Datasheet L3234, L3235 Datasheet (SGS Thomson Microelectronics)

HIGHLY INTEGRATEDSLIC 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
BORSCHTFUNCTION

INTEGRATEDZERO 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
LIMITINGCURRENT

PARALLELLATCHED DIGITAL INTERFACE
SIGNALLING FUNCTIONS (OFF HOOK,

GND-KEY)
LOW NUMBER OF EXTERNAL COMPO-

NENTS
INTEGRATEDTHERMAL PROTECTION
INTEGRATED OVER CURRENT PROTEC-

TION
0°CTO70°C: L3234/L3235

-40°CTO85°C: L3234T/L3235T

L3234
L3235

HEPTAWATT

ORDERING NUMBER: L3234

PLCC28

ORDERING NUMBER: L3235

injectorfabricatedin Bipolarin 140V Technology.
Its function is to amplify and inject in balanced

mode with zero crossing the ringing signal. The

DESCRIPTION

The L3234/L3235is a highly integrated SLIC KIT
targeted to PABX and key systemapplications

The kit integrates the majority of functions re­quired to interface a telephone line. The
L3234/L3235implementsthe main featuresof the
broths function:

- Battery Feed (BalancedMode)

- Ringing Injection

- Signalling Detection

- Hybrid Function
The Kit comprises 2 devices, the L3234 ringing

Janauary 1995

This isadvanced information on a new product now in development or undergoing evaluation.Details are subject to change without notice.

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
batteryfeed tothe line with programmablecurrent
limitation. The two to four wire voice frequency
signal conversion is implemented by the L3235
and line terminating and balance impedancesare
externally programmable. The L3234/L3235kit is
designed for low power dissipation. In a short
loop conditionthe extrapower 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.
(seefigg. 1 and 2)

1/26

L3234 - L3235

Figure1: Typical ApplicationCircuit with SecondGeneration COMBO for Complete Subscriber Circuit

(Protection-SLIC-COMBO)

2/26

L3234 - L3235

Figure2: Typical ApplicationCircuit with First GenerationCOMBO for Complete Subscriber Circuit

(Protection-SLIC-COMBO)

3/26

L3234 - L3235

L3234

Solid State Ringing Injector

DESCRIPTION

The L3234 is a monolithic integratedcircuit 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
subscribercard.

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 highvoltage bipolar
technology(V

>140V / V

CEO

CBO

>250V).

HEPTAWATT

The packageis a moulded plastic power package
(Heptawatt)suitable also for surface mounting.

BLOCK DIAGRAM

4/26

PIN CONNECTION (Top view)

L3234 - L3235

7
6
5
4
3
2
1

D94TL131

OUT2
V100
OUT1
GND
VCC
CS
VA

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V100 Positive Power SupplyVoltage +120 V

V

V

CS Logical Ring DriveInput V

T

T

5V Power Supply Voltage 5.5 V

CC

Low Voltage Ringing Signal (with V100 = 120Vdc) 1.4 Vrms

A

CC

Max. Junction Temperature 150

j

Storage Temperature -55 to +150

stg

OPERATINGRANGE

Symbol Parameter Value Unit

V100 High Power Supply Voltage 95 to 105 V

V

V

T

T

Low Power Supply Voltage 5 ±5% V

CC

Low Voltage Ringing Signal

A

Operating Temperature for L3234

op

Max. Junction Operating Temperature (due to thermal protection) 130 °C

jop

L3234T

600 to 950

within 10Hz -100Hz

0to70

-40 to 85

o

C

o

C

Vrms

°C
°C

Note: Operating ranges definethose limits between which the functionality ofthe device is guaranteed.

THERMAL DATA

Symbol Description Value Unit

R

th j-case

R

th j-amb

Thermal ResistanceJunction-case
Thermal ResistanceJunction-ambient

Max.
Max.

