G
[email protected]
- Jan 1, 1970
- 0
Hi,
I'm working on a design which is supplied from an external DC power
source. I'm routing the supply (+ and -)via a common mode choke, so
there's conceptually a separate DC ground either side of the choke (at
least from a CM a.c. perspective).
The board also has a few RS232 ports and digital I/O lines, (each of
which is fed through 3 terminal capacitors). These 'external' IO lines
are presented on a connector.
My feeling is that any DC ground that I should make available on the
external connector should be taken from *before* the common mode
choke, since if it was the 'filtered' DC ground that was made
available externally, the filter itself would get shunted if
'external' grounds were commoned.
_________
DC in + | | DC in + (Filtered)
----- | CM |-----
DC in - |Choke | DC in - (Filtered)
----- | |-----
| _________
|
|
_| Ground connection to ext.connector
I'm curious to know what the perceived wisdom is in this case? - Does
this sound reasonable?
Many thanks
David
I'm working on a design which is supplied from an external DC power
source. I'm routing the supply (+ and -)via a common mode choke, so
there's conceptually a separate DC ground either side of the choke (at
least from a CM a.c. perspective).
The board also has a few RS232 ports and digital I/O lines, (each of
which is fed through 3 terminal capacitors). These 'external' IO lines
are presented on a connector.
My feeling is that any DC ground that I should make available on the
external connector should be taken from *before* the common mode
choke, since if it was the 'filtered' DC ground that was made
available externally, the filter itself would get shunted if
'external' grounds were commoned.
_________
DC in + | | DC in + (Filtered)
----- | CM |-----
DC in - |Choke | DC in - (Filtered)
----- | |-----
| _________
|
|
_| Ground connection to ext.connector
I'm curious to know what the perceived wisdom is in this case? - Does
this sound reasonable?
Many thanks
David