turck IM1-12-R Handbuch Seite 27

Anhang – EXIDA-Report FMEDA Turck 04/07-14 R002
The block diagrams above show the working principal of all considered versions with the
exception that the presented block diagrams have two input and two output channels. The
differences between the versions are described in Table 1.
The Isolating Switching Amplifiers IM1-**(Ex)-* and MK13-R-Ex0 are considered to be Type A
components with a hardware fault tolerance of 0.
Although the Isolating Switching Amplifiers IM1-**(Ex)-* and MK13-R-Ex0 are designed with a
semi-custom ASIC 724 from ZETEX (see [D23]) they are still considered to be Type A
components. The reason is the low complexity, the full analyzability of the used ASIC and the
fact that the ASIC does not contain hidden state information such as internal digital registers
(see [D24]). It only consists of 103 transistors, 908 resistors and 7 junction capacitors, which
can individually be connected (see [D25]).
exida.com did a detailed analysis of the ASIC based on the individual failure modes of the
internal transistors, resistors and capacitors (see [R4] to [R11]). Possible dependencies were
taken into account with a common cause factor of 25%. The failure rate from the Siemens
standard SN 29500 for a bipolar ECL ASIC with 50 to 5000 transistors was multiplied with a
safety factor of 2. The resulting 100 FIT were used in the overall analysis for the Isolating
Switching Amplifiers IM1-**(Ex)-* and MK13-R-Ex0.
© exida.com GmbH TURCK 04-07-14 R002 V3R0.doc; February 21, 2014
Stephan Aschenbrenner Page 9 of 25
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