Civil Engineering Reference
In-Depth Information
Noise Immunity against Transients—Direct Capacitive Impulse Coupling
The direct capacitive impulse coupling method is similar to the noise immission
method into signal and data lines using a capacitive coupling calliper corresponding
to ISO 7637 Part 3 or IEC 61000-4-4, respectively, which is applied for immunity
measurement of electronic components. In this case, though the 100-pF distributed
capacity of the standardized coupling calliper is substituted by a discrete capacity in
the form of a capacitor component in order to perform the noise immunity measure-
ments while using test boards.
Based on this approach, the measurement process is very similar to the DPI
method and to the 150-Ω method. Therefore, this approach can be applied in com-
bination with the latter methods for the evaluation of CAN transceivers with respect
to radiated and impulse-based noise.
ESD Measurement
For ESD tests, the test directive specifies an analysis of the destruction immunity of
CAN transceivers. For this purpose, an ESD is required, using the “human body”
model (HBM) corresponding to IEC 61000-4-2 (R = 330 Ω, C = 150 pF and tan ca.
700 ps) and applied onto the global pins of the CAN transceiver with no power sup-
ply. This test is oriented towards the requirements of the so-called packaging and
handling tests as known from automotive industries, which requires the ESD with
this network to the connector pins of the component.
2.4.3.3
Basic Test Procedure for EMC Evaluation of CAN
Basic Thoughts
The basic approach to an EMC evaluation of CAN transceivers shall result in a test
close to application while using IC measurement methods which are oriented on the
test constraints and requirements for the higher level measurements of components
and vehicles. For this purpose, the transceiver basically is tested by connecting to
a minimum circuitry as specified by the semiconductor supplier (e.g. stabilizing
capacitors at the supply pins or filter circuit at wake pin).
Another approach though is applied concerning the CAN bus lines circuitry: In
this case, the specification of the applicant (car manufacturer) is applied, who only
specifies a specific CMC as bus filter. In order to comply with this influence, the
following commitment was made:
• Test without bus filter which results in high dynamics measurement for the com-
parison of different types of transceivers.
• Test with bus filter (CMC for noise suppression) for the adaptation to the real
application constraints, if they have been implemented EMC optimal.
• Corresponding to the single-test requirements at first a grouping into two main
test parts is done:
