18-72VDC Input, 12V/120W Active Clamp Forward Reference Design
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This reference design generates a 12V/10A output from a wide range 18V to 72V telecom input. The UCC2897A controls an active clamp forward converter power stage. The low gate charge and low RDSon of the CSD18533Q5A, implemented as a synchronous rectifier, provides for a highly efficient design. This design is laid out in a standard quarter brick footprint and achieves efficiencies near 95%.

  • High efficiency ~95% peak
  • Footprint compatible with standard 1/4 brick
  • Self-driven synchronous rectifiers reduce drive complexity
  • Lower cost solution compared to modules

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Schematic/Block Diagram

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Design Guide

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Design Files

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(Output Voltage 1)
Vin (Min) (V)18
Vin (Max) (V)72
Vout (Nom) (V)12
Iout (Max) (A)10
Output Power (W)120
Input TypeDC
TopologyForward- Active Clamp

TI Devices (2)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
CSD18533Q5A  60V, N ch NexFET MOSFETâ„¢, single SON5x6, 5.9mOhm  MOSFETs  Sample & Buy View Design Kits & Evaluation Modules
UCC2897A  110-V active clamp current mode PWM controller with P-channel clamp FET and line OV protection  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)
CSD18533Q5A VSONP (DQJ)| 8 Download
UCC2897A Download Download
Download Download

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Technical documentation

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User guides (1)
Title Type Size (KB) Date
PDF 2955 03 Nov 2017
Design files (6)
Title Type Size (KB) Date
PDF 100 03 Nov 2017
PDF 155 03 Nov 2017
ZIP 207 03 Nov 2017
ZIP 618 03 Nov 2017
PDF 672 03 Nov 2017
PDF 142 03 Nov 2017

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