58-VAC - 255-VAC 3-phase input multiple output flyback reference design
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Key Document


This offline flyback reference design uses the LM5021 controller to generate 3 isolated outputs (12 V at 705 mA, 12 V at 733 mA, 35 V at 25 mA) from an 3 phase AC input (58 VAC - 255 VAC). The DC input voltage range is between 100 V and 623 V. The design can provide 18-W output power. The LM5021 uses an optical coupler to regulate the 12-V output and to improve transient response. The controller operates with a fixed frequency of 100kHz.

  • 3 phase input, which allows a very wide input voltage range
  • Achieves over 85% efficiency at high line
  • Optocoupled feedback for constant voltage regulation
  • Output overvoltage protection with latch, in case of loop opto fail

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(Output Voltage 1)
(Output Voltage 2)
(Output Voltage 3)
Vin (Min) (V)100100100
Vin (Max) (V)623623623
Vout (Nom) (V)121235
Iout (Max) (A).705.733.025
Output Power (W)8.468.796.875
Input TypeDCDCDC
TopologyFlyback- CCMFlyback- CCMFlyback- CCM

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
LM5021  30V, 1MHZ current mode PWM controller  Offline & isolated DC/DC controllers & converters  Sample & Buy Not Available

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
ATL431 Download Download
LM5021 Download Download
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Technical documentation

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User guides (1)
Title Type Size (KB) Date
PDF 10624 21 Dec 2018
Design files (6)
Title Type Size (KB) Date
ZIP 153 21 Dec 2018
ZIP 818 21 Dec 2018
PDF 238 21 Dec 2018
PDF 624 21 Dec 2018
PDF 32 21 Dec 2018
PDF 190 21 Dec 2018

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