4

50

PIN DESCRIPTION

Pin Name Description

1 VA Low Voltage Ringing Signal Input
2 CS Logical Ring Drive Input
3V

CC

4 GND Common Analog-Digital Ground
5 OUT1 Ringing Signal Output
6 V100 +100V High Power Supply

+5V Low Power Supply

o

C/W

o

C/W

5/26

L3234 - L3235

OPERATIONDESCRIPTION

The Fig. 3 show the simplifiedcircuit configuration

Figure3: L3234/L3235Circuit Configuration

CO1

CO2

RO1

RO2

TIP

LINE TERMINALS

RING

LINE FEEDER

A

B

L3235

of the L3234 Solid State Ringing injector when
used with the L3235 Line Feeder.

+5VGND+100V

C100 CVCC

VCCGNDV100

643

CS

5

RINGING INJECTOR

7

L3234

2

CA

1

VA

VA

D94TL132

OUT1

OUT2

CS

GND

-VBAT

EXTERNALCOMPONENTSLIST

In the followingtable are shown the recommendedexternalcomponentsvalues for L3234.

Ref. Value Involved Parameter or Function

R01, R02 82Ω Ringing Feeding SeriesResistors
C01, C02 10µF - 160V Ringing Feeding Decoupling Capacitors

CA 4.7µF - 10V Low LevelRinging Signal De coupling Capacitor
C100 100nF - 100V Positive Battery Filter
CV

CC

When the ringing function is selected by the sub­scriber card, a low level signal is continuously ap­plied to pin 1 througha de couplingcapacitor.Then
thelogicalringdrivesignalCS providedby L3235is
appliedto pin2 witha cadencedmode.

The ringing cycles are synchronised by the L3234
in such a way that the ringing starts and stops al­wayswhenthe analoginputsignalcrosses zero.

When the ringing injection is enabled (CS = ”1”),
an AC ringing signal is injected in a balanced

6/26

100nF +5V Supply Filter

modeinto thetelephone 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.

Figure4: Dynamic Features of L3234

L3234 - L3235

DATATRANSMISSION INTERFERENCE TEST

The L3234 meet the requirementsof 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

This test measuresif during the ringing phase the
circuitinduce any noise to the closer lines.

Figure5: Test CircuitData TransmissionInterferenceTest

-6

during the ringing phase.

7/26

L3234 - L3235

ELECTRICAL CHARACTERISTICS (Test conditions:V100 = +100V,VCC= +5V, T

=25°C, unless oth-

amb

erwise specified)
Note: Testing of all parameteris performed at 25°C. Characterisation,as well as the design rule used al-

low 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°Cto70°C) use L3234. If operations are required in the ex-
tended temperaturerange (-40°Cto85°C), use theL3234T.

Symbol Parameter Test Condition Min. Typ. Max. Unit Fig

STANDBY MODE: CS = ”0”

IS(V100)

I

S(VCC

V

SOUT1

V

SOUT2

Z

SOUT1

Z

SOUT2

THD Harmonic Distortion During

Consumption VA = 950mVrms; 50Hz 45

)

DC Output Voltage VA = 950mVrms; 50Hz

Output Impedance 70

Z

Matching 15 %

OUT

< 6dBm; f = 1kHz -46 -40 dB 7

V

LINE

Emission

92

70

560

100
800

µA
µA

6V

V

kΩ
kΩ

6

RINGINGPHASE: CS = ”1”
DC OPERATION

IR(V100)

I

)

R(VCC

V

ROUT1

V

ROUT2

V

IH

IIH(CS = 0)

V

IL

IIL(CS = 0)

I

lim

Consumption Z

DC Output Voltage VA = 0V 44

Threshold Voltage on the
Logical Input CS

DC Line Current Limitation VA = 0V 70 150 mA 12

= ∞

LINE

VA = 950mVrms; 50Hz

44

VA = 950mVrms; 50Hz 2.0

2.5

2.2

5
3

56
56

1

0.8
1

mA
mA

V
V

V

µA

V

µA

8

AC OPERATION

V

/VA

OUT1

V

/VA

OUT2

V

OUT1-VOUT1

Ringing Gain Z

Ringing Signal ZLINE = 2.2µF+1kΩ

= 2.2µF+1kΩ

LINE

VA = 0dBm

29.5

29.5

30
30

57 60 Vrms

VA = 950mVrms; 50Hz

THDV

(VA) InputImpedance VA = 950mVrms; 50Hz 40 kΩ 10

Z

IN

Z

OUT

Harmonic Distortion VA = 950mVrms; 50Hz 5 %

LINE

Differential Output Impedance I

< 50mArms 20 Ω 11

LINE

TEST CIRCUITS
Figure6.

