PBL 386 11/2
DC characteristics
C
C
B
B
A
D
D
E
J
G
F
H
F
VTR [V]
500
RLC
A:
IL (@ VTR = 0) = ILConst
ILConst (typ) = ILProg =
(14)
B, C: IL = ILConst VTR = VBatVirt - RFeed • (ILProg - 5•10-3)
RSG
400
D:
RFeed
=
+ 40
E:
F:
G:
H:
J:
IL ≈ 5 mA
Apparent battery VApp (@IL = 0) = VBatVirt + 5•10-3 • RFeed
RFeedG = 2 • 25 Ω
VTRMax = |VBat| - VBOH
Virtual battery VBatVirt (@ IL = 5 mA) = |VBat| - 6.1(17)
Figure 14. Battery feed characteristics (without the protection resistors on the line).
Active State
Active Polarity Reversal State
Overvoltage Protection
TIPX is the terminal closest to ground and TIPX and RINGX polarity is reversed com- PBL 386 11/2 must be protected against
sources loop current while RINGX is the pared to the Active State: RINGX is the overvoltages on the telephone line. The
more negative terminal and sinks loop cur- terminal closest to ground and sources overvoltages could be caused for instance
rent. The loop current or the ground key loop current while TIPX is the more nega- by lightning, ac power contact and induc-
detector is activated. The loop current de- tive terminal and sinks current. The loop tion. Refer to Maximum Ratings, TIPX and
tector indicates off hook with a logic low current or the ground key detector is acti- RINGX terminals, for maximum continu-
level and the ground key detector indicates vated. The loop current detector will indi- ous and transient voltages.
active ground key with a logic high level cate off hook with a logic low level and the
present at the detector output.
ground key detector will indicate active
groundkeywithalogichighlevelpresentat
the detector output.
16
ERICSSON [ ERICSSON ]
