Dual-Output Isolated Fly-Buck Reference Design With an Ultra-Small Coupled Inductor


Design files


PMP15005 uses the LM5160 in a Fly-Buck™ topology with the primary and secondary output both set to 5V nominal. The circuit accommodates a voltage input range from 14V to 36V, ideal for the 24-V nominal input rail. While the primary side is set at 5.4V nominally using the feedback resistors, the secondary isolated side sees 5V, which is based on Coilcraft’s LPD8035V series coupled inductor set at a turns-ratio of 1:1. The maximum operating current on both the primary and secondary rails are set at 225mA each.  The switching frequency is set at 300 kHz nominal.

  • 14V to 36Vin, +5V @225mA (dual) output, 2.25W (one non-isolated primary and one isolated secondary
  • ~85% peak efficiency
  • Compact and cost effective isolated solution with an off-the-shelf coupled inductor instead of custom transformer
  • Solution size: 32 x 22 mm (1.25 x 0.9 inch); max component height: 3.5mm
  • 3.5mm max height of coupled inductor helps in height-constraint applications
Output voltage options PMP15005.1 PMP15005.2
Vin (Min) (V) 14 14
Vin (Max) (V) 36 36
Vout (Nom) (V) 5 5
Iout (Max) (A) .225 .225
Output Power (W) 1.125 1.125
Isolated/Non-Isolated Isolated Non-Isolated
Input Type DC DC
Topology FlyBuck FlyBuck
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Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDUC31.PDF (845 K)

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


Detailed schematic diagram for design layout and components


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


Detailed overview of design layout for component placement


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


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


PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Isolated DC/DC converters & modules

LM5160LM5160 wide input 65V, 2A synchronous buck/Fly-Buck™ converter

Data sheet: PDF | HTML
Isolated DC/DC converters & modules

LM5160-Q1Wide Input 65V, 2A Synchronous Buck / Fly-Buck™ Converter

Data sheet: PDF | HTML
Isolated DC/DC converters & modules

LM5160ALM5160A Wide Input 65V, 2A Synchronous Buck / Fly-Buck™ Converter

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Test report PMP15005 Test Results LM5160 Fly Buck Jul. 25, 2016

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