STMICROELECTRONICS L3235

L3234
L3235
HIGHLY INTEGRATED SLIC KIT TARGETED TO PABX
AND KEY SYSTEM APPLICATIONS
HIGHLY INTEGRATED SUBSCRIBER LINE
INTERFACE KIT FOR PABX AND KEY SYSTEM APPLICATIONS
IMPLEMENTS ALL KEY ELEMENTS OF THE
BORSCHT FUNCTION
INTEGRATED ZERO CROSSING BALANCED
RINGING INJECTION ELIMINATES EXTERNAL RELAY AND CENTRALISED RINGING
GENERATOR
ZERO NOISE INJECTED ON ADJACENT
LINES DURING RINGING SEQUENCE
LOW POWER IN STANDBY AND ACTIVE
MODES
BATTERY FEED WITH PROGRAMMABLE
LIMITING CURRENT
PARALLEL LATCHED DIGITAL INTERFACE
SIGNALLING FUNCTIONS (OFF HOOK,
GND-KEY)
LOW NUMBER OF EXTERNAL COMPONENTS
INTEGRATED THERMAL PROTECTION
INTEGRATED OVER CURRENT PROTECTION
0°C TO 70°C: L3234/L3235
-40°C TO 85°C: L3234T/L3235T
DESCRIPTION
The L3234/L3235 is a highly integrated SLIC KIT
targeted to PABX and key system applications
The kit integrates the majority of functions required to interface a telephone line. The
L3234/L3235 implements the main features of the
broths function:
- Battery Feed (Balanced Mode)
- Ringing Injection
- Signalling Detection
- Hybrid Function
The Kit comprises 2 devices, the L3234 ringing
Janauary 1995
HEPTAWATT
ORDERING NUMBER: L3234
PLCC28
ORDERING NUMBER: L3235
injector fabricated in Bipolar in 140V Technology.
Its function is to amplify and inject in balanced
mode with zero crossing the ringing signal. The
device requires an external positive supply of
100V and a low level sinusoid of approx.
950mVrms. The L3235 Line Feeder is integrated
in 60V Bipolar Technology. The L3235 provides
battery feed to the line with programmable current
limitation. The two to four wire voice frequency
signal conversion is implemented by the L3235
and line terminating and balance impedances are
externally programmable. The L3234/L3235 kit is
designed for low power dissipation. In a short
loop condition the extra power is dissipated on an
external transistor. The Kit is controlled by five
wire parallel bus and interfaces easily to all first
and programmable second generation COMBOS.
(see figg. 1 and 2)
1/26
This is advanced information on a new product now in development or undergoing evaluation. Details are subject to change without notice.
L3234 - L3235
Figure 1: Typical Application Circuit with Second Generation COMBO for Complete Subscriber Circuit
(Protection-SLIC-COMBO)
2/26
L3234 - L3235
Figure 2: Typical Application Circuit with First Generation COMBO for Complete Subscriber Circuit
(Protection-SLIC-COMBO)
3/26
L3234 - L3235
L3234
Solid State Ringing Injector
DESCRIPTION
The L3234 is a monolithic integrated circuit which
is part of a kit of solid state devices for the subscriber line interface. The L3234 sends a ringing
signal into a two wires analog telephone line in
balanced mode. The AC ringing signal amplitude
is up to 60Vrms, and for that purpose a positive
supply voltage of +100V shall be available on the
subscriber card.
The L3234 receives a low amplitude ringing signal (950mVrms) and provide the voltage/current
amplification (60Vrms/70mA) when the enable input is active (CS > 2V). In disable mode (CS <
0.8V) the power consumption of the chip is very
low (<14mW).
The circuit is designed with a high voltage bipolar
technology (VCEO > 140V / VCBO > 250V).
BLOCK DIAGRAM
4/26
HEPTAWATT
The package is a moulded plastic power package
(Heptawatt) suitable also for surface mounting.
