L3845B [STMICROELECTRONICS]
TRUNK INTERFACE; Trunk接口型号: | L3845B |
厂家: | ST |
描述: | TRUNK INTERFACE |
文件: | 总7页 (文件大小:60K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
L3845
TRUNK INTERFACE
ON CHIP POLARITYGUARD
MEETS DC LINE CHARACTERISTICS OF
EITHER CCITT AND EIA RS 464 SPECS
PULSE FUNCTION
HIGH AC IMPEDANCE
OFF HOOK-STATUS DETECTION OUTPUT
LOW EXTERNAL COMPONENT COUNT
Minidip
SO8
DESCRIPTION
The circuit provides DC loop termination for ana-
log trunklines.
ORDERING NUMBERS:
L3845B
L3845D
The V-I characteristics is equivalent to a fixed
voltage drop (zener like characteristic) in series
with an external resistance that determines the
slope of the DC characteristic.
An external low voltage electrolytic capacitor
causes the circuit to exhibit a very high imped-
ance to all AC signal above a minimum frequency
that is determinedby the capacitor itself and by a
20 K nominal resistor integrated on the chip.
The Off-Hook status is detected all the time a
typic of 8 mA is flowing into the circuit. In this con-
dition a constant current generator is activated to
supply an external device (typically an optocou-
pler) without affecting the AC characteristic of the
circuit.
When Pulse Dialing is required the PULSE input
(pin 3) connected to V- causes the device to re-
duce the fixed DC voltage drop and to exhibit a
pure resistive impedance equal to the external re-
sistor.
BLOCK DIAGRAM
8
1
V+
IN1
3
PULSE
DC LINE
TERMINATION
POLARITY
GUARD
OF HOOK
DETECTION
CIRCUIT
4
HD0
7
IN2
5
6
2
ACT
DCT
V-
R2
R3
C1
S2
R1
S1
D96TL263
1/7
June 1996
This is advanced information on a new product now in development or undergoingevaluation. Details are subject to change without notice.
L3845
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
20
Unit
V
VL
IL
Max Line Voltage (pulse duration 10 ms max)
Max Line Current
150
mA
mW
°C
Ptot
Total Power Dissipation at Tamb = 70 °C
Operating Temperature
800
Top
– 40 to + 70
– 55 to + 150
Tsrg, Tj
Storage and Junction Temperature
°C
PIN CONNECTION (Topview)
THERMAL DATA
Symbol
Parameter
Thermal Resistance Junction-ambient (*)
Minidip
80
SO8
Unit
Rth j-amb
Max.
140 to 180
C/W
°
(*) Mounted on FR4 Boards
2/7
L3845
DC ELECTRICAL CHARACTERISTICS
unless otherwise specified)
Ω
°
(IL = 10 mA to 100 mA, R1 = 56 , S1 = Open, Tamb = + 25 C,
Symbol
Parameter
Line Voltage
Test Condition
PULSE = Open
Min.
Typ.
Max.
Unit
VL
(normal mode)
IL = 10 mA
IL = 20 mA
IL = 100 mA
5
6
12
V
V
V
VLP
Line Voltage
(pulse mode)
PULSE = V–
IL = 20 mA
IL = 35 mA
IL = 80 mA
4
5.5
9.5
V
V
V
Ihn
ON/OFF-Hook
Line Current Detection
Threshold
6.5
5
9.5
9.2
mA
Ihf
OFF/ON-Hook
Line Current Detection
Threshold
mA
IOUT
OFF-Hook
Output Drive Current at Pin
HDO
IL = 10 mA
IL 20 mA
≥
1.5
2
mA
mA
VPM
IPM
Pulse Input Low Voltage
0.8
20
V
Pull-up Input Current at Pin
PULSE (pulse mode)
IL = 100 mA
Pulse = V–
µA
INM
Imput Current at Pin Pulse
(normal mode)
3
A
µ
AC ELECTRICAL CHARACTERISTICS (IL = 10mA to 100mA, R1 = 56Ω, R2 = 470KΩ, R3 = 130 KΩ,
amb = + 25 °C, unless otherwise specified)
T
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
ZL
AC Line Impedance
S1 = Open, S2 = Open
C1 = 2.2mF
f = 1KHz
20
K
Ω
Sending/Receiving Distortion
S1 = Open, S2 = Open
f = 1KHz
V
AC-L = 775mVrms
2
%
IL = 15 to 100mA
Sending/Receiving Distortion
Sending/Receiving Distortion
S1 = Closed; S2 = Open
V
AC-L = 1.3Vrms
S1 = Open; S2 = Closed
AC-L = 1.9Vrms
2
%
%
2(*)
V
(*) Not tested, guaranteed only by design.
APPLICATION INFORMATION
Figure 1 gives the typical application circuit ; it is
worth to note that the TRUNK TERMINATION
CIRCUIT, togetherwith the LS5018 transient sup-
pressor provides a compact and low cost module
fully protected against lightning or overvoltages
frequently present on telephonelines.
The PULSE input when connected to V- allows
the device to reduce the Line Voltage and to
show a resistive impedance equal to R1 to the
line. When PULSE input is left open, this function
is disable.
With the use of this circuit it is possible to termi-
nate an analog trunk so that all the DC current
component is flowing in the TRUNK TERMINA-
TION CIRCUIT while the AC component is de-
coupled with a low voltage capacitor and can be
used with a small and low cost audio coupler
transformer to provide the AC balancing termina-
tion and two to four wire conversion.
Therefore it is usefull both for MODEM and PABX
systems.
3/7
L3845
Figure 1:
Typical Application.
4/7
L3845
MINIDIP PACKAGE MECHANICAL DATA
mm
inch
Typ.
DIM
Min.
Typ.
Max.
Min.
Max.
A
a1
B
3.32
0.131
0.51
1.15
0.020
0.045
0.014
0.008
1.65
0.55
0.065
0.022
0.012
0.430
0.384
b
0.356
0.204
b1
D
E
0.304
10.92
9.75
7.95
0.313
e
2.54
7.62
7.62
0.100
0.300
0.300
e3
e4
F
6.6
0260
0.200
0.150
0.060
i
5.08
3.81
1.52
L
3.18
0.125
Z
5/7
L3845
SO8 PACKAGE MECHANICAL DATA
mm
inch
Typ.
DIM
Min.
Typ.
Max.
1.75
0.25
1.65
0.85
0.48
0.25
0.5
Min.
Max.
0.069
0.010
0.065
0.033
0.019
0.010
0.020
A
a1
a2
a3
b
0.1
0.004
0.65
0.35
0.19
0.25
0.026
0.014
0.007
0.010
b1
C
c1
D
45o (typ.)
4.8
5.8
5.0
6.2
0.189
0.228
0.197
0.244
E
e
1.27
3.81
0.050
0.150
e3
F
3.8
0.4
4.0
1.27
0.6
0.150
0.016
0.157
0.050
0.024
L
M
S
8o (max.)
6/7
L3845
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no
responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights
of SGS-THOMSON Microelectronics. Specifications mentioned in this publication are subject to change without notice.
This publication supersedes and replaces all information previously supplied. SGS-THOMSON Microelectronics prod-
ucts are not authorized for use as critical components in life support devices or systems without express written ap-
proval of SGS-THOMSON Microelectronics.
1994 SGS-THOMSON Microelectronics - All Rights Reserved
SGS-THOMSON Microelectronics GROUP OF COMPANIES
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7/7
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