85 to 265VAC Input 12V/3W Low Cost Flyback with BJT Reference Design


Design files


This 12V/3W reference design is optimized for very low cost and yet maintains good efficiency. Two key factors for minimizing cost are a BJT is used for the main power switch, and primary-side regulation (PSR) eliminates the need for an optocoupler. The UCC28720 quasi-resonant flyback controller is able to implement both of these features.

  • Low cost BJT main switch
  • PSR eliminates cost of optocoupler and error amplifier
  • Conducted EMI data provided
Output voltage options PMP20744.1
Vin (Min) (V) 85
Vin (Max) (V) 265
Vout (Nom) (V) 12
Iout (Max) (A) .4
Output Power (W) 4.8
Isolated/Non-Isolated Isolated
Input Type AC
Topology Flyback

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.

TIDUCY8.PDF (2527 K)

Test results for the reference design, including efficiency graphs, test prerequisites and more

TIDRQ39.PDF (176 K)

Detailed schematic diagram for design layout and components

TIDRQ40.PDF (68 K)

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

TIDRQ41.PDF (126 K)

Detailed overview of design layout for component placement

TIDRQ43.ZIP (104 K)

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

TIDRQ42.PDF (480 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Flyback controllers

UCC28720Constant-voltage, constant-current controller with primary-side regulation for bipolar power devices

Data sheet document-pdfAcrobat PDF open-in-new HTML

Technical documentation

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Type Title Date
* Test report PMP20744 Test Results Feb. 27, 2017

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