Customer Premises Equipment (CPE)
Customer Premises Equipment (CPE)
CPE is defined as any telephone terminal equipment which resides at the customer’s site
and is connected to the Public Switched Telephone Network (PSTN). Telephones, modems,
caller ID adjunct boxes, PBXs, and answering machines are all considered CPE.
Protection Requirements
CPE should be protected against overvoltages that can exceed 800 V and against surge
currents up to 100 A. In Figure 3.1 through Figure 3.6, SIDACtor devices were chosen
because their associated peak pulse current (IPP) rating is sufficient to withstand the
lightning immunity test of TIA-968 (formerly known as FCC Part 68) without the additional
use of series line impedance. Likewise, the fuse shown in Figure 3.1 through Figure 3.6
was chosen because the amps2time (I2t) rating is sufficient to withstand the lightning
immunity tests of TIA-968 without opening, but low enough to pass UL power cross
conditions.
The following regulatory requirements apply:
•
•
TIA-968 (formerly known as FCC Part 68)
UL 60950
All CPE intended for connection to the PSTN must be registered in compliance with
TIA-968. Also, because the National Electric Code mandates that equipment intended for
connection to the telephone network be listed for that purpose, consideration should be
given to certifying equipment with an approved safety lab such as Underwriters
Laboratories.
CPE Reference Circuits
Figure 3.1 through Figure 3.6 show examples of interface circuits which meet all applicable
regulatory requirements for CPE. The P3100SB and P3100EB are used in these circuits
because the peak off-state voltage (VDRM) is greater than the potential of a Type B ringer
superimposed on a POTS (plain old telephone service) battery.
150 VRMSꢀꢁ2 + 56.6 VPK = 268.8 VPK
Note that the circuits shown in Figure 3.1 through Figure 3.6 provide an operational solution
for TIA-968 (formerly known as FCC Part 68). However TIA-968 allows CPE designs to
pass non-operationally as well.
For a non-operational solution, coordinate the IPP rating of the SIDACtor device and the I2t
rating of the fuse so that (1) both will withstand the Type B surge, and (2) during the Type A
surge, the fuse will open. (See Table 5.1, Surge Rating Correlation to Fuse Rating on page
5-8.)
Note: For alternative line interface protection circuits, see "Regulatory Compliant Solutions"
on page 4-34.
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SIDACtor Data Book and Design Guide
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