Download TR41.1.1-05-08-010-Infineon-Ring

Telecommunications Industry Association
TR41.1.1/05-08-010
Document Cover Sheet
Project Number
SP-3-0191: Standard for a Packet-based VoIP Terminal Adapter Analog
Telephone Port
Document Title
Ringing Voltage for VoIP Terminal Adapters
Source
Infineon Technologies
Contact
Distribution
Intended Purpose
of Document
(Select one)
Michael Pirker
Infineon Technologies
1730 North First Street
San Jose, CA 95112
U.S.A.
Phone: (408) 501-6713
Fax: (408) 501-2486
Email: [email protected]
TR-41.1.1
x
For Incorporation Into TIA Publication
For Information
Other (describe) -
The document to which this cover statement is attached is submitted to a Formulating Group or
sub-element thereof of the Telecommunications Industry Association (TIA) in accordance with the
provisions of Sections 6.4.1–6.4.6 inclusive of the TIA Engineering Manual dated March 2005, all of
which provisions are hereby incorporated by reference.
Abstract
We would like to point out some drawbacks of the inclusion of a 15-Vdc offset for Ringing Voltage.
Telecommunications Industry Association
TR41.1.1/05-08-010
“55 Vrms super-imposed on 15 Vdc”
The meeting notes, TR41.1.1/05-08-002, state:
“It was finally agreed not to change the existing ringing voltage requirement in the draft 4 standard (i.e. 40 Vrms
“shall” and 55 Vrms “should”) but to add requirement that ringing should be superimposed on minimum 15 Vdc.”
Accordingly, the new draft, TR41.1.1/05-08-005-R1, states:
5.1.4.1
The analog telephone port shall provide a ringing signal between the tip and ring conductors that meets
the following characteristics:
(1)
…
(2)
…
(3)
…
(4)
…
(5)
The magnitude of the ringing signal ac component into a load of 5 REN applied at the analog
telephone port shall be greater than 40 V rms and should be greater than 55 V rms when superimposed
on minimum 15 Vdc. For testing purposes, the impedance of a load of REN n should be a resistor of
(6930/n) ohms in series with a capacitance of (8*n) µF;
(6)
…
Our first concern was, Was this actually agreed in the discussion? We don’t recall this being the case.
Also, this requirement has not appeared in previous relevant specifications: T1.401-2000, GR-57, or GR-909.
Reduction of Ringing Amplitude
Another concern is that mandating a DC offset will reduce the available ringing voltage for a given battery supply,
because the SLIC can only provide a maximum voltage span, which will have to provide both the DC and the AC
voltage. A mandate of 15 Vdc results in a reduction of about 10.8 Vrms in the available ringing voltage.
Increase in Power Dissipation
A 15 Vdc offset will contribute very significantly to power consumption by the SLIC.
For example, ringing into 5 REN with 55 Vrms requires 39 mArms. With a 15Vdc offset, this will lead to additional
power consumption of more than half a Watt. (15V * 39mA * 0.9 = 526.5 mW)
Proposal
For these reasons, we suggest that it may be appropriate to designate the 15 Vdc offset as a “desirable” rather than a
mandatory feature.
Page 2