L3000N - L3092
Limiting Current
60mA
40mA
25mA
GDK = 0
(0 – 300) ohm
(0 – 650) ohm
(0 – 1300) ohm
GDK = 1
>300 ohm
>650 ohm
>1300 ohm
If, for example, the loop resistance is 400Ω the
GDK output will be 0 only when the limiting current
value is 40 or 25mA.
The card controller can program consecutive Test
Mode and Conversation Mode with different limiting
current in order to individuate the range of loop re-
sistance as shown in the flow chart of fig. 6.
The information of the Loop Resistance Range
can be very useful to optimize the transmission
characteristics of the Line Card to each line.
For example, if a second generation COMBO like
TS5070 is used the Card Controller can use this
information to change the Tx, RX Gains and echo
cancellation characteristics into the programma-
ble COMBO improving the quality of the system.
Figure 6: Procedure for Loop Resistance Evaluation.
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