73M1866B/73M1966B Data Sheet
DS_1x66B_001
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.
Tx Buf
TXM
17.4 kΩ
Vin
Rn
-
-
RXM
21 kΩ
Rx Buf
Rp
From the Line
RXP
+
Vin+
52.3 kΩ
4.7 uF
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 Location
ACZ 0x16[3:0]
Register
Type
Description
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
0000
Active Termination Loop Setting
600 Ω
900 Ω
0001
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
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
370 Ω + 620 Ω || 310 nF
320 Ω + 1050 Ω || 230 nF
370 Ω + 820 Ω || 110 nF
275 Ω + 780 Ω || 115 nF
120 Ω + 820 Ω || 110 nF
350 Ω + 1000 Ω || 210 nF
200 Ω + 680 Ω || 100 nF (China)
600 Ω + 2.16 µF
900 Ω + 1 µF
900 Ω + 2.16 µF
220 Ω + 400 Ω || 70 nF (China)
270 Ω + 600 Ω || 150 nF (Global
Impedance)
68
Rev. 1.6
TERIDIAN [ TERIDIAN SEMICONDUCTOR CORPORATION ]
