1812J1000682MCTE03 Syfer, 1812J1000682MCTE03 Datasheet - Page 4

• Manufacturer Part Number: 1812J1000682MCTE03
• Description: EMI Filters 1812 .0068uF 100V C0G 20% X2Y Filter
• Manufacturer: Syfer

Specifications of 1812J1000682MCTE03

• Product Category: EMI Filters
• Rohs: yes

6
Electrical configuration
A number of different electrical configurations are available
in feedthrough filters, including the common types shown
opposite. A single element filter (a capacitor or an inductor)
theoretically provides an insertion loss characteristic of 20dB
per decade, a dual element filter (capacitor/inductor) 40dB
per decade whilst a triple element filter (Pi or T configuration)
theoretically yields 60dB per decade. In practise, the insertion
loss curves do not exactly match the predictions, and the data
sheets should be consulted for the realistic figure. The choice
of electrical configuration is made primarily on the source and
load impedances and may also be influenced by the level of
attenuation required at various frequencies.
C filter
This is a feedthrough capacitor with low self inductance. It
shunts high frequency noise to ground and is suitable for use
with a high impedance source and load.
L-C filter
This is a feedthrough filter with an inductive element in
combination with a capacitor. It is commonly used in a circuit
with a low impedance source and a high impedance load
(or vice versa). The inductive element should face the low
impedance.
Source and load impedances
Insertion loss figures are normally published for a 50W source and 50W load circuit. In practise the impedance values will probably
be very different, which could result in either an increase or decrease in insertion loss. The electrical configuration of the filter (the
capacitor/inductor combination) should be chosen to optimise the filter performance for that particular source/load impedance
situation. An estimate of insertion loss for source and load impedances other than 50W can be supplied. Please contact our Sales
Office.
Load current
For filters which include ferrite inductors, the insertion loss under load current may be less than that with no load. This is because
the ferrite material saturates with current. The reduction in insertion loss depends on the current and the characteristics of the
particular ferrite material. In extreme cases the ferrite will become ineffective and insertion loss will appear to be the same as for
a C filter. For further information contact the Sales Office.
Attenuation curve
A plot of insertion
loss versus frequency
on a logarithmic
scale.
Factors affecting insertion loss
The insertion loss performance is used to aid filter
selection by showing signal attenuation at any
given frequency. However, it can only ever be a
guide as actual performance in service will vary
depending on the overall circuit characteristics.
-10
-20
-30
-40
-50
-60
-70
-80
0
0.3
1
10
Frequency (MHz)
Insertion loss is determined by:
l
l
l
l
affected by applied voltage, temperature and the age of the part
l
l
Pi filter
This is a feedthrough filter with 2 capacitors and an inductive
element between them. Ideally, it should be used where both
source and load impedances are high.
T filter
This is a feedthrough filter with 2 series inductive elements
separated by one feedthrough capacitor. It is suitable for use
where both source and load impedances are low.
Electrical configuration
Source/load impedances
The load current (which can cause ferrite saturation)
Ceramic dielectric materials. The capacitance change will be
Earthing impedance
Shielding integrity
100
C
Pi
THREAD
1000
L-C
3000
T
THREAD
C-L
When choosing a filter, it is important to be aware of the different performance characteristics that may be available from
different categories of ceramic materials employed in their capacitors. Generally, stability of dielectric constant (and therefore
filter capacitance value), with respect to some operational and environmental parameters, deteriorates with increasing dielectric
constant. Specific factors which affect dielectric constant are temperature, voltage, frequency and time (ageing).
The three main classifications of ceramic dielectric employed in the manufacture of EMI filters are generally referred to as ultra
stable (C0G/NP0), stable (X7R) and general purpose (Z5U, Y5V or X7W).
C0G/NP0
Most parameters for materials in this dielectric classification
remain unaffected by temperature, voltage, frequency or
time. Stabilities are measured in terms of parts per million but
dielectric constants are relatively low (10 to 100).
X7R
This is a classification for materials which are relatively stable
with respect to temperature, voltage, frequency and time.
Typical dielectric constants would be of the order 2,000 to
4,000, enabling the achievement of far higher capacitance
values for a given size of capacitor than can be gained from
C0G/NP0 materials.
Summary of ceramic dielectric characteristics
Spread of capacitance values
The capacitance of a ceramic capacitor can change as a result of a change in temperature, applied voltage and age. Please note
that this potential change can lead to a significant drop in filtering performance.
Example
Consider the typical
performance of 5,000pF
filter capacitors, offered
in standard dielectric
classifications, operating
at a voltage of 100Vdc at
85°C, at an age of 10,000
hours. The final capacitance
value can fall within the
range of values (see chart
to the right), taking into
account the ageing process
and effects of temperature
and voltage as shown in the
chart above.
It is clear that the capacitance can change as a result of an increase (or decrease) in temperature, applied voltage and as a result
of ageing. If the capacitance has reduced, so too will the insertion loss performance.
EIA dielectric classification
Rated temperature range
Maximum capacitance
change over temperature
range (no voltage applied)
Ageing characteristics
-55ºC to +125ºC
0 ±30 ppm/°C
C0G/NP0
9000pF
8000pF
7000pF
6000pF
5000pF
4000pF
3000pF
2000pF
1000pF
Ultra stable
Zero
0pF
C0G/NP0
negligible
change
Syfer only uses
-55ºC to +125ºC
these two
dielectrics
1% per time
decade
±15%
Stable
X7R
5750pF
3500pF
X7R
to
Choice of ceramic dielectric material
If the voltage coefficient (VC) is critical, Syfer are also able
to offer parts with BX (2X1) and BZ (2C1) VC characteristics.
Refer to the factory for further details.
Z5U/Y5V/X7W
These are classifications for materials which are relatively
unstable with respect to temperature, voltage, frequency and
time. Whilst typical dielectric constants may be of the order
5,000 to 25,000, operating temperature ranges are severely
restricted.
A summary of the specifications of these materials follows.
Please note that Syfer uses only the higher performance C0G/
NP0 and X7R in its standard ranges.
6% per time
6100pF
1000pF
Z5U
+22-56%
-10ºC to
+85ºC
decade
to
Z5U
6100pF
Y5V
500pF
to
General purpose
6% per time
+22-56%
-30ºC to
decade
+85ºC
Y5V
X7W
8540pF
250pF
to
Nominal
6% per time
+40-90%
-55ºC to
+125ºC
decade
X7W
7