L3234 - L3235
PIN CONNECTION (Top view)
7
OUT2
6
V100
5
OUT1
4
GND
3
VCC
2
CS
1
VA
D94TL131
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
+120
V
5.5
V
Low Voltage Ringing Signal (with V100 = 120Vdc)
1.4
Vrms
Logical Ring Drive Input
VCC
Max. Junction Temperature
150
o
C
-55 to +150
o
C
V100
Positive Power Supply Voltage
VCC
5V Power Supply Voltage
VA
CS
Tj
Tstg
Storage Temperature
OPERATING RANGE
Symbol
Parameter
Value
Unit
V100
High Power Supply Voltage
95 to 105
V
VCC
Low Power Supply Voltage
5 ±5%
V
VA
Low Voltage Ringing Signal
600 to 950
within 10Hz - 100Hz
Vrms
Top
Operating Temperature for L3234
L3234T
0 to 70
-40 to 85
°C
°C
Tjop
Max. Junction Operating Temperature (due to thermal protection)
130
°C
Note: Operating ranges define those limits between which the functionality of the device is guaranteed.
THERMAL DATA
Symbol
Rth j-case
R th j-amb
Description
Value
Thermal Resistance Junction-case
Thermal Resistance Junction-ambient
Max.
Max.
4
50
Unit
o
o
C/W
C/W
PIN DESCRIPTION
Pin
Name
1
VA
Low Voltage Ringing Signal Input
Description
2
CS
Logical Ring Drive Input
3
VCC
+5V Low Power Supply
4
GND
Common Analog-Digital Ground
5
OUT1
Ringing Signal Output
6
V100
+100V High Power Supply
5/26
L3234 - L3235
OPERATION DESCRIPTION
The Fig. 3 show the simplified circuit configuration
of the L3234 Solid State Ringing injector when
used with the L3235 Line Feeder.
Figure 3: L3234/L3235Circuit Configuration
+100V
CO1
A
TIP
LINE TERMINALS
RING
B
CO2
V100
RO1
OUT1
RO2
OUT2
CS
CS
LINE FEEDER
GND
L3235
-VBAT
5
GND
+5V
C100
CVCC
GND
VCC
6
4
3
RINGING INJECTOR
7
L3234
2
1
VA
CA
VA
D94TL132
EXTERNAL COMPONENTS LIST
In the following table are shown the recommended external components values for L3234.
Ref.
Value
R01, R02
82Ω
Involved Parameter or Function
C01, C02
10µF - 160V
Ringing Feeding De coupling Capacitors
CA
4.7µF - 10V
Low Level Ringing Signal De coupling Capacitor
C100
100nF - 100V
CVCC
100nF
Ringing Feeding Series Resistors
Positive Battery Filter
+5V Supply Filter
When the ringing function is selected by the subscriber card, a low level signal is continuously applied to pin 1 through a de coupling capacitor. Then
the logical ring drive signal CS provided by L3235 is
applied to pin 2 with a cadenced mode.
The ringing cycles are synchronised by the L3234
in such a way that the ringing starts and stops always when the analog input signal crosses zero.
When the ringing injection is enabled (CS = ”1”),
an AC ringing signal is injected in a balanced
6/26
mode into the telephone line.
When the ringing injection is disabled (CS = ”0”),
the output voltage on OUT2 raises to the high
power supply, whereas on OUT1, it falls down to
ground.
The L3234 has a low output impedance when
sending the signal, and high output impedance
when the ringing signal is disabled
In fig. 4 the dynamic features of L3234 are
shown.
L3234 - L3235
Figure 4: Dynamic Features of L3234
DATA TRANSMISSION INTERFERENCE TEST
The L3234 meet the requirements of the technical
specification ST/PAA/TPA/STP/1063 from the
CNET. The test circuit used is indicated below.
The measured error rate for data transmission is
lower than 10-6 during the ringing phase.
This test measures if during the ringing phase the
circuit induce any noise to the closer lines.
Figure 5: Test Circuit Data Transmission Interference Test
7/26
L3234 - L3235
ELECTRICAL CHARACTERISTICS (Test conditions: V100 = +100V, VCC = +5V, Tamb = 25°C, unless otherwise specified)
Note: Testing of all parameter is performed at 25°C. Characterisation, as well as the design rule used allow correlation of tested performance with actual performances at other temperatures. All parameters listed here are met in the range 0°C to +70°C. For applications requiring operations in
the standard temperature range (0°C to 70°C) use L3234. If operations are required in the extended temperature range (-40°C to 85°C), use the L3234T.
