L3845 ,TRUNK INTERFACEL3845®TRUNK INTERFACEON CHIP POLARITY GUARDMEETS DC LINE CHARACTERISTICS OFEITHER CCITT AND EIA RS ..
L3845B ,TRUNK INTERFACEL3845TRUNK INTERFACEON CHIP POLARITY GUARDMEETS DC LINE CHARACTERISTICS OFEITHER CCITT AND EIA RS 4 ..
L3845D ,TRUNK INTERFACEELECTRICAL CHARACTERISTICS (I = 10 mA to 100 mA, R = 56 Ω, S = Open, T = + 25 °C,L 1 1 ambunless ..
L387 ,VERY LOW DROP 5V REGULATOR WITH RESETL387AVERY LOW DROP 5V REGULATOR WITH RESET. PRECISE OUTPUT VOLTAGE (5 V ± 4%). VERY LOW DROPOUT VOL ..
L387A ,VERY LOW DROP 5V REGULATOR WITH RESETL387AVERY LOW DROP 5V REGULATOR WITH RESET. PRECISE OUTPUT VOLTAGE (5 V ± 4 %). VERY LOW DROPOUT VO ..
L3916A ,SPEECH AND 14 MEMORY DIALER WITH LED DRIVERL3916A SPEECH AND 14 MEMORY DIALER WITH LED DRIVERSPEECH CIRCUIT2 TO 4 WIRES CONVERSIONPRESENT THE ..
LB1941T ,Brush Motor Drivers iForward/reverse driversj:Electrical Characteristics at Ta = 25°CRatingsParameter Symbol Conditions Unitmin typ maxStandby Cu ..
LB1941T-TLM-E , For Digital Cameras Constant Current Forward/Reverse Driver IC
LB1943 ,Forward/Reverse Motor Driver with Braking FunctionElectrical Characteristics at Ta = 25°C, V = 12 VCCRatingsParameter Symbol Conditions Unitmin typ m ..
LB1945H ,PWM Current Control Type Stepping Motor DriverElectrical Characteristics at Ta = 25
L3845
TRUNK INTERFACE
L3845TRUNK INTERFACE
ON CHIP POLARITY GUARD
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
DESCRIPTIONThe circuit provides DC loop termination for ana-
log trunk lines.
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 determined by 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
ABSOLUTE MAXIMUM RATINGS
THERMAL DATA(*) Mounted on FR4 Boards
PIN CONNECTION (Top view)
L38452/8
DC ELECTRICAL CHARACTERISTICS (IL = 10 mA to 100 mA, R1 = 56 Ω, S1 = Open, Tamb = + 25 °C,unless otherwise specified)
AC ELECTRICAL CHARACTERISTICS (IL = 10mA to 100mA, R1 = 56Ω, R2 = 470KΩ, R3 = 130 KΩ,Tamb = + 25 °C, unless otherwise specified)
(*) Not tested, guaranteed only by design.
APPLICATION INFORMATIONWith 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.
Figure 1 gives the typical application circuit ; it is
worth to note that the TRUNK TERMINATION
CIRCUIT, together with the LS5018 transient sup-
pressor provides a compact and low cost module
fully protected against lightning or overvoltages
frequently present on telephone lines.
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.
L38453/8
Figure 1: Typical Application.
L38454/8
L38455/8
(1) D and F do not include mold flash or protrusions. Mold flash or
potrusions shall not exceed 0.15mm (.006inch).
L38456/8
