High Speed Transmission Equipment
ISDN U-Interface
F1250T
ISDN S/T Interface
F1250T
Tip
RX
P0640SC MC
TX
ISDN
Transceiver
ISDN
Transceiver
P2600SC MC
F1250T
Ring
RX
P0640SC MC
TX
Power
Sink
Power
Source
Figure 3.12 ISDN Protection
Component Selection
The “SC MC” SIDACtor devices and F1250T TeleLink fuse were chosen because these
components meet GR 1089 surge immunity requirements without the use of additional
series resistance. An MC is chosen to reduce degradation of data rates. The P2600SC MC
voltage rating was selected to ensure coordination with MLT voltages that can approach
150 V rms. The voltage rating of the P0640SC MC was selected to ensure coordination with
varying signal voltages.
Pair Gain Circuit Protection
A digital pair gain system differs from an ISDN circuit in that ring detection, ring trip, ring
forward, and off-hook detection are carried within the 64 kbps bit stream for each channel
rather than using a separate D channel. The pair gain system also uses loop powering from
10 V up to 145 V with a typical maximum current of 75 mA. (Figure 3.13)
Remote Terminal (RT)
building or pedestal
mounted
Customer
Premises
(CP)
Central Office (CO)
Remote
Terminal
MDF
Central Office
Terminal (COT)
Switching
System
VF
1
HF
VF
2
VF
1
POTS
POTS
Line 1
Line 2
HF
VF
2
Line powered
DSL 2-Wire,
160 kbps
2B1Q
Figure 3.13 Pair Gain Overview
© 2002 Teccor Electronics
3 - 11
http://www.teccor.com
+1 972-580-7777
®
SIDACtor Data Book and Design Guide
TECCOR [ TECCOR ELECTRONICS ]
