Primary-Side Regulated Flyback with 85 to 265VAC Input (12V @ 0.5A) Reference Design
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Key Document


The PMP8787 reference design uses the UCC28700 flyback controller to generate a 12V/500mA output from a universal AC input. The primary-side regulation technique implemented by the UCC28700 eliminates the need for an opto coupler, reducing the size and cost of the design. In addition, the valley switching of the UCC28700 allows this design to achieve a maximum load efficiency over 80%; no load losses are less than 40mW. The circuit board measures only 28mm by 33mm, with a maximum height below 20mm.

  • Primary Side Regulation (no optocoupler)
  • Standby (no load) power consumption is less than 40mW
  • Conducted emissions are below Class B levels
  • Compact form factor 28mm X 33mm X 20mm

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Schematic/Block Diagram

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Design Guide

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Design Files

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(Output Voltage 1)
Vin (Min) (V)85
Vin (Max) (V)265
Vout (Nom) (V)12
Iout (Max) (A).5
Output Power (W)6
Input TypeAC
TopologyFlyback- Quasi Resonant
Flyback- DCM
Flyback- Non Sync

TI Devices (1)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
UCC28700  Constant-voltage, constant-current PWM with PSR & Programmable cable compensation  Offline & isolated DC/DC controllers & converters  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
UCC28700 Download Download

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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 1995 21 Mar 2016
Design files (5)
Title Type Size (KB) Date
PDF 99 21 Mar 2016
PDF 87 21 Mar 2016
PDF 95 21 Mar 2016
PDF 229 10 Mar 2013
ZIP 166 10 Mar 2013

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