Datasheet

 2013-2015 Microchip Technology Inc. DS00001987A-page 49
LAN8740A/LAN8740Ai
The typical cable length measurement margin of error for Open and Shorted cases is dependent on the selected cable
type and the distance of the open/short from the device. Table 3-10 and Table 3-11 detail the typical measurement error
for Open and Shorted cases, respectively.
TABLE 3-10: TYPICAL MEASUREMENT ERROR FOR OPEN CABLE (+/- METERS)
Physical Distance to
Fault
Selected Propagation Constant
P
OPEN
= Unknown P
OPEN
= CAT 6 P
OPEN
= CAT 5E P
OPEN
= CAT 5
CAT 6 Cable,
0-100 m
96
CAT 5E Cable,
0-100 m
5 5
CAT 5 Cable,
0-100 m
13 3
CAT 6 Cable,
101-160 m
14 6
CAT 5E Cable,
101-160 m
8 6
CAT 5 Cable,
101-160 m
20 6
TABLE 3-11: TYPICAL MEASUREMENT ERROR FOR SHORTED CABLE (+/- METERS)
Physical Distance to
Fault
Selected Propagation Constant
P
SHORT
= Unknown
P
SHORT
=
CAT 6
P
SHORT
=
CAT 5E
P
SHORT
=
CAT 5
CAT 6 Cable,
0-100 m
85
CAT 5E Cable,
0-100 m
5 5
CAT 5 Cable,
0-100 m
11 2
CAT 6 Cable,
101-160 m
14 6
CAT 5E Cable,
101-160 m
7 6
CAT 5 Cable,
101-160 m
11 3