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
45
560
100
800
µA
µA
6
92
V
V
70
70
kΩ
kΩ
Fig
STAND BY MODE: CS = ”0”
IS (V100)
IS (VCC)
Consumption
VA = 950mVrms; 50Hz
VSOUT1
VSOUT2
DC Output Voltage
VA = 950mVrms; 50Hz
ZSOUT1
ZSOUT2
Output Impedance
ZOUT Matching
THD
15
%
6
VLINE < 6dBm; f = 1kHz
-46
-40
dB
Consumption
ZLINE = ∞
VA = 950mVrms; 50Hz
2.5
2.2
5
3
mA
mA
DC Output Voltage
VA = 0V
44
44
56
56
V
V
Threshold Voltage on the
Logical Input CS
VA = 950mVrms; 50Hz
2.0
1
V
µA
0.8
1
V
µA
150
mA
12
9
Harmonic Distortion During
Emission
7
RINGING PHASE: CS = ”1”
DC OPERATION
IR (V100)
IR (VCC)
VROUT1
VROUT2
VIH
IIH (CS = 0)
VIL
IIL (CS = 0)
Ilim
DC Line Current Limitation
VA = 0V
70
8
AC OPERATION
VOUT1/VA
VOUT2/VA
VOUT1 -VOUT1
THD VLINE
ZIN (VA)
ZOUT
Ringing Gain
ZLINE = 2.2µF + 1kΩ
VA = 0dBm
Ringing Signal
ZLINE = 2.2µF + 1kΩ
VA = 950mVrms; 50Hz
Harmonic Distortion
VA = 950mVrms; 50Hz
Input Impedance
VA = 950mVrms; 50Hz
Differential Output Impedance
ILINE < 50mArms
TEST CIRCUITS
Figure 6.
8/26
29.5
29.5
30
30
dB
dB
57
60
Vrms
9
5
40
20
%
kΩ
10
Ω
11
L3234 - L3235
TEST CIRCUITS (continued)
Figure 7.
CS
2
VCC
V100
3
6
7
1
5
4
B
82Ω
L3234
4.7µF
10µF/160V
VOUT2
V
10µF/160V
A
VOUT1
ZLINE=600Ω
82Ω
-VBAT
1MΩ
GND
LINE FEEDER
VE 1KHz
D94TL133
Figure 8.
Figure 9.
9/26
L3234 - L3235
TEST CIRCUITS (continued)
Figure 10.
Figure 11.
Figure 12.
10/26
L3234 - L3235
L3235
Subscriber Line Interface Circuit
DESCRIPTION
Circuit description
The L3235 Subscriber Line Interface Circuit
(SLIC) is a bipolar integrated circuit in 60V technology optimized for PABX application.
The L3235 supplies a line feed voltage with a current limitation which can be modified by an external resistor (RLIM).
The SLIC incorporates loop currents, ground key
detection functions with an externally programmable constant time.
The two to four wires and four to two wires voice
frequency signal conversion is performed by the
L3235 and the line terminating and the balancing
impedances are externally programmable.
The device integrates an automatic power limitation circuit. In short loop condition the extra power
is dissipated on one external transistor (Text).
This aproach allows to assembly the L3235 in a
low cost standard plastic PLCC28 package.
The chip is protected by thermal protection at
Tj = 150°C.
The SLIC is able to give a power up command for
Combo in off hook condition and an enable logic
for solid state ringing injector L3234.
The L3235 package is 28 pin plastic PLCC.
The L3235 has been designed to operate
togheter with L3234 performing complete
BORSHT function without any electromechanical
ringing relay (see the application circuit fig. 16).
PLCC28
PIN CONNECTION
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
-54
V
VBAT
Battery Voltage
VCC
Positive Supply Voltage
5.5
V
VSS
Negative Supply Voltage
-5.5
V
Max. Junction Temperature
150
°C
-55 to +150
°C
Tj
Tstg
Storage Temperature
OPERATING RANGE
Symbol
Min.
Max.
Unit
VBAT
Battery Voltage
Parameter
-52
-24
V
VCC
Positive Supply Voltage
4.75
5.25
V
VSS
Negative Supply Voltage
-5.25
-4.75
V
Top
Operating Temperature for L3235
L3235T
0
-40
70
85
°C
°C
Tj
Max Junction Operating Temperature
130
°C
Note: Operating ranges define those limits between which the functionality of the device is guaranteed.
