Datasheet

73M1866B/73M1966B Data Sheet DS_1x66B_001
68 Rev. 1.6
10.5 Trans-Hybrid Cancellation
In order to improve performance, the Trans-hybrid Cancellation option allows a replica of the transmit
signal to be created within the 73M1x66B and fed back to the RXM pin via an external circuit at the line
interface. With a well matched AC impedance the amount of cancellation achieved is >26 dB. This
function can be enabled or disabled.
RXM
RXP
TXM
Tx Buf
Vin
-
Vin+
Rp
Rn
52.3 kΩ
17.4 kΩ
21 kΩ
4.7 uF
+
-
Rx Buf
From the Line
Figure 38: Trans-hybrid Cancellation
10.6 Direct Access Arrangement Control Functions
These Transmit Control Registers contain control information to set up the line side of the 73M1x66B.
Included are DC-IV characteristics, off-hook control, etc.
Table 38: DAA Control Functions
Function
Mnemonic
Register
Location
Type Description
ACZ 0x16[3:0] W Active Termination Loop
Controls the selection of the active termination loops per the table
shown below. ATEN must be set to 1 for selection to be enabled.
ACZ Field Active Termination Loop Setting
0000
600 Ω
0001
900 Ω
0010
270 Ω + 750 Ω || 150 nF and 275 Ω +
780 Ω || 150 nF (ETSI ES 203 021-2)
0011
220 Ω + 820 Ω || 120 nF and 220 Ω +
820 Ω || 115 nF (Australia)
0100
370 Ω + 620 Ω || 310 nF
0101
320 Ω + 1050 Ω || 230 nF
0110
370 Ω + 820 Ω || 110 nF
0111
275 Ω + 780 Ω || 115 nF
1000
120 Ω + 820 Ω || 110 nF
1001
350 Ω + 1000 Ω || 210 nF
1010
200 Ω + 680 Ω || 100 nF (China)
1011
600 Ω + 2.16 µF
1100
900 Ω + 1 µF
1101
900 Ω + 2.16 µF
1110
220 Ω + 400 Ω || 70 nF (China)
1111
270 Ω + 600 Ω || 150 nF (Global
Impedance)