Snubberless, Non-Isolated AC/DC Flyback Converter Reference Design with Simplified Transformer


Design files


TIDA-00628 is a 15V/6.5W non-isolated, single output, AC/DC Flyback power supply that is capable of operating from wide input voltage ranging from 85Vac to 440Vac. This design demonstrates 2 key features (1) the elimination of snubber components enabled by use of a high-voltage bipolar transistor and (2) simplified transformer design with no need for an auxilliary winding.  Low system parts count and built in advanced protection features result in a cost-effective solution for electricity meters and industrial designs.

  • Input voltage up to 440Vrms, 15V/6.5W output
  • No snubber - reduces BoM count and PCB area
  • BJT switch to reduce system cost
  • Non Isolated output allows simplified transformer with no auxilliary winding
  • Typical efficiency of 80% at 230V, 6.5W
  • Compliant with Conducted Emissions: CISPR 22, Class B
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.


Reference design overview and verified performance test data

TIDRH29.PDF (321 K)

Detailed schematic diagram for design layout and components

TIDRH30.PDF (40 K)

Complete listing of design components, reference designators, and manufacturers/part numbers

TIDRH31.PDF (108 K)

Detailed overview of design layout for component placement

TIDRH33.ZIP (953 K)

Files used for 3D models or 2D drawings of IC components


Design file that contains information on physical board layer of design PCB

TIDRH32.PDF (4281 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Flyback controllers

UCC28722Low-Cost CVCC Flyback controller With primary-side regulation for bipolar Power Device

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Design guide 6.5-W Snubberless Flyback Converter Using BJT Primary Switch Design Guide (Rev. A) Jan. 27, 2016
User guide TIDA-00628 Transformer Specification (Wurth Elektronik) Aug. 25, 2015

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