11/26
L3234 - L3235
THERMAL DATA
Symbol
R th j-amb
Description
Thermal Resistance Junction-ambient
Value
Unit
80
°C/W
Max
PIN DESCRIPTION
Pin
Name
1
Vbat
Description
2
RING
RING wire of 2 Wire Line Interface.
3
ZAC
Non Inverting Input of the AC Impedance Synthesis Circuit.
4
VREG
Emitter Connection for the External Transistor.
5
AGND
Analog/Digital Ground.
6
BGND
7
CAC
AC Current Feedback Input.
8
RPC
External Protection Resistors AC Transmission Compensation.
9
TX
Four Wire Transmitting Amplifier Output.
10
ZB
Non Inverting Operational Input Inserted in the Hybrid Circuit for 2W to 4W
Conversion. The Network Connected from this Pin to Ground shall be a copy
of the Line Impedance.
Negative Battery Supply Input.
Battery Ground. This is the Reference for the Battery Voltage (note 1).
11
ZA
VRX Output Buffer 2W to 4W Conversion.
12
RX
High Impedance Four Wire Receiving Input.
13
VCC
Positive 5V Supply Voltage.
14
REF
Voltage Reference Output; a Resistor Connected to this pin sets the Internal
Bias Current.
15
VSS
16
IL
17
VPOL
Non Inverting Operational Input to Implement DC Character.
18
BASE
Driver for External Transistor Base.
19
LIM
20
RNG
Ringing Logic Input from Line Card Controller.
21
SBY
Stand by Logic Input (SBY = 1 Set Line Current Limitation at 3mA).
22
PU
Power u.p Logic Output for the Codec Filter. (PU = 0 means Codec Filter
Activated)
23
CS
Ring Injector Enable for L3234 Output. (CS = 1 means L3234 Ringing
Injection Enable).
24
OH
Hook Status Logic Output (OH = 0 means off hook).
25
GDK
Ground Key Status Logic Output (GDK = 0 means Ground Key on).
26
RTF
Time Constant Hook Detector Filter Input.
27
GKF
Time Constant GK Detector Filter Input.
28
TIP
Tip Wire of 2 Wire Line Interface.
Negative 5V Supply Voltage.
Transversal Line Current Feedback Divided by 50.
Voltage Reference Output; a Resistor Connected to this Pin Sets the Value of
Line Current Limitation.
Note 1:
AGND and BGND pins must be tied together at a low impedance point (e.g. at card connector level).
12/26
L3234 - L3235
L3235 FUNCTIONAL DIAGRAM
FUNCTIONAL DESCRIPTION
DIGITAL INTERFACE
The different operating modes of the L3235 are
programmed through a digital interface based on
two input pins:
1)SBY input programs the stand-by or Active/Ringing modes.
2)RNG input programs the ringing ON/OFF activation condition for the L3234.
The L3235 digital interface has four output pins :
1)OH provides the on hook/off hook or ring trip
informations (active low).
2)GDK provides the ground key on/off information (active low).
3)PU must be connected to the enable input pin
of CODEC/FILTER devices like ETC 5054/57
and automatically activates this device when
in active mode off-hook is detected or when
ringing mode is selected.
4)CS output must be connected to the CS enable input of the solid state ringing injector
L3234.
In this way the L3234 will be enabled when ringing mode is programmed and will be automatically disabled when the ring trip condition will be
detected reducing the ringing signal disconnection time after ring trip.
The table 1 here below resumes the different operation modes and the relative logic output signals.
The two current detection (hook and GND key)
have internal fixed threshold. Externally it is possible to program their time costant through two R-C
components connected respectively to pin 26
(RTF) and pin 27 (GKF).
13/26
L3234 - L3235
Table 1.
OPERATING
MODE
ACTIVE
RINGING
STAND-BY
INPUT PIN
LINE STATUS
0: ON HOOK
1: OFF HOOK
OUTPUT PIN
0: NO GND KEY
1: GND KEY ON
OH
GDK
PU
CS
SBY
RNG
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
1
0
0
0
1
0
1
0
1
0
0
0
0
0
0
0
0
1
0
1
1
0
0
0
1
0
1
0
0
0
0
0
1
0(*)
0(*)
0(*)
1
1
0
1
X
X
X
X
1
1
1
1
1
0
0
1
(*)This status is latched and doesn’t change until RNG turn to 0
OPERATING MODES
Stand-By (SBY = 1 and RNG = 0)
In Stand-By mode the L3235 limits the DC Loop
current to 3 mA.
