October 1998
PBL 386 50/1
Subscriber Line
Interface Circuit
Description
The PBL 386 50/1 Subscriber Line Interface Circuit (SLIC) is a 90 V bipolar integrated
circuit for use in Central Office Metering applications and other telecommunications
equipment. The PBL 386 50/1 has been optimized for low total line interface cost and
a high degree of flexibility in different applications.
The PBL 386 50/1 emulates resistive loop feed, programmable between 2x50
Ω
and 2x900
Ω,
with short loop current limiting adjustable to max 45 mA. In the current
limited region the loop feed is nearly constant current with a slight slope
corresponding to 2x30kΩ.
A second, lower battery voltage may be connected to the device to reduce short
loop power dissipation. The SLIC automatically switches between the two battery
supply voltages without need for external components or external control.
The SLIC incorporates loop current, ground key and ring trip detection functions.
The PBL 386 50/1 is compatible with both loop and ground start signaling.
Two- to four-wire and four- to two-wire voice frequency (VF) signal conversion is
accomplished by the SLIC in conjunction with either a conventional CODEC/filter or
with a programmable CODEC/filter, e.g. SLAC, SiCoFi, Combo II. The programmable
two-wire impedance, complex or real, is set by a simple external network.
Longitudinal voltages are suppressed by a feedback loop in the SLIC and the
longitudinal balance specifications meet Bellcore TR909 requirements.
The PBL 386 50/1 package options are 24-pin SOIC or 28-pin PLCC.
Key Features
· Programmable two-wire signal
headroom for 2.2 V
rms
metering
· High and low battery with automatic
switching
· Only +5 V feed in addition to battery
· Selectable transmit gain (0.5x or 0.25x)
· 70 mW on-hook power dissipation in
active state
· On-hook transmission
· Long loop battery feed tracks Vbat for
maximum line voltage
· No power-up sequence
· Tertiary protection arrangement
· 43V open loop voltage @
-48V battery feed
· Constant loop voltage for line leakage
<5 mA (RLeak ~ >10 kΩ @ -48V)
· Full longitudinal current capability
during on-hook state
· Analog over temperature protection
permits transmission while the
protection circuit is active
Ring Relay
Driver
RRLY
· Line voltage measurement
· Polarity reversal
· Ground key detector
· Tip open state with ring ground
detector
DT
DR
TIPX
RINGX
HP
Ring Trip
Comparator
Input
Decoder
and
Control
C1
C2
C3
DET
Ground Key
Detector
VCC
Two-wire
Interface
PLC
LP
PLD
VBAT2
38 PB
6 L
50
/1
Line Feed
Controller
and
Longitudinal
Signal
Suppression
POV
PSG
AGND
BGND
VF Signal
Transmission
VTX
RSN
PTG
24-pin SOIC, 28-pin PLCC
Figure 1. Block diagram.
4-225
P
B
L
38
REF
6
VBAT
Off-hook
Detector
50
/1
PBL 386 50/1
Maximum Ratings
Parameter
Symbol
Min
Max
Unit
Temperature, Humidity
Storage temperature range
Operating temperature range
Operating junction temperature range, Note 1
Power supply,
0°C
≤
T
Amb
≤
-70°C
V
CC
with respect to A/BGND
V
BAT2
with respect to A/BGND
V
Bat
with respect to A/BGND, continuous
V
Bat
with respect to A/BGND, 10 ms
Power dissipation
Continuous power dissipation at T
Amb
≤
+70
°C
Ground
Voltage between AGND and BGND
Relay Driver
Ring relay supply voltage
Ring trip comparator
Input voltage
Input current
Digital inputs, outputs
(C1, C2, C3, DET)
Input voltage
Output voltage
TIPX and RINGX terminals,
0°C < T
Amb
< -70°C
TIPX or RINGX current
TIPX or RINGX current, pulse < 10 ms, t
Rep
> 10 s
TIPX or RINGX current, pulse < 1 ms, t
Rep
> 10 s
TIPX or RINGX current, pulse < 10
µs,
t
Rep
> 10 s
TIPX or RINGX current, pulse < 1
µs,
t
Rep
>10 s
TIPX or RINGX current, pulse < 250 ns, t
Rep
> 10 s
T
Stg
T
Amb
T
J
V
CC
V
Bat2
V
Bat
V
Bat
P
D
V
G
-55
-40
-40
-0.4
V
Bat
-75
-80
+150
+110
+140
6.5
0.4
0.4
0.4
1.5
°C
°C
°C
V
V
V
V
W
V
-3
3
BGND+14 V
V
DT
, V
DR
I
DT
, I
DR
V
ID
V
OD
I
TIPX
, I
RINGX
I
TIPX
, I
RINGX
I
TIPX
, I
RINGX
I
TIPX
, I
RINGX
I
TIPX
, I
RINGX
I
TIPX
, I
RINGX
V
Bat
-5
-0.4
-0.4
AGND
5
V
CC
V
CC
+100
2
5
15
20
20
V
mA
V
V
-100
-2
-5
-15
-20
-20
mA
A
A
A
A
A
Recommended Operating Condition
Parameter
Symbol
Min
Max
Unit
Ambient temperature
V
CC
with respect to AGND
V
Bat
with respect to AGND
AGND with respect to BGND
T
Amb
V
CC
V
Bat
V
G
0
4.75
-65
-100
+70
5.25
-8
100
°C
V
V
mV
Notes
1.
