6.5.3. Circuits GND, GND* and AGND
Connecting external circuits of module
E20-10
shall be performed based on its internal connecting
diagram for common wires from different connectors –
Fig. 6-4. Circuits GND, GND* and AGND
Module
E20-10
has no internal galvanic separations, hence, GND, GND* and AGND
circuits have internal coupling (p.
): common wire of digital circuits GND in one point inside
E20-10
is connected to common wire of analog circuits AGND.
External power source common
wire
is connected to the same
internal point
E20-10 via in-phase EMC filter.
On principle, that common wire of USB interface from computer (connected to computer
case) is connected to common wires connection point inside of
E20-10.
When connecting
E20-10
to external circuits you should remember, that the most proper
connecting of
E20-10
is that connecting which would not result in through currents passage via
circuits:
GND—AGND, GND—computer case or AGND—GND—computer case.
Attention!
Presence of abovementioned through currents can degrade signal-noise rate in
E20-10
channels, cause unsteady operation of USB or USB-hub, and when exceeding of maximum
permissible through currents(
table 6-5
)
E20-10
and connected equipment failure.
If such currents are unavoidable on any case in your system it is required to take measures to
minimisation them (pp.
General recommendation on instruments connecting are given in special article [2].
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20
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AGND
AGND
AGND
AGND
AGND
GND
GND
GND*
Внутренняя
точка
соединения
ANALOG
USB
1
2
3
4
DIGITAL I
/O
Фильтр
Filter
Internal
connection point