PBL 386 20/2
RFB
PBL 386 20/2
CTX
RTX
KR
-
PTG
VTX
-
0
+
+
RT
RRLY
HP
AGND
RSN
NC
RB
+12 V /+5V
CHP
RRX
0
CGG
NC
CODEC/
Filter
RF2
RR
RP2
RING
RINGX
BGND
TIPX
VBAT
VBAT2
PSG
NC
REF
PLC
POV
PLD
VCC
NC
RREF
RLC
ROV
RLD
CRC
CTC
VB
OVP
TIP
RF1
RP1
PBL 386 20/2
DVB2
VB2
VB
VCC
VCC
DBB
DVB
RSG
CVB2
CVCC
DET
C1
CLP
ERG
CVB
R1
LP
RRT
PLCC 28-PIN
PACKAGE
DT
C2
R2
DR
C3
C1
C2
SYSTEM CONTROL
INTERFACE
R3
R4
SLIC No. 2 etc.
RESISTORS (Values according to IEC E96 series):
OVP:
CAPACITORS (Values according to IEC E96 series):
Secondary protection (e. g. Power Innovations
TISPPBL2). The ground terminals of the secondary
protection should be connected to the common
ground on the Printed Board Assembly with a track
as short and wide as possible, preferable a
groundplane.
RSG
RLD
ROV
RLC
RREF
RR
= 0 Ω
1% 1/10 W
1% 1/10 W
CVB
= 100 nF
= 150 nF
= 100 nF
= 2.2 nF
= 2.2 nF
= 47 nF
100 V 10%
100 V 10%
10 V 10%
100 V 10%
100 V 10%
100 V 10%
100 V 10%
10 V 10%
100 V 10%
63 V 10%
63 V 10%
= 49.9 kΩ
CVB2
CVCC
CTC
= User programmable
= 38.3 kΩ
= 49.9 kΩ
= 64.9 kΩ
= 105 kΩ
= 24.9 kΩ
= 22.1 kΩ
= 52.3 kΩ
1% 1/10 W
1% 1/10 W
1% 1/10 W
1% 1/10 W
1% 1/10 W
1% 1/10 W
1% 1/10 W
CRC
CHP
RT
CLP
= 150 nF
= 100 nF
= 220 nF
= 330 nF
= 330 nF
RTX
RB
CTX
CGG
C1
RRX
RFB
R1
Depending on CODEC/filter
Note:
C2
= 604 kΩ
= 604 kΩ
= 249 kΩ
= 280 kΩ
= 330 Ω
1% 1/10 W
DIODES:
DVB
1) RP1 and RP2 may be omitted if DVB is in place.
R2
1% 1/10 W
= 1N4448
= 1N4448
= 1N4448
R3
1% 1/10 W
DVB2
DBB
R4
1% 1/10 W
RRT
5% 2 W
RP1, RP2 ≥ 10 Ω
1% 1/10 W (Note 1)
RF1, RF2 = Line resistor, 40 Ω 1%
Figure 12. single-channel subscriber line interface with PBL 386 20/2 and combination CODEC/filter.
Overvoltage Protection
As the protection voltage will track the The fuse resistors RF serve the dual
negative supply voltage the overvoltage purposes of being non- destructive energy
stress on the SLIC is minimized.
dissipators, when transients are clamped
Positive overvoltages are clamped to gro- andofbeingfuses,whenthelineisexposed
und by a diode. Negative overvoltages are to a power cross.
initially clamped close to the SLIC negative If a PTC is choosen for RF , note that it is
supply rail voltage and the protector will important to always use PTC´s in series
crowbar into a low voltage on-state with resistors not sensitive to temperature,
The PBL 386 20/2 SLIC must be protected
against overvoltages on the telephone line
caused by lightning, ac power contact and
induction.RefertoMaximumRatings,TIPX
and RINGX terminals, for maximum
allowablecontinuousandtransientcurrents
that may be applied to the SLIC.
condition, by firing an internal thyristor.
asthePTCwillactasacapacitanceforfast
Secondary Protection
Agatedecouplingcapacitor,CGG,isneeded transients and therefore will not protect the
to carry enough charge to supply a high SLIC.
enough current to quickly turn on the
thyristorintheprotector.CGG shallbeplaced
close to the overvoltage protection device.
Without the capacitor even the low
inductanceinthetracktotheVBatsupplywill
limit the current and delay the activation of
the thyristor clamp.
Thecircuitshowninfigure12utilizesseries
resistors together with a programmable
overvoltage protector (e.g Power
Innovations TISPPBL2), serving as a
secondary protection.
The TISPPBL2 is a dual forward-conduc-
ting buffered p-gate overvoltage protector.
Theprotectorgatereferencestheprotection
(clamping) voltage to negative supply
voltage (i.e the battery voltage,VB ).
14
ERICSSON [ ERICSSON ]
