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Inductive components for electronic equipment

Especially in this age of fully-electronic and highly-integrated equipment, inductive components are

indispensable. They are used to store energy intermittently in switch-mode power supplies and

DC/DC converters, as parts of high-frequency circuits, as filter elements and last but not least as

interference suppression components to ensure EMC.

Of course, the demands placed on inductors depend on how and where they are to be used. In HF

circuits, coils with high quality factors and resonance frequencies are needed. In EMC applications,

high inductances are required in order to achieve good interference suppression characteristics, low

Q factors being more desirable here due to the need to avoid resonances.

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) right up to the 4-line

high-current inductors for power electronics applications.

Attention is drawn to the excellent HF characteristics and the extremely high reliability of the com-

ponents, achieved thanks to large-scale production automation and many years of experience in

the manufacture of this kind of components.

An overview of typical applications for inductors and chokes

1.1

HF circuits

SMT styles (SIMID product range) and leaded RF chokes are especially suitable for RF and other

high-frequency circuits. Typical applications are resonant circuits and frequency-selective filters of

the type being increasingly used in telecommunications engineering and automotive electronics. In

some cases, special demands on the inductive components arise, for example, when used in trans-

mitter output circuits of mobile telephones (high

Q factors and resonance frequencies) and in air-

bag control circuits (high pulse currents).

1.2

Filter circuits

When inductive components are used for filters in power supplies for electronics, high inductances, the

lowest possible DC resistance and a low

Q factor are required. The impedance should have a wide-

band 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 belonging to 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.

Application

Inductance

Current rating Resonance

frequency

Q factor

DC resistance

HF circuits,

resonant circuits

low

low

very high

very high

low

EMC

high

∗

high

low

very low

Filter circuits

high

high

high

low

very low

Switch-mode

power supplies,

DC/DC converters

∗∗

medium

high

low

∗ depends on the specific application

General Technical Information

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