36~57-Vdc input, 5-V/4-A output isolated flyback with synchronous rectification reference design


Design files


This reference design is a 36~57-Vdc input, 5-V/4-A output isolated flyback converter using LM5155 and UCC24612. The switching frequency is 250 kHz. With the synchronous rectification controller UCC24612 and a MOSFET at the secondary side, the system achieves 89.29% peak efficiency at 36-V input, which is 3.86% higher than Schottky rectification. The temperature of the rectified MOSFET is 33 degrees Celsius lower than Schottky under full load output. The load regulation in the whole input range is within ±0.5%.

  • An isolated flyback with simple synchronous rectification solution
  • 250-kHz switching frequency
  • 89.29% peak efficiency
  • Low temperature rise of rectified component
Output voltage options PMP40569.1
Vin (Min) (V) 36
Vin (Max) (V) 57
Vout (Nom) (V) 5
Iout (Max) (A) 4
Output Power (W) 20
Isolated/Non-Isolated Isolated
Input Type DC
Topology Flyback- Synchronous

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.

TIDT144.PDF (3192 K)

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

TIDM270.PDF (192 K)

Detailed schematic diagram for design layout and components

TIDM271.PDF (99 K)

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

TIDM272.PDF (124 K)

Detailed overview of design layout for component placement

TIDM274.ZIP (834 K)

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

TIDCFO0.ZIP (1573 K)

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

TIDM273.PDF (598 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Boost controllers (external switch)

LM51552.2-MHz wide VIN, 1.5-A MOSFET driver, non-synchronous boost controller

Data sheet document-pdfAcrobat PDF open-in-new HTML
N-channel MOSFETs

CSD18514Q5A40-V, N channel NexFET™ power MOSFET, single SON 5 mm x 6 mm, 4.9 mOhm

Data sheet document-pdfAcrobat PDF open-in-new HTML
SR & load share controllers

UCC24612High-frequency multi-mode synchronous rectifier controller

Data sheet document-pdfAcrobat PDF open-in-new HTML
Shunt voltage references

TL431LIAdjustable precision shunt regulator with optimized reference current (pin layout: KRA)

Data sheet document-pdfAcrobat PDF open-in-new HTML

Technical documentation

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Type Title Date
* Test report 36~57-Vdc Input, 5-V/4-A Output Isolated Flyback Reference Design Oct. 17, 2019

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