In this mode all the AC circuits are active and all
the AC characteristics are the same as in Active
Mode.
Also the two Line Current detectors (hook and
GND key) are active but due to the loop current
limited to 3 mA they will not be activated.
This mode is useful in emergency condition when
it is very important to limits the system power dissipation.
Ringing Mode (SBY = 0 and RNG = 1)
When ringing mode is selected ”CS” pin is set to
1 in order to activate the L3234 ringing injector.
See L3234 for detailed description.
Ring trip is detected by means of the same internal circuitry used for off-hook detection.
An off-hook delay time lower than 1⁄2 FRING should
be selected. (see ext. components list).
When ring trip is detected ”CS” is automatically
set to ”0” allowing in this way a quick ringing disconnection.
After Ring trip detection the Card Controller must
set the L3235 in active mode to remove the internal latching of the ”CS” information.
14/26
Active mode (SBY = 0 and CS1 = 0)
In Active mode the L3235 has the DC characteristic show in Fig.13
The DC characteristics of L3235 has two different
feeding conditions:
1)Current Limiting Region : (short loop) the DC
impedance of the SLIC is very high (>20
Kohm) therefore the system works as a current generator. By the ext. resistor RLIM connected at pin 19 it is possible to program limiting current values from 20 mA to 70 mA.
2) Voltage source region (long loop).
The DC impedance of the L3235 is almost
equal to zero therefore the system works like
a voltage generator with in series the two external protection resistors Rp.
When a limiting current value higher than 40 mA
is programmed the device will automatically reduce to 40 mA the loop current for very short
loop.
This is done in order to limit the maximum power
dissipation in very short loop to values lower than
2W for the external transistor and lower than
0.5W for the L3235 itself.
This improve the system reliability reducing the
L3235 power dissipation and therefore the internal junction temperature.
L3234 - L3235
Figure 13: DC characteristic in Active Mode with two different values of limiting current (30mA and 70 mA).
Figure 14: Line current versus loop resistance with two different values of limiting current (30mA and
70mA)
AC characteristic
A simplified AC model of the transmission circuits
is shown in figure 15.
Where :
Vrx
Vtx
Vl
Eg
Zl
is the received signal
is the transmitted signal
is the AC transversal voltage at line terminations.
is the line open circuit AC voltage
is the line impedance
Rp
ZB
ZA
ZAC
R PC
are the protection resistors
is the line impedance balancing network
is the SLIC impedance balancing network
program the AC line termination impedance
used for external protection resistors insertion
loss compensation
Il/50 is the AC transversal current divided by 50
CAC AC feedback current decoupling
15/26
L3234 - L3235
Figure 15: Simplified AC Circuits
Two wire impedance
To calculate the impedance presented to the two
wire line by the SLIC including the protection resistors R p and defined as ZS let:
Vrx = 0
Il/50’ = Il/50 (in first approximation)
Rp = 50Ω
ZS = Z AC/25 + 2RP
ZAC to make ZS = 600Ω
ZAC = 25 • (ZS - 2R P)
ZAC = 25 ⋅ (600 - 100)
ZAC = 12.5KΩ
Two wire to four wire gain (Tx gain)
Let Vrx = 0
Vtx
Gtx =
Vl
Vtx
ZAC + RPC
=2 ⋅
Vl
ZAC + 50RP
Example: Calculate Gtx making RPC = 50 ⋅ RP
ZAC + 50 ⋅ RP
Gtx = 2 ⋅
=2
ZAC + 50 ⋅ RP
As you can see the RPC resistor is providing the
compensation of the insertion loss introduced by
the two external protection resistors RP.
