High Voltage Input (184Vac…707Vac) to 12V@1A, 3.3V@100mA Non-isolated Flyback Reference Design


Design files


The UCC28720 is a quasi resonant controller and is specialized to drive high voltage BJTs. When the drain voltage is higher than 1KV, BJTs are the best choice for low to mid power flyback converters. In this case two voltages are supplied: 12V@1A and 3.3V@100mA.

  • Over 84% efficiency at full load
  • Over 70% efficiency at 10% load
  • Provides 12V and 3.3V outputs
  • Works continuously up to 440Vac input and survives 1KVpeak surge
Output voltage options PMP8678.1 PMP8678.2
Vin (Min) (V) 185 185
Vin (Max) (V) 700 700
Vout (Nom) (V) 3.3 12
Iout (Max) (A) .1 1
Output Power (W) .33 12
Isolated/Non-Isolated Non-Isolated Non-Isolated
Input Type DC DC
Topology Buck- Integrated Switch Flyback- Quasi Resonant
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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.

SLUUB38.PDF (849 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

SLUC556.ZIP (52 K)

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


Includes TI products in the design and potential alternatives.

Buck converters (integrated switch)

TPS56020017V Input, 500mA Synchronous Step-Down Regulator in SOT-23 with Advanced Eco-Mode™

Data sheet: PDF | HTML
Flyback controllers

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

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
Test report PMP8678 Test Results Oct. 20, 2014

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