November 2010


Compact flyback transformers

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TDK-EPC, a group company of the TDK Corporation, presents a new series of compact SMD flyback transformers from EPCOS for space-saving power supplies. Thanks to their EFD cores, they enable insertion heights of only 8.65 to 14.8 mm, depending on the transformer type.

The new B82802* series comprises three core sizes and covers the power range between 12 and 55 W. These SMD flyback transformers are suited for input voltages of between 36 and 60 V at a clock frequency of 100 kHz and a duty ratio of up to 50 percent. In the standard versions, the output power is divided up among two or three windings. This results in voltages of 3.3 V at currents of 1.2 to 3.3 A; 5 V at 0.8 to 5.5 A and 12 V at 0.5 to 2.3 A. Customer-specific configurations of the output voltages and powers are also possible. The transformers are designed for an operating temperature of between -40 and +125 °C and tested for breakdown at 1500 V AC.


  • Flyback converter: a special switching converter topology. These DC/DC converters are also known as buck-boost converters. Their advantage lies in the electrical separation between input and output voltage. Flyback converters are used at powers of up to 250 watts.

Main applications

  • DC/DC converters for industrial and consumer electronics as well as communications technology.

Main features and benefits

  • Low insertion height of 8.65 to 14.8 mm
  • Powers up to 55 watts
  • Up to three output voltages

Key data


Vout1/ Iout1


Vout2/ Iout2


Vout3/ Iout3




Ordering code

EFD 155/ 1.212/ 0.512


EFD 153.3/ 1.25/ 0.812/ 0.3312B82802A0012A315
EFD 205/ 3.012/ 1.2530B82802A0030A220
EFD 203.3/ 3.05/ 2.012/ 0.8330B82802A0030A320
EFD 255/ 5.512/ 2.355B82802A0055A225
EFD 253.3/ 5.55/ 3.712/ 1.555B82802A0055A325



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