible for any Liability that may arise out of or in connection with person’s participation in this Competition, the claiming, redemption or value of any prizes under it, the use or enjoyment of such prizes or any events or circumstances arising out of or in connection with any of them. Any implied warranties of condition, merchantability or suitability or fitness for purpose of any of them are hereby expressly excluded. Wherever used in these Terms, ‘Liability’ shall mean any and all costs, expenses, claims, damages, actions, proceedings, demands, losses and other liabilities (including legal fees and costs on a full indemnity basis) arising directly or indirectly out of or in connection with the matter concerned.

5.1 The RoadTest is organised and sponsored by the Organiser. The Organiser reserves the right to delegate all or any of its powers, rights and obligations arising in relation to the RoadTest to any Associate and certain such rights and powers are assumed by the Organiser on behalf of itself and each Associate. Reference to “Organiser” shall be deemed to include reference to each Associate.

5.2 The RoadTest may be terminated at any time if there are, in the sole opinion of the Organiser, an insufficient number of entries, or if the Applications are not of an appropriate standard for a competition of this nature. The Organiser has the right to cancel or suspend the RoadTest at any time due to circumstances outside its reasonable control.

5.3 The Organiser shall have the sole discretion to disqualify (without correspondence or right of appeal) any Applicant it considers to be adversely affecting the process or the operation of the RoadTest or to be in breach of these Terms or to be acting in a disruptive manner or with intent to annoy, abuse, threaten or harass any other Applicant or Participant.

5.4 The Organiser has the right to amend or add to these Terms from time to time. Revised Terms and Conditions will be posted on the Contest Site and it is a condition of entry to the RoadTest that Applicants agree to comply with these Terms and, if appropriate, such Terms as amended from time to time.

5.5 Headings are for convenience only and do not affect the interpretation or construction of these Terms and Conditions.

5.6 These Terms and the operation of the Contest shall be governed by and construed in accordance with English Law and any claim or matter arising under these Terms shall be subject to the exclusive jurisdiction of the English courts.

Comment List
  • (due date Dec 22 2021)

      (due date Dec 22 2021)

    (due date Dec 22 2021)

    due date Dec 22 2021)


    If you have any content that's in progress, whether it's a RoadTest Review, Design Challenge application, blog, or other content that is 'saved as a draft' or in a 'draft status' then it will not be coming over to the new platform. Make sure you've either published your content, or saved the content that you currently have saved as a draft off the Community, as it will not be copied over to the new platform at all, before Friday the 5th of November 2021.

  •   wrote:


    Did look at this 2 weeks ago, but the board I should be designing* needs 5V for CAN, 3.3V, 1.2V for the MCU.

    So if I could adjust the 1.25V to 1.2V, but those resistors look like 0402, which I don't keep in stock.

    And I'd have to alter the power supervisor circuit as well, at least it's the same values of resistor.


    Ultimately I didn't have anything that needed the SoC outputs, and had other problems to deal with.


    * Semiconductor shortage means trouble finding a suitable DC-DC chip in stock.

    What are you going to use? Another power management IC, or a custom discrete design?

  • Did look at this 2 weeks ago, but the board I should be designing* needs 5V for CAN, 3.3V, 1.2V for the MCU.

    So if I could adjust the 1.25V to 1.2V, but those resistors look like 0402, which I don't keep in stock.

    And I'd have to alter the power supervisor circuit as well, at least it's the same values of resistor.


    Ultimately I didn't have anything that needed the SoC outputs, and had other problems to deal with.


    * Semiconductor shortage means trouble finding a suitable DC-DC chip in stock.

  • This is similar to what I need for my project in process, shame the rails arent trimmable, and are for a lower current application.


    This is the spec that I'm holding myself to:


    Use a 12V (11.1V) battery input - an OL & IOC  protected output at 5.1V  3+A to a Raspberry Pi

                                                       - an OL & IOC  protected output of 7V 3+A for servos and low power motor assemblies

                                                       - an OL & IOC protected output 5V 2A for sensors & displays

                                                        - an OL & IOC protected output 3.3V 2A for sensors & displays

  • I got some feedback regarding the original title for this roadtest: 8-channel power tree reference design.  The feedback I got is that it could be a bit more detailed. So, I took a closer look and came up with a new title: 8-channel Multi-rail DC/DC converter board.


    Randall Scasny

    RoadTest Program Manager



  • Note: This is a reference design board. The board was built for this roadtest.  


    We are not selling the boards yet, but the BOM is listed on the right/rail column of this page.


    Randall Scasny

    RoadTest Program Manager

  • The roadtest is open for enrollment.