PCT1789W DATA SHEET
PRELIMINARY
APPENDIX: NET4 COUNTRY SUPPORT
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APPENDIX: NET4 COUNTRY SUPPORT
Introduction
Ringer Impedance
The PCT303DW has a very high impedance ring
detector that satisfies the requirements of most
countries. In order to meet the maximum impedances of
Germany (20 kW) and South Africa (60 kW), while not
violating the minimum 20 kW requirement of Austria, a
selectable ringer impedance has been included. The
default (mode 0) is 24 kW and satisfies most countries.
Mode 1 selects a 16 kW impedance, primarily to support
Germany. The mode is selected by the RZ bit of
register 16.
The international design for the PCT303DW can be
implemented to support global requirements targeting
compliance with CTR21 or compliance with NET4. This
appendix outlines the component changes and control
registers required for NET4 support. NET4 support
requires different DC termination (mode 0) and
programmable ringer impedance and ringer threshold in
order to meet country-specific requirements. Some
component changes (vs. CTR21 only support) are
necessary and are outlined in the notes of Table 32 on
page 67.
Ringer Threshold
Mode 0
The PCT303DW has a programmable ringer threshold.
Mode 1 sets a ring threshold of 21.5 ± 5 Vrms. The mode
is selected by bit 0 (RT) of register 16. Most countries
will be programmed as mode 1 except Switzerland,
Austria, and Belgium which require mode 0. Many
countries can operate in either mode, such as those
complying to FCC regulations.
Mode 0 (0,0) is a low-voltage mode which supports a
maximum transmit signal of –5.22 dBm. This mode
meets the very low voltage requirements for countries
such as Norway. See Figure 33.
Mode 0
11
10
9
8
7
6
5
.05 .06
.11
.09 .1
.01
.02 .03 .04
.07 .08
Loop Current (A)
Figure 33 Mode 0 I/V Characteristics (0,0)
PRELIMINARY
PC-TEL, Inc.
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1789W0DOCDAT06A-0299
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