120VAC Input, PSR 5V 25W Flyback Reference Design


Design files


This reference design is a 120Vac to 5V primary side regulated flyback converter with synchronous rectification on the secondary side.  The reference design has extremely low standby power at 67mW.  UCC28704 features integrated CC-CV regulation without the use of an optocoupler. PMP20771 utilizes synchronous rectification which improves system efficiency across the designed load range.

  • Over 88% efficiency at full load
  • Low standby power, 67mW with no load
  • 1oz, 2-layer board measuring 7mm x 38mm size
  • Primary side regulation eliminates the need for an optocoupler
Output voltage options PMP20771.1
Vin (Min) (V) 108
Vin (Max) (V) 132
Vout (Nom) (V) 5
Iout (Max) (A) 5
Output Power (W) 25
Isolated/Non-Isolated Isolated
Input Type AC
Topology Flyback- Synchronous

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.

TIDUDU0.PDF (2005 K)

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


Detailed schematic diagram for design layout and components


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


Detailed overview of design layout for component placement


Includes TI products in the design and potential alternatives.

Flyback controllers

UCC28704High-Efficiency Off-Line CV and CC Flyback Controller with Primary-Side Regulation (PSR)

Data sheet document-pdfAcrobat PDF open-in-new HTML
N-channel MOSFETs

CSD17559Q530-V, N channel NexFET™ power MOSFET, single SON 5 mm x 6 mm, 1.5 mOhm

Data sheet document-pdfAcrobat PDF open-in-new HTML
SR & load share controllers

UCC24636Synchronous rectifier controller With Ultra-Low Standby current

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

Technical documentation

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Type Title Date
* Test report PMP20771 Test Results Nov. 13, 2017

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