85-VAC - 400-VAC input multiple output flyback reference design
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Key Document


This offline flyback reference design uses the UCC28700 controller to generate 2 isolated outputs (12 V at 1.2 A, -3.3 V at 10 mA) from an AC input (85 VAC - 400 VAC). The controller provides accurate voltage and current regulation with primary-side feedback, eliminating the need for opto-coupler feedback circuits. The valley-switching technique reduces switching losses and keeps the efficiency high.

  • 85 VAC - 400 VAC input to 2 isolated outputs
  • Valley-switching operation for high overall efficiency
  • Primary-side regulation eleminates opto-coupler
  • Precise control of output voltage and current

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(Output Voltage 1)
(Output Voltage 2)
Vin (Min) (V)8585
Vin (Max) (V)400400
Vout (Nom) (V)12-3.3
Iout (Max) (A)1.1.01
Output Power (W)13.2.033
Input TypeACAC
TopologyFlyback- CCMFlyback- CCM

TI Devices (2)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
TPS723  200-mA, negative, adjustable low-dropout voltage regulator with enable  Power management  Sample & Buy View 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)
TPS723 Download Download
UCC28700 Download Download

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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 9192 12 Dec 2018
Design files (6)
Title Type Size (KB) Date
ZIP 700 12 Dec 2018
ZIP 700 12 Dec 2018
PDF 200 12 Dec 2018
PDF 191 12 Dec 2018
PDF 33 12 Dec 2018
PDF 140 12 Dec 2018

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