SP505AN Datasheet, PDF (19/30 Pages) Sipex Corporation – Multi-Protocol Serial Transceivers

Another alternative is using conductive-EMI
enhanced connectors that have ferrite cores around
the pins. AMP and other connector manufacturers
also offer specially built conductive-EMI filtered
connectors. The AMPLIMITE^™ Subminiature D-Sub
connectors have a DB-15 through DB-37 connectors
as well as high density connectors that have a
distributed element filter using lossy ferrite core or
a capacitive filter assembled around each pin. These
connectors have right-angle, vertical, or stacked
versions that all have the same PCB footprint as the
regular non-filtered connectors.
Various filter types are available with these connectors.
Once the serial protocol is defined and the operating
frequency known, a filter type can be chosen using
its 3dB point, which can be used as the maximum
frequency. The filter will begin filtering above this
3dB point. One should be careful when using the
capacitive filters as they will affect the overall AC
performance of the driver, specifically driver rise/
fall time. Details of the AMPLIMITE^™ filtered
connectors can be found in AMP's home page
(http://connect.amp.com.), which includes insertion
loss (dB) versus frequency.
8
TxD
7
6
TXCE ₅
1
L1
2
L2
3
L3
4
L4
Figure 31. Common-Mode Choke Circuit with Drivers
AMPLIMITE^™ is a trademark of AMP Inc.
SP505/6/7APN/03
SP505, SP506, SP507 Application Note
19
© Copyright 2000 Sipex Corporation