Inductors General Technical Information

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Inductors
General technical information

Date:

October 2008

Data Sheet

 EPCOS AG 2008. Reproduction, publication and dissemination of this publication, enclosures hereto and the information contained therein without EPCOS’ prior express consent is prohibited.

General technical information

1

Inductive components for electronic equipment

Inductive components store energy intermittently in switch-mode power supplies and DC/DC converters, form parts of RF circuits or RFID systems, match impedances, transform current/voltage, are filter elements and last but not least interference suppression components to ensure EMC. The requirements on inductors depend on how and where they are used. RF circuits need coils with high quality factors and resonant frequencies. EMC applications require high inductance to achieve good interference suppression characteristics, low Q factors being more desirable here due to the need to avoid resonance. EPCOS provides suitable inductive components for all applications. This data book contains a wide selection of standard components, from SMT types (starting with SIMID 0402) through 4-line highcurrent inductors for power electronics applications to transformers. Attention is drawn to the excellent RF characteristics and extremely high reliability of the components, achieved by large-scale production automation and many years of experience in the manufacture of this kind of component. 2 Typical applications for inductors and chokes Inductance low high ∗ ∗ ∗ ∗ Current rating low high low high ∗ low Resonance frequency very high high high medium medium high Q factor very high low high high * — DC resistance low very low low low low medium

Application RF circuits, resonant circuits EMC RFID DC/DC converters Transformers in DC/DC Signal processing

∗ depends on the specific application 2.1 RF circuits

The SIMID product range and leaded RF chokes are especially suitable for RF and other highfrequency circuits. Typical applications are resonant circuits and frequency-selective filters of the type increasingly used in telecommunications engineering and automotive electronics. EPCOS also offers double-aperture transformers for use as directional couplers and splitters. 2.2 Filter circuits

When inductive components are used for filters in power supplies for electronics, high inductance, the lowest possible DC resistance and a low Q factor are required. The impedance should have a wideband frequency characteristic. In addition to the current rating, the maximum permissible pulse current (switching transient currents) and adequately high core material saturation are of importance. Chokes of all type series presented here can be used for this range of applications, from the SIMID types right up to chokes with powder cores and one or two lines.

Please read Important notes and Cautions and warnings.

2

10/08

General technical information

2.3

RFID systems

RFID systems allow contactless identification without direct line-of-sight contact. They are used for wireless data transmission in a range of a few meters. Examples of their application include the automobile industry, logistics, agriculture, medical engineering and security systems. The range of EPCOS transponder coils is especially designed for high mechanical stability and high sensitivity as required in the automobile industry for immobilizers, car access systems and tire pressure monitoring systems (TPMS). 2.4 Switch-mode power supplies, DC/DC converters

Inductive components are used for magnetic energy storage in all kinds of switch-mode power supplies and DC/DC converters. Depending on application, a broad range of different components starting from high-current SIMID and SMT power inductors up to toroid chokes and transformers can be used. Overview Application Step-down converters Typical circuit diagram Components ■ Ring core chokes with iron

powder core
■ SMT power inductors ■ HPI 13, ERU 25...
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