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

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(Output Voltage 1)
Vin (Min) (V)36
Vin (Max) (V)57
Vout (Nom) (V)5
Iout (Max) (A)4
Output Power (W)20
Input TypeDC
TopologyFlyback- Synchronous

TI Devices (4)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
CSD18514Q5A  40V, N ch NexFET MOSFETâ„¢, single SON5x6, 4.9mOhm  MOSFETs  Sample & Buy Not Available
LM5155  2.2MHz wide VIN non-synchronous boost controller  Step-up (boost) regulators  Sample & Buy View Design Kits & Evaluation Modules
TL431LI  Adjustable precision shunt regulator with optimized reference current (pin layout: KRA)  Voltage references  Sample & Buy Not Available
UCC24612  High-frequency multi-mode synchronous rectifier controller  Offline & isolated DC/DC controllers & converters  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
CSD18514Q5A VSONP (DQJ)| 8 Download Download
LM5155 Download Download
TL431LI Download Download
UCC24612 Download Download

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User guides (1)
Title Type Size (KB) Date
PDF 3121 17 Oct 2019
Design files (6)
Title Type Size (KB) Date
ZIP 1573 17 Oct 2019
ZIP 834 17 Oct 2019
PDF 598 17 Oct 2019
PDF 124 17 Oct 2019
PDF 99 17 Oct 2019
PDF 192 17 Oct 2019

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