5-V/2-A, 12-V/2.5-A Dual-output flyback reference design with <50-mW standby power
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Key Document


This reference design is a dual-output flyback converter using secondary-side regulation based on the UCC28742. A 5-V rail is regulated within ±1% precision and a cross regulation of a 12-V rail is within -8% to +14% at 25% to 100% load. The design utilizes a single-layer PCB for cost optimization. The peak efficiency is 82.82% at 115 V/50 Hz and 83.19% at 230 V/50 Hz. Power consumption at standby mode is 31.6 mW at 115 V/50 Hz and 54.2 mW at 230 V/50 Hz.

  • <50-mA standby power consumption for 50-W power supply applications
  • Optocoupler feedback delivers fast transient response and tight voltage regulation
  • DCM operation with valley switching for improved efficiency and reduced EMI
  • Ultra-low startup current and large VDD  hysteresis for low bias capacitance
  • Fault protections, including input low line, output overvoltage, overcurrent, and short-circuit protection

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(Output Voltage 1)
(Output Voltage 2)
Vin (Min) (V)8585
Vin (Max) (V)264264
Vout (Nom) (V)125
Iout (Max) (A)2.52
Output Power (W)3010
Input TypeACAC
TopologyFlyback- Non SyncFlyback- Non Sync

TI Devices (2)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
ATL431  2.5-V low-IQ adjustable precision shunt regulator  Voltage references  Sample & Buy View Design Kits & Evaluation Modules
UCC28742  High-Efficiency Flyback controller With Optocoupler Feedback  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)
ATL431 Download Download
UCC28742 Download Download

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Technical documentation

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User guides (1)
Title Type Size (KB) Date
PDF 5119 02 Jul 2019
Design files (6)
Title Type Size (KB) Date
ZIP 209 02 Jul 2019
ZIP 525 02 Jul 2019
PDF 809 02 Jul 2019
PDF 81 02 Jul 2019
PDF 164 02 Jul 2019
PDF 165 02 Jul 2019

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