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Si3038
54
Rev. 2.01
APPENDIX B—CISPR22 COMPLIANCE
Various countries are expected to adopt the IEC
CISPR22 standard over the next few years. For
example, the European Union (EU) has adopted a
standard entitled EN55022, which is based on the
CISPR22 standard. EN55022 is now part of the EU’s
EMC Directive and compliance is expected to be
required starting in 2003. Adherence to this standard
will be necessary to display the CE mark on designs
intended for sale in the EU. The typical schematic and
global bill of materials (BOM) (see
Figure 19 and
Table 16) contained in this data sheet are designed to
be compliant to the CISPR22 standard.
If smaller inductors are desired, a notch filter may be
used and compliance to CISPR22 still achieved. As
shown in
Figure 35, a series capacitor-resistor in
parallel with L1 and L2 forms the simple notch filter.
Table 27 shows corresponding values used for C24,
C25, C38, C39, L1, L2, R31, and R32.
Figure 35. Notch Filter for CISPR22 Compliance
The direct current resistance (DCR) of the listed
inductors is an important consideration. If the DCR of
the inductors used is less than 3
each, then country
PTT specifications which require 300
or less of dc
resistance at TIP and RING with 20 mA of loop current
can be satisfied with the Japan dc termination mode. If
the DCR of the inductors is at or slightly above 3
, the
low voltage termination mode may need to be used to
satisfy the 300
dc resistance requirement at 20 mA of
loop
current.
In
all
cases,
If compliance to the CISPR22 standard and certain
other country PTT requirements are not desired, then
L1 and L2 may be removed. If these inductors are
removed, C24 and C25 should be increased to 2200 pF,
and C9 should be changed to 22 nF, 250 V. With these
changes, PTT compliance in the following countries will
not be achieved: India (I/Fax-03/03 standard), Taiwan
(ID0001 standard), Chile (Decree No. 220 1981
standard), and Argentina (CNC-St2-44.01 standard).
For questions concerning compliance to CISPR22 or
other relevant standards, contact a Silicon Laboratories
technical representative.
Table 27. Notch Filter Component Values
C24/C25 C38/C39
L1/L2
R31/R32
1000 pF
33 pF,
50 V
150
H, DCR
<3
, I >120 mA
680
,
1/10 W
C38
C24
L1
R31
FB1
TIP
To
DAA
C39
C25
L2
R32
FB2
RING