Dual-Output LM5161-Q1 Fly-Buck™ Reference Design With an Ultra-Small Coupled Inductor


Design files


PMP15007 uses the LM5161-Q1 in a Fly-Buck topology with the primary and secondary output both set to 5V nominal. The circuit accommodates a voltage input range from 36V to 72V, ideal for the 48V nominal input rail. While the primary side is set at 5.32V nominally, the secondary isolated side sees 5V when using feedback resistors and 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 225 mA each.  The switching frequency is set at 315 kHz nominal.

  • 36V to 72Vin, 5V @225mA (dual) output, 2.25W (one non-isolated primary and one isolated secondary)
  • ~75% peak efficiency
  • Compact and cost effective isolated solution with an off-the-shelf coupled inductor instead of custom transformer
  • Solution size: 32 mm x 22 mm (1.25 in. x 0.9 in.); max component height: 3.5 mm
  • 3.5 mm max height of coupled inductor helps in height-constraint applications
Output voltage options PMP15007.1 PMP15007.2
Vin (Min) (V) 36 36
Vin (Max) (V) 72 72
Vout (Nom) (V) 5 5
Iout (Max) (A) .225 .225
Output Power (W) 1.125 1.125
Isolated/Non-Isolated Non-Isolated Isolated
Input Type DC DC
Topology FlyBuck FlyBuck
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

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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

TIDROG2.ZIP (2138 K)

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.

AC/DC & DC/DC converters (integrated FET)

LM5161-Q1Wide Input 4.5-V to 100-V, 1-A Synchronous Buck / Fly-Buck Converter

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Test report PMP15007 Test Results Nov. 03, 2016

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