Four wire to two wire gain (Rx gain)
Let Eg = 0
Vl
50 ⋅ Zl
Grx =
=
Vrx
25⋅ (Zl + 2RP ) + ZAC
Example:
Calculate Grx making ZAC = 25 ⋅ (ZML - 2 ⋅ RP)
50 ⋅ Zl
Grx =
25 ⋅ (Zl + 2RP − 2RP + ZML)
16/26
Grx =
2 ⋅ Zl
Zl + ZML
In particular for ZS = Z l: Grx = 1
Hybrid function
To calculated the transhybrid loss (Thl) let: Eg = 0
Thl =
ZB
50 ⋅ ( 2 ⋅ RP + Zl ) − 2RPC
VTx
=4(
+ ZA −
)
=
VRx
ZB
50 ⋅ ( 2 ⋅ RP + Zl ) − 2RAC
Example:
Calculating Thl making RS = 50 ⋅ RP, ZS = 25 ⋅
(ZSlic - 2 ⋅ RP)
ZB
Zl
Thl = 4 ⋅ (
−
)
ZB + ZA Zl + ZML
In particular if
ZS
ZA
=
ZB
Zl
Thl = 0
From the above relation it is evident that if ZS is
equal to the Zl used in Thl test, the two ZA, ZB impedances can be two resistor of the same value.
AC transmission circuit stability
To ensure stability of the feedback loop shown in
block diagram form in figure 15 two capacitors are
required. Figure 16 includes these capacitors Cc
and Ch.
AC - DC separation
The high pass filter capacitor CAC provides the
separation between DC circuits and AC circuits. A
CAC value of 100mF will position the low end frequency response 3dB break point at 7Hz,
fsp =
1
2π ⋅ 220Ω ⋅ CAC
L3234 - L3235
External components list for L3235
To set the SLIC into operation the following parameters have to be defined:
- The AC SLIC impedance at line terminals ”Zs” to which the return loss measurements is referred. It can
be real (typ. 600Ω) or complex.
- The equivalent AC impedance of the line ”Zl” used for evaluation of the trans-hybrid loss performance
(2/4 wire conversion). It is usually a complex impedance.
- The value of the two protection resistors Rp in series with the line termination.
Once, the above parameters are defined, it is possible to calculate all the external components using the
following table. The typical values has been obtained supposing: Zs = 600Ω; Zl = 600Ω; Rp = 50Ω
Name
RF
CF
R GF
C GF
RR
RLIM
Suggested Value
39KΩ
390nF
39KΩ
390nF
51KΩ
8.4KΩ to 33KΩ
Function
Delay Time
On-hook Off-hook
Delay Time
GK Detector
Bias Set
Ext. Current Limit. Progr.
CR
4.7µF
6.3 V 30%
Negative Battery
Filter
RP
RT
CAC
50
1MΩ 20%
100µF
6.3V 20%
Protection Resistors
Termination Resistor
DC/AC current feedback splitting
RPC
ZAC
CC
2500Ω 1%
12500Ω 1%
220pF 20%
RP insertion loss compensation
2W AC Impedance programmation
AC Feedback compensation
ZAS
R AS
ZB
CH
12500Ω 1%
2500Ω 1%
15KΩ 1%
220pF 20%
Slic Impedance Balancing Net.
Line impedance Balancing Net.
CC Transybrid loss Compensation
CTX
4.7µF 30%
DC Decoupling Tx Output
D1, D2
Text
1N4007
(3)
CVSS; CVDD
C VB
100nF
100nF/100V
Line Rectifier
External Transistor
Formula
τ = 0.69 ⋅ CF ⋅ 39KΩ
(1)
τ = 0.69 ⋅ C GF ⋅ 39KΩ
RLIM =
564
ILIM − 3mA
1
2π ⋅ 16KΩ ⋅ fp
47 < RP < 100Ω (2)
CAC =
CAC =
1
2π ⋅ 220Ω ⋅ fsp
R PC = 25 ⋅ (2RP)
ZAC = 25 ⋅ (ZS - 2RP)
f1 = 300KHz
CC =
1
2πf1 ⋅ 50RP
ZAS = 25 ⋅ (ZS - 2RP)
RAS = 25 ⋅ (2RP)
ZB = 25 ⋅ Zl
C H = CC ⋅
CTX =
ZAC
ZAS
1
6.28 ⋅ fp ⋅ Zload
PDiss > 2W, VCEO > 60V
H FE > 40, IC > 100mA
VBE < 0.8V @ 100mA
±5V supply filter
VBAT supply filter
Notes:
1) For proper operation Cf should be selected in order to verify the following conditions:
A) cf > 150nF
B) τ < 1/2 • fRING
fRING: Ringing signal frequency
2) For protection purposes the RP resistor is usually splitted in two part RP1 and RP2, with RP1 > 30Ω.
