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


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

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(Output Voltage 1)
(Output Voltage 2)
Vin (Min) (V)3636
Vin (Max) (V)7272
Vout (Nom) (V)55
Iout (Max) (A).225.225
Output Power (W)1.1251.125
Input TypeDCDC

TI Devices (1)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
LM5161-Q1  Wide Input 4.5-V to 100-V, 1-A Synchronous Buck / Fly-Buck Converter  Offline & isolated DC/DC controllers & converters  Sample & Buy View Design Kits & Evaluation Modules

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User guides (1)
Title Type Size (KB) Date
PDF 892 03 Nov 2016
Design files (6)
Title Type Size (KB) Date
ZIP 295 03 Nov 2016
ZIP 2138 03 Nov 2016
PDF 317 03 Nov 2016
PDF 98 03 Nov 2016
PDF 62 03 Nov 2016
PDF 202 03 Nov 2016

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