Compact SMT Current Sense Transformers For Power Electronics –Feb 29, 2016– Tokyo, Japan (Techreleased) – TDK Corporation presents two new series of EPCOS SMT current sense transformers for power electronics. The various types in the B78417A* series are based on EP7 ferrite cores, have compact dimensions of just 10.6 mm x 12.2 mm x 11.0 mm and are designed to measure pulse currents of up to 20 A.

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The maximum DC resistance on the primary winding is 1.9 mΩ. The SMT current sense transformers in the B78419A* series are designed with EP10 ferrite cores. These components have dimensions of 12.8 mm x 13.6 mm x 14.4 mm and their measurement range extends up to 30 A. The DC resistance is just 0.5 mΩ.

Each series is available with a variety of turn ratios: While the EP7-based transformers are available in four versions with turn ratios of between 1:50 and 1:125, the EP10 transformers offer five versions with turn ratios of between 1:50 and 1:180. The permissible operating temperature range extends from -40 °C to +150 °C. The transformers are suitable for measuring currents in the frequency range from 50 kHz to 250 kHz.

Possible applications include switch-mode power supplies and all types of converters. The test voltage between the primary and secondary sides is 2400 V AC and the creepage distances meet the requirements for basic insulation according to IEC 60664. As the components are qualified to AEC-Q200, they can also be used in xEV applications, e.g. for measuring the currents in DC/DC inverters.

Main applications

  • Switch-mode power supplies and all types of converters
  • DC/DC inverters in xEV applications
  • Current measurement in 48 volt on-board power supplies

Main features and benefits

  • Wide measuring range up to 30 A
  • Low ohmic resistance
  • Creepage distances according to IEC 60664 (basic insulation)
  • High dielectric strength for compact design
  • Qualified to AEC-Q200
  • Wide range of turn ratios

Key data

Type Dimensions
[mm]
Max. DC resistance
primary winding [mΩ]
Max. current
[A]
Turns
ratio
B78417A2285A003 10.6 x 12.2 x 11.0 1.9 20 1:50
B78417A2286A003 10.6 x 12.2 x 11.0 1.9 20 1:70
B78417A2185A003 10.6 x 12.2 x 11.0 1.9 20 1:100
B78417A2287A003 10.6 x 12.2 x 11.0 1.9 20 1:125
B78419A2288A003 12.8 x 13.6 x 14.4 0.5 30 1:50
B78419A2289A003 12.8 x 13.6 x 14.4 0.5 30 1:70
B78419A2251A003 12.8 x 13.6 x 14.4 0.5 30 1:100
B78419A2290A003 12.8 x 13.6 x 14.4 0.5 30 1:125
B78419A2271A003 12.8 x 13.6 x 14.4 0.5 30 1:180