3) ex: BD140; MJE172; MJE350.... (SOT32 or SOT82 package available also for surface mount). For low power application (reduced battery
voltage) BCP53 (SOT223 surface mount package) can be used. Depending on application enviroment an heatsink could be necessary.
17/26
L3234 - L3235
Figure 16: Typical Appication Circuit Including L3234 and Protection
18/26
L3234 - L3235
ELECTRICAL CHARACTERISTICS (Test condition: refer to the test circuit of the fig. 17; VCC = 5V,
VSS = -5V, Vbat = -48V, Tamb = 25°C, unless otherwise specified)
Note: Testing of all parameters is performed at 25°C. Characterization, as well as the design rules used
allow correlation of tested performance with actual performance at other temperatures. All parameters listed here are met in the range 0°C to +70°C. For applications requiring operations in
the standard temperature range (0°C to 70°C) use L3234. If operations are required in the extended temperature range (-40°C to 85°C), use the L3234T.
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
39
V
3
4
mA
70
39
39
77
70
5
V
V
mA
mA
Fig.
STAND-BY
Vls
ILCC
Output Voltage at TIP/RING
pins
Short Circuit Current
ILINE = 0
Stand-by, SBY = 1
35.7
2
DC OPERATION
VlP
Ilim
Ilim
IO
If
Ilgk
Gklim
Gkov
Imax
IVCC
IVSS
IVbat
Output Voltage at TIP/RING
pins
Current Progr.
Current Progr.
On-hook Threshold
Off-hook Threshold
GK Detector Threshold
Ground Key Current
Limitation
Ground Key Threshold
Overloap
Max. Output Current at
TIP/RING
Supply Current from VCC
Supply Current from VSS
Supply Current from Vbat
ILINE = 0
ILINE = 50mA
Ilim Prog. = 70mA
8.4KΩ < RLIM < 33KΩ
35.7
35.2
63
20
RING to BGND
10
10
13
Gklim-Ilgk
1
Ilim = 70mA
90
Iline = 0
Iline = 0
Iline = 0
17
22
mA
mA
6.2
1.6
2.8
140
mA
8
2.1
3.6
mA
mA
mA
10
Ω
MΩ
dB
dB
dB
dB
dB
dB
dB
dB
dBmp
dBmp
dB
dB
dB
dB
AC OPERATION
Ztx
Zrx
Rl
Thl
Gs
Gsf
Gsl
Gr
Grf
Grl
Np4W
Np2W
Svrr
Svrr
L tc
Tlc
Sending Output Impedance
Receiving Input Impedance
2W Return Loss
Trans Hybrid Loos
Sending Gain
Flatness
Linearity
Receiving Gain
Flatness
Linearity
Psoph. Noise at Tx
Psoph. Noise at Line
Relative to Vbat versus Line
Terminal versus Tx Terminal
Relative to Vcc and Vss
versus Line Terminal versus
Tx Terminal
L/T Conversion measured at
line Terminals
T/L Conversion Measured at
Line Terminals
pin 9 (Tx)
pin 12 (Rx)
f = 300 to 3400Hz
f = 300 to 3400Hz
f = 1020Hz Il = 20mA
f = 300 to 3400Hz
-20dB to 10dBm
f = 1020Hz Il = 20mA
f = 300 to 3400Hz
-20dBm to +4dBm
1
20
20
5.82
-0.2
-0.2
0.2
-0.2
-0.2
36
36
6.02
0
-69
-75
f = 1020Hz
VS = 100mVpp
f = 1020Hz
VS = 100mVpp
f = 300 to 3400
Iline = 20mA
f = 300 to 3400
Iline = 20mA
49
53(*)
46(*)
6.22
0.2
0.2
0.2
0.2
0.2
-62
-68
-30
-24
-20
-14
dB
dB
dB
A1
A2
A3
A4
A5
A6
A7
(*) Selected parts L3235C
19/26
L3234 - L3235
ELECTRICAL CHARACTERISTICS (continued)
Symbol
Parameter
Test Condition
Min.
Typ.
Max.
