ECO7703 Datasheet | Philips Semiconductors

TECHNICAL PUBLICATION Power transformers for the frequency range of 30 - 80 MHz ECO7703 w w w t a .D S a e h U 4 t e .c m o w w w .D a S a t e e h U 4 t m o .c Philips Semiconductors Power transformers for the frequency range of 30 - 80 MHz CONTENTS 1 2 3 4 5 6 7 8 8.1 9 ABSTRACT SUMMARY INTRODUCTION CHOICE OF CORE MATERIAL POWER HANDLING CAPABILITY DETERMINATION OF THE NUMBER OF TURNS WINDING LOSSES PRACTICAL EXAMPLE Reference: APPENDIX Technical Publication ECO7703 1998 Mar 23 Philips Semiconductors Power transformers for the frequency range of 30 - 80 MHz 1 ABSTRACT Technical Publication ECO7703 In this report design information is given for transformers with a power handling capability up to 300 W in the frequency range of 30 - 80 MHz. The most suitable core material is ferrite type 4C6. The efficiency of these transformers is typically 98%. 2 SUMMARY In this frequency range only transmission line transformers can be used. For the windings coaxial cables with P.T.F.E. isolation are remended. The size of the core is based on a 1% power loss and a dissipation of 350 m W/cm3 corresponding with a flux density of 6 Gauss at 80 MHz. The required number of turns is determined by the ratio RP/L = 860 Ω/µH in which RP is the loss resistance and L the inductance in parallel with the input or output terminals. In the appendix the relation between the above mentioned quantities is derived. In the report a practical example is given of a symmetrical 1 : 4 impedance transformer with a power handling capability of 120 W. 3 INTRODUCTION In Ref.1 information was given on the design of power transformers mainly intended for the frequency range of 1.6 to 28 MHz. In this report some additional information will be presented for the frequency range of 30 to 80 MHz. 4 CHOICE OF CORE MATERIAL The best available ferrite for this frequency range is 4C6. In this material a series of toroids can be obtained in different sizes according to Table 1. Table 1...