The circuit includes thermal protection. Operation at or above 140°C junction temperature may degrade device reliability.
4-226
PBL 386 50/1
Electrical Characteristics
0
°C ≤
T
Amb
≤
+70
°C,
PTG = Open (see pin description), R
OV
=
∞,
V
CC
= +5V
±5
%, V
Bat
= -58V to -40V, V
Bat2
= -32V, R
LC
=32.4 kΩ, I
L
= 27 mA. R
L
= 600
Ω,
R
F1
= R
F2
= R
P1
= R
P2
=0, R
Ref
= 49.9 kΩ, C
HP
= 47 nF, C
LP
=0.15
µF,
R
T
= 60 kΩ, R
SG
= 0 kΩ, R
RX
= 60 kΩ, R
R
=
11 kΩ unless otherwise specified. Current definition: current is positive if flowing into a pin.
Parameter
Ref
fig
Conditions
Min
Typ
Max
Unit
Two-wire port
Overhead voltage, V
TRO
,I
Ldc
> 18mA
On-Hook, I
Ldc
< 5mA
Over load level, metering
Input impedance, Z
TR
Longitudinal impedance, Z
LoT
, Z
LoR
Longitudinal current limit, I
LoT
, I
LoR
Longitudinal to metallic balance, B
LM
(IEEE standard 455-1985, Z
TRX
=736Ω)
Longitudinal to metallic balance, B
LME
E
Lo
B
LME
= 20 · Log
V
TR
Longitudinal to four-wire balance, B
LFE
B
LFE
= 20 · Log
E
Lo
V
TX
4
2
Active state, R
OV
=
∞
0.2 kHz < f < 3.4 kHz
1% THD, Note 1
f≤16kHz, Z
LAC
=200Ω, Adj. by R
OV
Note 2
0 < f < 100 Hz
active state
Normal polarity:
0.2 kHz < f < 1.0 kHz
1.0 kHz < f < 3.4 kHz
Reverse polarity:
0.2 kHz < f < 3.4 kHz
Normal polarity:
0.2 kHz < f < 1.0 kHz
1.0 kHz < f < 3.4 kHz
Reverse polarity:
0.2 kHz < f < 3.4 kHz
0.2 kHz < f < 3.4 kHz
2.7
1.1
5.0
Z
T
/200
20
18
55
55
55
61
61
61
40
75
70
68
50
35
V
Peak
V
Peak
V
Peak
Ω/wire
mA
rms
/wire
dB
dB
dB
dB
dB
dB
dB
3
3
Metallic to longitudinal balance, B
MLE
E
TR
B
MLE
= 20 · Log
; E
RX
= 0
V
Lo
C
TIPX
VTX
Figure 2. Overhead voltage, V
TRO
, two-
wire port
1
<< R
L
, R
L
= 600
Ω
ωC
R
T
= 60 kΩ, R
RX
= 60 kΩ
R
L
V
TRO
I
LDC
PBL 386 50/1
RINGX
RSN
R
T
E
RX
R
RX
TIPX
E
Lo
VTX
Figure 3. Longitudinal to metallic (B
LME
)
and Longitudinal to four-wire (B
LFE
)
balance
1
<< 150
Ω,
R
LR
=R
LT
=R
L
/2=300Ω
ωC
R
T
= 60 kΩ, R
RX
= 60 kΩ
C
R
LT
V
TR
R
LR
RINGX
RSN
R
RX
PBL 386 50/1
R
T
V
TX
4-227
PBL 386 50/1
Ref
fig
Parameter
Conditions
Min
Typ
Max
Unit
Four-wire to longitudinal balance, B
FLE
4
Two-wire return loss, r
0.2 kHz < f < 3.4 kHz
E
B
FLE
= 20 · Log
RX
V
Lo
E
TR
source removed
|Z
TR
+ Z
L
|
r = 20 · Log
|Z
TR
- Z
L
|
0.2 kHz < f < 1.0 kHz
1.0 kHz < f < 3.4 kHz, Note 3
active, I
L
<5 mA
active, I
L
<5 mA
tip open, I
L
<5 mA
active, I
L
<5 mA
40
50
dB
27
20
TIPX idle voltage, V
Ti
RINGX idle voltage, V
Ri
V
TR
Four-wire transmit port
(VTX)
Overhead voltage, V
TXO
, I
L
> 18mA
On-hook, I
L
< 5mA
Output offset voltage,
∆V
TX
Output impedance, z
TX
Four-wire receive port
(RSN)
Receive summing node (RSN) DC voltage
Receive summing node (RSN) impedance
Receive summing node (RSN)
