Circuits Gnd, Gnd* And Agnd; Fig. 6-4. Circuits Gnd, Gnd* And Agnd - L-Card E20-10 User Manual

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 –
Module E20-10 has no internal galvanic separations, hence, GND, GND* and AGND
circuits have internal coupling (p. 6.5.3): 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
If such currents are unavoidable on any case in your system it is required to take measures to
minimisation them (pp.6.5.4.5, 6.5.4.6).
General recommendation on instruments connecting are given in special article [2].
1
2
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9 8 7
6 5 4 3
2 1

Fig. 6-4. Circuits GND, GND* and AGND

currents(table 6-5) E20-10 and connected equipment failure.
Fig. 6-4.
USB
GND
Внутренняя
Internal
точка
connection point
соединения
Фильтр
Filter
GND*
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3
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27
9
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32
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