Hi All,
Not sure if this is the right post to ask this question but
feedback would be appreciated.
Can anyone provide me with the difference between a bypass and decoupling
capacitor? My understanding is that bypass caps are used for stabilizing a
power supply, and would be used to provide low end AC filtering on a power
supply up to a couple hundred MHz and they could be located from the power
supply output to being scattered through a board to stabilize the power
distribution system and normally have higher than .1uF cap values. Also,
decoupling caps would be used local to the ICs on the PCB and provide high
frequency noise coupling as well as provide some local power stabilization for
the switching noise that will occur due to the high frequency switching of the
transistors in the IC.
When I looked online for these definitions, it seems like some
people are using these terms interchangeably. It may just be semantics, but I
am looking for some confirmations from people with a bit more experience on
this subject.
Thanks in advance for your help.
Paul Denomme
From: [email protected] [mailto:[email protected]] On Behalf Of John McAuley
Sent: Thursday, March 13, 2008 12:21 PM
To: 'Leber Jody-G19980'; [email protected]
Subject: RE: Cigarette Light Adapter Requirements
Jody
Europe - The following was copied from the Automotive EMC Directive
2004/104/EC. I am not aware of any electrical safety requirements. The voltage
will be less than that specified by the LVD?
Basically you have radiated emissions, emissions of conducted transients and
transient immunity to ISO 7637 standards.
In the light of the experience gained since the
amendment to Directive 72/245/EEC, it is no longer
necessary for after-market equipment unrelated to safety
functions to be regulated by a Directive specifically
concerning electromagnetic compatibility (EMC) in the
automobile sector. For such equipment it is sufficient
to obtain a Declaration of Conformity in accordance
with the procedures laid down in Council Directive89/336/EEC of 3 May 1989 on
the approximation of the
laws of the Member States relating to electromagnetic
compatibility (3) and in Directive 1999/5/EC of the
European Parliament and of the Council of 9 March
1999 on radio equipment and telecommunications
terminal equipment and the mutual recognition of their
conformity (4).
Components sold as aftermarket equipment and intended for the installation in
motor vehicles need no typeapproval
if they are not related to immunity-related functions (Annex I, 2.1.12). In
this case a Declaration of
Conformity according to the procedures of Directive 89/336/EEC or 1999/5/EC
must be issued. Part of this
declaration must be that the ESA fulfils the limits defined in paragraphs 6.5,
6.6, 6.8 and 6.9 of Annex I to this
Directive.
6.5. Specification concerning broadband electromagnetic interference generated
by ESAs
6.5.1. Method of measurement
The electromagnetic radiation generated by the ESA representative of its type
shall be measured by the method
described in Annex VII.
6.5.2. ESA broadband type-approval limits
6.5.2.1. If measurements are made using the method described in Annex VII, the
limits shall be 62 to 52 dB microvolts/
m in the 30 to 75 MHz frequency band, this limit decreasing logarithmically
with frequencies above 30
MHz, and 52 to 63 dB microvolts/m in the 75 to 400 MHz band, this limit
increasing logarithmically with
frequencies above 75 MHz as shown in Appendix 6 to this Annex. In the 400 to 1
000 MHz frequency band
the limit remains constant at 63 dB microvolts/m.
6.5.2.2. On the ESA representative of its type, the measured values, expressed
in dB microvolts/m, shall be below the
type-approval limits.
6.6. Specifications concerning narrowband electromagnetic interference
generated by ESAs.
6.6.1. Method of measurement
The electromagnetic radiation generated by the ESA representative of its type
shall be measured by the method
described in Annex VIII.
6.6.2. ESA narrowband type-approval limits
6.6.2.1. If measurements are made using the method described in Annex VIII,
the limits shall be 52 to 42 dB
microvolts/m in the 30 to 75 MHz frequency band, this limit decreasing
logarithmically with frequencies
above 30 MHz, and 42 to 53 dB microvolts/m in the 75 to 400 MHz band, this
limit increasing logarithmically
with frequencies above 75 MHz as shown in Appendix 7 to this Annex. In the 400
to 1 000 MHz frequency
band the limit remains constant at 53 dB microvolts/m.
6.6.2.2. On the ESA representative of its type, the measured value, expressed
in dB microvolts/m shall be below the
type-approval limits
6.8. Specifications concerning the immunity to transient disturbances
conducted along supply lines
6.8.1. Method of testing
The immunity of ESA representative of its type shall be tested by the
method(s) according to ISO
7637-2:DIS2002 as described in Annex X with the test levels given in Table 1.
6.9. Specifications concerning the emission of conducted disturbances
6.9.1. Method of testing
The emission of ESA representative of its type shall be tested by the
method(s) according to ISO
7637-2:DIS2002 as described in Annex X for the levels given in Table 2.
ANNEX X
METHOD(S) OF TESTING FOR IMMUNITY TO AND EMISSION OF TRANSIENTS OF
ELECTRICAL/ELECTRONIC
SUBASSEMBLIES
1. General
This test method shall ensure the immunity of ESAs to conducted transients on
the vehicle power supply and limit
conducted transients from ESAs to the vehicle power supply.
2. Immunity against disturbances conducted along supply lines
Apply the test pulses 1, 2a, 2b, 3a, 3b and 4 according to the International
Standard ISO 7637-2:2002 to the supply
lines as well as to other connections of ESAs which may be operationally
connected to supply lines.
3. Emission of conducted disturbances along supply lines
Measurement according to the International Standard ISO 7637-2:2002 on supply
lines as well as to other
connections of ESAs which may be operationally connected to supply lines.
John McAuley
Compliance Engineering Ireland Ltd
<http://www.cei.ie> www.cei.ie
<mailto:[email protected]> [email protected]
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From: [email protected] [mailto:[email protected]] On Behalf Of Leber
Jody-G19980
Sent: 13 March 2008 14:29
To: [email protected]
Subject: Cigarette Light Adapter Requirements
Is anyone aware of the current enforced or obligatory Safety/EMC/Other
requirements that are being applied to Cigarette Lighter Adapters?
I am am aware of the following:
US: UL 2089, Not mandatory
EU: CE Mark (not e-Mark)?
EMC: Appropriate Standards?
Safety: Any Requirements?
Any other countries?
Best Regards,
Jody Leber
Program Manager
[email protected]
http://www.motorola.com/producttesting
blocked::http://www.motorola.com/producttesting>
Motorola Product Testing Services
1700 Belle Meade Court
Lawrenceville, GA 30043
770.338.3581 P
404.387.1224 C
847.761.3145 F
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