Datasheet

DS_1x66B_001 73M1866B/73M1966B Data Sheet
Rev. 1.6 67
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5
0
1
2
3
4
5
6
7
8
9
10
Freq Response of IPMF, AZ=01
kHz
10
0
F1db f 1000⋅( )
50 f
Figure 36: Magnitude Response of Impedance Matching Filter, ACZ (3:0)=0010 (ES 203 021-2)
10.4 Billing Tone Rejection
Some countries use a large amplitude out-of-band tone to measure call duration and to allow remote
central offices to determine the duration of a call for billing purposes. To avoid saturation and distortion of
the input caused by these tones, it is important to be able to reject them. These frequencies are typically
12 kHz or 16 kHz.
The 73M1x66B has an integrated notch filter that attenuates either of these tones. By enabling this filter
and selecting the position of the notch frequency, such tones will be attenuated.
Figure 37 shows the magnitude response of the filter with a notch at either 12 kHz (F1) or 16 kHz (F2).
0 2 4 6 8 10 12 14 16 18 20
50
40
30
20
10
0
10
Spans 20kHz
10
50−
F1db f 1000⋅( )
F2db f 1000⋅( )
200 f
Figure 37: Magnitude Response of Billing Tone Notch Filter
In addition to the notch filter, the 73M1x66B can indicate the presence of an overload condition when a
line’s AC voltage exceeds 3.5 Vpk.