1769205x2, 176881212, 176861512

FISM

– Fixed Isolated SMT Module

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Würth Elektronik eiSos GmbH & Co. KG

– Data Sheet Rev. 1.0

©July 2018

24/37

APPLICATION CONSIDERATIONS

Primary side parallel connection

A standard industrial configuration is, that the power modules are supplied by a dc bus voltage. When using multiple

modules connected to a single dc bus voltage the individual module inputs have to be decoupled by LC filters.

The LC filter reduces the likelihood of oscillations due to parasitics of a layout/routing. Therefore, it is not recommended

to connect power modules in parallel on the primary side without an LC filter.

+VIN

-VIN

-VOUT

+VOUT

Module 2

2

1

4

5

L2

C2

+VIN

-VIN

-VOUT

+VOUT

Module 1

2

1

4

5

L1

C1

DC

BUS

+

-

+

-

+

-

Decoupl ing fi lter

Decoupl ing fi lter

As a starting point for the decoupling filters, use the values of the reference filters

– see also “RADIATED AND

CONDUCTED EMISSIONS (WITH EMI INPUT FILTER)

”. The final appropriate filter for the application has then to be

evaluated under operation in the target application by checking e.g. the change of the input ripple voltage.