TM8000 3DK Hardware Developer’s Kit
Application Manual
Creating Your Own Options Board
91
September 2003
© Tait Electronics Ltd
4.1.4
Guidelines for EMC Design
Earthing
and
show the recommended earthing of the internal
options board. The earthing used depends on the type of circuitry on the
internal options board.
Figure 4.6
Internal options board - earthing for low-speed circuits
internal
options
connector
from PSU
from digital
from audio
to audio
radio ground plane
to digital
regulated
PSU
low-speed
digital
circuit
analogue
circuit
(low freq.)
external
options
options
cable
13V8_SW
DGND
470p
470p
25V
25V
470
4.7k
DV
DD
AV
DD
10n
10n
470
4.7k
DV
DD
AV
DD
internal options board
(2 layers with no groundplane)
connector
loom
located as close to
the connector
as possible
digital
device
analogue
device
AGND
digital ground
analogue ground
chassis ground
screws
(earth board
to chassis)
Figure 4.7
Internal options board - earthing for high-speed circuits
regulated
PSU
high-
speed
digital
analogue
circuit
(RF)
external
options
options
cable
13V8_SW
AGND
DGND
470p
470p
25V
25V
470
4.7k
DV
DD
AV
DD
DV
DD
AV
DD
internal options board
(4 or more layers)
connector
loom
located as close to
the connector
as possible
digital
device
analogue
circuit
470
470p
internal
options
connector
from PSU
from digital
from audio
to audio
radio ground plane
to digital
digital ground
analogue ground
chassis ground
screws
(earth board
to chassis)
additional
coaxial
connector
device