3.5W isolated push-pull reference design for auxiliary power supply
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This reference design is an isolated open-loop push-pull with “cascode” FETs that finds its typical application in isolated gate drive supply. The cascode connection extends the input voltage range of SN6505B from 5 V to 24 V, and two outputs supply 15 V at 120 mA and 5 V at 350 mA. Its 2-mm transformer makes the solution ultra-thin.

  • Low-noise, high-voltage isolation
  • No loop compensation (open loop)
  • Suitable for multi-output applications
  • No inductor on secondary side

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Schematic/Block Diagram

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Design Files

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(Output Voltage 1)
(Output Voltage 2)
Vin (Min) (V)21.621.6
Vin (Max) (V)26.426.4
Vout (Nom) (V)515
Iout (Max) (A).35.12
Output Power (W)1.751.8
Input TypeDCDC
TopologyForward- Push PullForward- Push Pull

TI Devices (1)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
SN6505B  Low-noise, 1-A, 420-kHz transformer driver with soft start for isolated power supplies  Power for signal isolators  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
SN6505B Download Download

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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 1532 06 May 2019
Design files (6)
Title Type Size (KB) Date
ZIP 19 06 May 2019
ZIP 361 06 May 2019
PDF 324 06 May 2019
PDF 603 06 May 2019
PDF 91 06 May 2019
PDF 86 06 May 2019

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