AN273
GR-909 T
E S T I N G W I T H T H E
S i 3 2 1 X P
R O
SLIC
®
1. Introduction
This document describes how line fault testing (such as GR-909) may be implemented using the Si321X family of
ProSLIC devices. Demonstration code for each test is available.
2. GR-909 Metallic Loop Tests
The five metallic loop tests described by GR-909 are as follows:
1.
Hazardous Potential Test
Under any condition, the following must be detected
>50 V
RMS
ac voltage from TIP-GND or RING-GND
>135 V dc voltage from TIP-GND or RING-GND
2.
Foreign Voltage Test
Under any condition, the following voltages not generated by the SLIC must be detected
>10 V
RMS
ac from TIP-GND or RING-GND
>6 V dc from TIP-GND or RING-GND
3.
Resistive Faults Test
Detect the following resistive line faults
<150 kΩ TIP-RING, TIP-GND, or RING-GND
4.
Receiver Off-hook Test
Distinguish between resistive fault <150 kΩ and an off-hook receiver
5.
Ringing Equivalency Number Test
Determine the REN (Ringer Equivalency Number) of the terminating receiver is between 0.175 REN and
5 REN. Reject if outside that range.
Each of these tests can be implemented on the Si321x devices. Table 1 enumerates the test cases, the measure-
ment method implemented, and the failing criteria.
Table 1. GR-909 Metallic Loop Tests
GR-909 Test
1
2
3
4
5
Test Description
Hazardous Potential
Foreign Voltage
Resistive Faults
Offhook
REN
Linefeed State
OPEN
OPEN
TIP-OPEN, RING-OPEN
TIP-OPEN
RINGING
Measurement
V
TIP
and V
RING
V
TIP
and V
RING
R
TG
, R
RG
, R
TR
R
TR
PQ2
Failure Criteria
> 50 Vrms ac
> 135 V dc
> 10 Vrms ac
> 6 V dc
>150 kΩ
Detect/No-detect
> 5 REN
Rev. 0.1 2/06
Copyright © 2006 by Silicon Laboratories
AN273
SILABS [ SILICON LABORATORIES ]