current (I
RSN
) to metallic loop current (I
L
)
gain,α
RSN
Frequency response
Two-wire to four-wire, g
2-4
6
5
35
22
- 1.3
V
Bat
+3.0
V
Bat
+3.0
V
Bat
+4.3
dB
dB
V
V
V
V
V
Peak
V
Peak
mV
Ω
V
Ω
ratio
Load impedance > 20 kΩ,
1% THD, Note 4
1.35
0.55
-100
0.2 kHz < f < 3.4 kHz
I
RSN
= -155
µA
0.2 kHz < f < 3.4 kHz
0.3 kHz < f < 3.4 kHz
1.15
0
15
1.25
8
200
100
50
1.35
20
relative to 0 dBm, 1.0 kHz. E
RX
= 0 V
0.3 kHz < f < 3.4 kHz
f = 8.0 kHz, 12 kHz, 16 kHz
-0.20
-1.0
0.10
0.1
dB
dB
TIPX
C
V
Lo
R
LT
V
TR
R
LR
RINGX
VTX
PBL 386 50/1
RSN
R
T
Figure 4. Metallic to longitudinal and four-
wire to longitudinal balance
E
RX
R
RX
1
<< 150
Ω,
R
LT
=R
LR
=R
L
/2 =300Ω
ωC
R
T
= 60 kΩ, R
RX
= 60 kΩ
C
R
L
I
LDC
E
L
TIPX
VTX
PBL 386 50/1
RINGX
RSN
R
T
V
TXO
Figure 5. Overhead voltage, V
TXO
, four-
wire transmit port
1
<< R
L
, R
L
= 600
Ω
ωC
R
T
= 60 kΩ, R
RX
= 60 kΩ
R
RX
4-228
PBL 386 50/1
Ref
fig
Parameter
Conditions
Min
Typ
Max
Unit
Four-wire to two-wire, g
4-2
6
Four-wire to four-wire, g
4-4
Insertion loss
Two-wire to four-wire, G
2-4
6
relative to 0 dBm, 1.0 kHz. E
L
=0 V
0.3 kHz < f < 3.4 kHz
f = 8 kHz, 12 kHz,
16 kHz
relative to 0 dBm, 1.0 kHz, E
L
=0 V
0.3 kHz < f < 3.4 kHz
0 dBm, 1.0 kHz, Note 5
V
G
2-4
= 20 · Log
TX
; E
RX
= 0
V
TR
PTG = AGND
0 dBm, 1.0 kHz, Note 6
V
G
4-2
= 20 · Log
TR
; E
L
= 0
E
RX
Ref. -10 dBm, 1.0 kHz, Note 7
-40 dBm to +3 dBm
-55 dBm to -40 dBm
Ref. -10 dBm, 1.0 kHz,
-40 dBm to +3 dBm
-55 dBm to -40 dBm
C-message weighting, 2 wire
Psophometrical weighting, 2 wire
C-message weighting, 4 wire
Psophometrical weighting, 4 wire
Note 8
-0.2
-1.0
-2.0
-0.2
0.1
0
0
0.1
dB
dB
dB
dB
6
-6.22
-12.24
-0.2
-6.02
-12.04
-5.82
-11.84
0.2
dB
dB
dB
Four-wire to two-wire, G
4-2
6
Gain tracking
Two-wire to four-wire
6
-0.1
-0.2
-0.1
-0.2
0.1
0.2
0.1
0.2
12
-78
6
-84
dB
dB
dB
dB
dBrnC
dBmp
dBrnC
dBmp
Four-wire to two-wire
6
Noise
Idle channel noise at two-wire
(TIPX-RINGX) or four-wire (VTX) output
Harmonic distortion
Two-wire to four-wire
Four-wire to two-wire
Battery feed characteristics
Loop current, I
L
, in the current
limited region, reference A, B & C
Tip open state TIPX current, I
Leak
Tip open state RINGX current, I
LRTo
Tip open state RINGX voltage, V
RTo
6
0 dBm
0.3 kHz < f < 3.4 kHz
-67
-67
-50
-50
dB
dB
13
7
18mA
≤
I
L
≤
45 mA
S = closed; R = 7 kΩ
R
LRTo
= 0Ω, V
Bat
= -48V
R
LRTo
= 2.5 kΩ, V
Bat
= -48V
I
LRTo
< 23 mA
0.92 I
L
I
L
1.08 I
L
-150
mA
µA
mA
mA
V
I
L
17
V
Bat
+6
Figure 6.
Frequency response, insertion loss,
gain tracking.
1
ωC
<< R
L
, R
L
= 600
Ω
C
TIPX
VTX
R
L
V
TR
E
L
I
LDC
PBL 386 50/1
RINGX
RSN
R
T
E
RX
V
TX
R
RX
R
T
= 60 kΩ, R
RX
= 60 kΩ
4-229
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