Flyback Converter for LT3573/LT3574/LT3575/LT3748 

Würth Elektronik developed flyback transformers for the switching regulators:
LT3573, LT3574, LT3575 and LT3748

More than 60 different transformers are available in stock. The demo boards impress with their simple design and the need for less components around the IC, as usual. Aging of the typical optocoupler used in isolated flyback converter designs are past now, as these switching regulators work with a primary side sensing, instead of using an optocoupler.

Würth Elektronik offers a wide variety of demo kits, which each includes a demo board. This board can be adjusted to input and output requirements by changing only two resistors and the transformer. Therefore, it’s an easy and fast customized isolated switch mode power supply.

Characteristics 

  • Standard transformers for various output voltages/currents available    
  • Easy design of custom power supply due to standard circuit and change of transformers and two components for feedback loop    
  • Isolation voltage up to 2.5 kV    
  • Less external components needed    
  • Small board space    
  • Low cost    
  • No optocoupler needed!    
  • Long term reliability voltage control    
  • No aging    
  • Same external parts for different output voltages    

Applications

  • PoE, Voice over IP, Communications  
  • Standby & industrial power supplies  
  • Xenon flash lamps, laser, LED lighting  
  • IGBT controller  
  • Sensitive input voltage required applications (small VP-P)  

Application Notes

Assembled demo boards with option to change included transformer 
Order Code* LT IC Demoboard Power (W) Transformer assembled on board
Order Code 		Ouput Voltage Transformer 2**
Order Code 		Ouput Voltage Transformer 3**
Order Code 		Ouput Voltage
750 105 LT3574 DC1636A 2.5 750 370 041 5 V / 0.35 A 750 311 304 3.3 V / 0.7 A 750 310 799 12 V / 0.15 A
750 103 LT3573 DC1228A 7 750 970 047 5 V / 1 A - - - -
750 106 LT3575 DC1643A 10 750 311 675 5 V / 1.4 A 750 310 564 12 V / 0.5 A 750 310 559 3.3 V / 1.5 A
750 107 LT3748 DC1557A 12 750 311 439 12 V / 1 A 750 310 688 3.3 V / 4 A 750 311 689 5 V / 3 A
750 108 LT3748 DC1694A 30 750 311 607 12 V / 2.5 A 750 311 599 15 V / 2 A 750 311 608 24 V / 1.3 A

Have a look at the electrical properties ...

Data Sheets

Design Tipps 

Schematics 

Additional Tools

Additional tools for selecting power inductos, HF inductors, SMD ferrites & transformers you can find here .