Unit
V
DIGITAL STATIC INTERFACE
Vil
Input Voltage at Logical ”0”
Input SBY, CS1
0
0.8
Vih
Input Voltage at Logical ”1”
Input SBY, CS1
2
5
V
Iil
Input Current at Logical ”0”
Input SBY, CS1
10
µA
Iih
Input Current at Logical ”1”
Input SBY, CS1
10
µA
Vol
Output Voltage at Logical ”0”
Iout = 1mA
Iout = 10µA
0.5
0.4
V
V
Voh
Output Voltage at Logical ”1”
Iout = 10µA
Iout = 1mA
Figure 17: Test Circuit
20/26
4
2.7
V
V
Fig.
L3234 - L3235
In particular:
A-B: Line terminals
C: Tx sending output on 4W side
D: Rx receiving input on 4W Side
APPENDIX A
L3235 TEST CIRCUITS
Referring to the test circuit reported in fig 17 you
can find the proper configuration for the main
measurements.
Figure A1: 2W Return Loss
100µF
100µF
RL = 20 log
| ZML − Z |
| ZML + Z |
= 20 log
| 2VS |
|E|
Figure A2: Trans-hybrid Loss
100µF
THL = 20log
VS
VR
100µF
Figure A3: Sending Gain
100µF
100µF
21/26
L3234 - L3235
TEST CIRCUITS (continued)
Figure A4: Receiving Gain
100µF
100µF
Figure A5: SVRR Relative to Battery Voltage VB
100µF
100µF
Figure A6: Longitudinalto Transversal Conversion
22/26
L3234 - L3235
Figure A7: Transversal to LongitudinalConversion
APPENDIX B
LAYOUT SUGGESTIONS
Standard layout rules should be followed in order
to get the best system performances:
1) Use always 100nF filtering capacitor close to
the supply pins of each IC.
2) The L3235 bias resistor (RR) should be connected
close to the corresponding pins of L3235
(REF and AGND).
23/26
L3234 - L3235
HEPTAWATT (Surface Mount) PACKAGE MECHANICAL DATA
mm
DIM.
MIN.
TYP.
inch
MAX.
TYP.
MAX.
4.8
0.189
C
1.37
0.054
D
2.4
2.8
0.094
0.110
D1
1.2
1.35
0.047
0.053
E
0.35
0.55
0.014
0.022
F
0.6
0.8
0.024
F1
0.031
0.9
0.035
G
2.41
2.54
2.67
0.095
0.100
0.105
G1
4.91
5.08
5.21
0.193
0.200
0.205
G2
7.49
7.62
7.8
0.295
0.300
H2
9.2
10.4
0.362
0.409
H3
10.05
10.4
0.396
0.409
L
4.6
5.05
0.181
L1
3.9
4.1
4.3
0.153
0.161
0.170
L2
6.55
6.75
6.95
0.253
0.265
0.273
L3
5.9
6.1
6.3
0.232
0.240
0.248
L5
2.6
2.8
3
0.102
0.110
0.118
L6
15.1
15.8
0.594
0.622
L7
6
6.6
0.236
0.260
M
0.17
0.32
0.007
0.012
0.144
0.152
V2
Dia
24/26
MIN.
A
0.307
0.198
8°(max)
3.65
3.85
L3234 - L3235
PLCC28 PACKAGE MECHANICAL DATA
mm
DIM.
MIN.
TYP.
inch
MAX.
MIN.
TYP.
MAX.
A
12.32
12.57
0.485
0.495
B
11.43
11.58
0.450
0.456
D
4.2
4.57
0.165
0.180
D1
2.29
3.04
0.090
0.120
D2
0.51
E
9.91
0.020
10.92
0.390
0.430
e
1.27
0.050
e3
7.62
0.300
F
0.46
0.018
F1
0.71
0.028
G
0.101
0.004
M
1.24
0.049
M1
1.143
0.045
25/26
L3234 - L3235
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 products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics.
 1995 SGS-THOMSON Microelectronics - All Rights Reserved
SGS-THOMSON Microelectronics GROUP OF COMPANIES
Australia - Brazil - France - Germany - Hong Kong - Italy - Japan - Korea - Malaysia - Malta - Morocco - The Netherlands - Singapore Spain - Sweden - Switzerland - Taiwan - Thaliand - United Kingdom - U.S.A.
26/26