Datasheet

DS_1x66B_001 73M1866B/73M1966B Data Sheet
Rev. 1.6 65
The 73M1x66B can:
• Shift the characteristics by setting the turn-on voltage.
• Enable a current limit of 42 mA.
The 73M1x66B meets a wide range of different countries’ requirements under software control. See
Section 10.7.
There are two operating states for the DC-IV circuits: Hold and Seize.
0
2
4
6
8
10
12
14
5
9
15
20
30
40
50
60
70
80
90
96
110
Tip/Ring Voltage
DC Current, mA
DCVI Performance
DCIV=00
DCIV=01
DCIV=10
DCIV=11
Figure 34: Tip-Ring Voltage versus Current Using Different DCIV Settings
The Hold state is the nominal operational point for the DC-IV circuits. The response shown in Figure 34
is for the Hold state (both DC and AC transconductance circuits are enabled). The slope of the DC-IV
characteristics is approximately 50 Ω when the series resistance of a typical PPTC resettable fuse is
taken into account.
The Seize state is a condition that is used by some central offices to determine an off-hook condition. In
this state an additional load is added to the nominal operational DC-IV characteristics used during the
Hold state
In the Seize state (only the DC transconductance circuit is enabled), the turn-on voltage is reduced on the
line independent of the DCIV control bits. See Figure 35 and the description of the DCIV bits in
Section 10.6.