Compact low-loss isolated four-output flybuck reference design


Design files


This four output flybuck reference design the LM25017 synchronous buck converter to provide four 3.3 V, 82.5 mW outputs. Each output has 1.25 kV isolation and is regulated to 1% accuracy. A low profile transformer and low BOM count create a compact solution size.

  • Four 1.25 kV isolation, which mitigates noise between outputs
  • 1% accuracy on each 3.3 V output, to meet high precision specifications
  • Compact design with low profile transformer, which allows for easy integration into end system
  • Less than 750 mW losses with all outputs at full load, which provides efficent power conversion
Output voltage options PMP21557.1 PMP21557.2 PMP21557.3 PMP21557.4
Vin (Min) (V) 19 19 19 19
Vin (Max) (V) 29 29 29 29
Vout (Nom) (V) 3.3 3.3 3.3 3.3
Iout (Max) (A) .025 .025 .025 .025
Output Power (W) .0825 .0825 .0825 .0825
Isolated/Non-Isolated Isolated Isolated Isolated Isolated
Input Type DC DC DC DC
Topology FlyBuck^Linear Regulator FlyBuck^Linear Regulator FlyBuck^Linear Regulator FlyBuck^Linear Regulator

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.

TIDT049.PDF (1862 K)

Test results for the reference design, including efficiency graphs, test prerequisites and more

TIDRY32.PDF (108 K)

Detailed schematic diagram for design layout and components

TIDRY33.PDF (91 K)

Complete listing of design components, reference designators, and manufacturers/part numbers

TIDRY34.PDF (82 K)

Detailed overview of design layout for component placement

TIDRY36.ZIP (452 K)

Files used for 3D models or 2D drawings of IC components

TIDCF38.ZIP (204 K)

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

TIDRY35.PDF (323 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

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Technical documentation

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Type Title Date
* Test report Compact Low-Loss Isolated Four-Output Flybuck Reference Design Dec. 17, 2018

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