Datasheet

73M1866B/73M1966B Data Sheet DS_1x66B_001
64 Rev. 1.6
10 Configurable Direct Access Arrangement (DAA)
The 73M1x66B Line-Side Device integrates most of the circuitry to implement a PSTN line interface or
DAA that is capable of being globally compliant with a single bill of materials.
The 73M1x66B supports the following DAA functions:
• Pulse dialing
• On and Off Hook switch control
• Loop current (DC-IV) regulation
• Line impedance matching
• Ring detection
• Tip and Ring voltage polarity reversal detection
• Billing tone rejection
• Trans-hybrid cancellation
The device is able to support Barrier Powered Mode in which the PSTN loop current may be as low as 8 mA.
10.1 Pulse Dialing
The 73M1x66B supports Pulse Dialing. See Section 10.6 for the descriptions of applicable control and
status bits.
10.2 DC Termination
DC Termination or Loop Current (DC-IV) regulation is managed by the 73M1x66B Line-Side Device by
configuring the appropriate registers. No additional components are necessary.
The 73M1x66B provides a DC transconductance circuit that regulates the tip to ring voltage depending on
the DC current supplied by the line. There are four settings that can be used to set the voltage to current
ratio.
Figure 33 shows the DC-IV characteristics of the 73M1x66B with special regions of interest.
Figure 33: DC-IV Characteristics
V
I
41 Ω*
Programmable
Turn-on Voltage
Given by
DCIV Control
Bits
Current Limit Turn-on=42 mA
2.2 kΩ
Current Limit Turned on
* ~50 Ω with 8 Ω fuse resistance
Seize Voltage