Transformers for Switching Power Supplies
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• All specifications are subject to change without notice. • Conformity to RoHS Directive: This means that, in conformity with EU Directive 2002/95/EC, lead, cadmium, mercury, hexavalent chromium, and specific bromine-based flame retardants, PBB and PBDE, have not been used, except for exempted applications. Transformers for Switching Power Supplies Type: Issue date: LQ(Horizontal type) 20EG(Vertical type) 24EG(Vertical type) 26EG(Vertical type) 28EG(Vertical type) 34EG(Vertical type) EG(Horizontal type) September 2008 Pin terminal type(For single output) Pin terminal type(For multiple outputs) SRW series

(1/16) 002-01 / 20080919 / e6355_srw.fm • All specifications are subject to change without notice. Switching Power Supply Transformers SRW Series Development Concept Our newly developed transformers and chokes feature a new core shape using a new core material that is designed for different core usages based on the advantages of each material’s characteristics. Our lineup of transformers (small, thin, or inexpensive) allows us to provide the best transformer for your needs. We can also provide different transformer shapes not shown in the catalog, so feel free to contact us. CONCEPT...

(3/16) 002-01 / 20080919 / e6355_srw.fm • All specifications are subject to change without notice. For Single Output (Horizontal Type) LQ Series This series uses the new ferrite material, PC47, which has low loss and high-saturation magnetic flux density that prevents thermorunaway. This material allows for a low profile, single output switching power supply transformer, which means it can be mounted in very narrow spaces. FEATURES • The new high B, low loss PC47 material allows for the product to be smaller • Uses a newly developed LQ core for small switching power supply transformers •...

(4/16) 002-01 / 20080919 / e6355_srw.fm • All specifications are subject to change without notice. For Multiple Outputs (Vertical Type) 20EG Series This series uses the new ferrite material, PC47, which has low loss and high-saturation magnetic flux density that prevents thermorunaway. This transformer is for small, multiple output switching power supplies with a maximum output from 10 to 15W, and has a perfect balance between the core volume and coil share. FEATURES • The new high B, low loss PC47 material allows for the product to be smaller • This transformer uses a newly developed EGG...

(10/16) 002-01 / 20080919 / e6355_srw.fm • All specifications are subject to change without notice. Transformer Inductors for Power Supplies Standard GAP In order to respond to our customers’ requested delivery dates and costs, TDK can provide standard GAP products (indicated by " " in the below chart) for each shape. Please contact us about other GAP products separately. STANDARD AL-Value Core shape and size AL-value(nH/N2) R10 Series 160 200 250 315 400 500 R20 Series 160 180 200 224 250 280 315 400 450 500 R40 Series and other specialty products 160 180 200 224 250 280 315 325 350 375...

(11/16) 002-01 / 20080919 / e6355_srw.fm • All specifications are subject to change without notice. Specifications SPECIFICATIONS GENERAL CHARACTERISTICS RELIABILITY TESTSRELIABILITY TESTS • The above listed items are representative examples. The details can be found by referring to the appended individual delivery specifications. Temperature ranges Operating –10 to +60°C Storage –25 to +85°C Humidity ranges Operating 30 to 95(%)RH[without dewing] Storage 30 to 95(%)RH[without dewing] Standard test conditions Ambient temperature range +5 to +35°C Relative humidity range 45 to...

(12/16) 002-01 / 20080919 / e6355_srw.fm • All specifications are subject to change without notice. Design reference for switching power transformers • Maximum allowable Temperature The maximum allowable Temperature of SRW series transformer is classified in E class (120°C) in Japan. However, due to the fact that there is no classification known as E class in North America, it is classified in class 105 (105°C). • Temperature rise in Transformers In normal design condition, 55°C or less (using the resistance method) is the target of temperature rise of windings. Therefore, the maximum...

(14/16) 002-01 / 20080919 / e6355_srw.fm • All specifications are subject to change without notice. • Determining of secondary winding (1)Flyback converter As it is necessary to consider the voltage drop of the rectifier diode on the secondary side, Where, Vf: Voltage drop of the rectifier diode (2) Forward converter Output filter inductor must be used at secondary side in the forward converter, the voltage drop of the inductor also need to be considered, resulting, Where, VL: Voltage drop of the Output filter inductor • Example of drive waveforms Ringing choke system circuit (RCC)...

(15/16) 002-01 / 20080919 / e6355_srw.fm • All specifications are subject to change without notice. • In order for designing the transformer, the following conditions are necessary. It is greatly appreciated customer give us those conditions by filling out required information with the appended “Transformer specifications / inquiry form”. (1)Circuit topology Flyback type, forward type, push-pull, half-bridge, etc (2)Input voltage range The lower limit of rectified voltage is important, in particular. (3) Operating frequency It is especially necessary to determine the lower limit frequency...

(16/16) 002-01 / 20080919 / e6355_srw.fm • All specifications are subject to change without notice. 1. Company name 2. Department, applicant's name 3. Circuit system Prototype No: 4. Input specifications AC input voltage: Rated Operating range: DC input voltage: Rated Operating range: 5. Output voltage/Current/Diode used (diode voltage drop) Rectifier diode F.R.D: First Recovery Diode, S.B.D: Schottky Barrier Diode ERequest for connection method Yes No (When checking "Yes", please attach a drawing separately.) EPin assignments changes Possible Impossible 6. Clock frequency ( Flexible /...