8/26

dB
dB

9

9

TEST CIRCUITS (continued)
Figure7.

VCC V100

L3234 - L3235

Figure8.

4.7µF

CS

2

1

L3234

4

GND

D94TL133

VOUT2

63

7

VOUT1 A

5

82Ω

82Ω

10µF/160V

10µF/160V

-VBAT

LINE FEEDER

1MΩ

B

V

ZLINE=600Ω

VE 1KHz

Figure9.

9/26

L3234 - L3235

TEST CIRCUITS (continued)
Figure10.

Figure11.

Figure12.

10/26

L3235

Subscriber Line Interface Circuit

DESCRIPTION
Circuitdescription

The L3235 Subscriber Line Interface Circuit
(SLIC) is a bipolar integrated circuit in 60V tech­nologyoptimized 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
detectionfunctionswith an externallyprogramma­ble 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
impedancesare externallyprogrammable.

The device integrates an automatic power limita­tion circuit. In shortloop conditionthe extrapower
isdissipated on one external transistor (Text).

This aproach allows to assembly the L3235 in a
low cost standardplastic PLCC28 package.

The chip is protected by thermal protection at
Tj = 150°C.

The SLIC is able to givea powerup commandfor
Combo in off hook condition and an enable logic
for solidstate ringing injectorL3234.

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
ringingrelay (see theapplication circuit fig. 16).

L3234 - L3235

PLCC28

PINCONNECTION

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

V

BAT

V

CC

V

SS

T

T

stg

Battery Voltage -54 V
Positive Supply Voltage 5.5 V
Negative Supply Voltage -5.5 V
Max. Junction Temperature 150 °C

j

Storage Temperature -55 to +150 °C

OPERATINGRANGE

Symbol Parameter Min. Max. Unit

V

BAT

V

CC

V

SS

T

op

T

Note: Operating ranges definethose limits between which the functionality ofthe device is guaranteed.

Battery Voltage -52 -24 V
Positive Supply Voltage 4.75 5.25 V
Negative Supply Voltage -5.25 -4.75 V
Operating Temperature for L3235

Max Junction Operating Temperature 130 °C

j

L3235T

0

-40

70
85

°C
°C

11/26

L3234 - L3235

THERMAL DATA

Symbol Description Value Unit

R

th j-amb

PIN DESCRIPTION

Pin Name Description

1V
2 RING RING wire of 2 Wire LineInterface.
3 ZAC Non Inverting Inputof the AC Impedance Synthesis Circuit.
4 VREG Emitter Connection for the External Transistor.
5 AGND Analog/Digital Ground.
6 BGND Battery Ground. This is the Reference for the Battery Voltage (note 1).
7 CAC AC Current Feedback Input.
8 RPC External Protection Resistors AC TransmissionCompensation.
9 TX Four Wire Transmitting Amplifier Output.

10 ZB NonInverting OperationalInput Inserted in the Hybrid Circuit for 2W to 4W

11 ZA VRXOutput Buffer 2W to 4W Conversion.
12 RX High Impedance Four WireReceiving Input.
13 V
14 REF Voltage Reference Output; a Resistor Connected to this pin sets the Internal

15 V
16 IL Transversal Line Current Feedback Divided by 50.
17 VPOL Non Inverting OperationalInput to Implement DC Character.
18 BASE Driver for ExternalTransistor Base.
19 LIM Voltage Reference Output; a Resistor Connected to this Pin Sets the Value of

20 RNG Ringing Logic Input from Line Card Controller.
21 SBY Stand byLogic Input(SBY = 1 Set Line Current Limitation at 3mA).
22 PU Power u.p Logic Output forthe CodecFilter. (PU = 0 means CodecFilter

23 CS Ring Injector Enable for L3234 Output. (CS= 1 means L3234 Ringing

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 FilterInput.
28 TIP Tip Wire of 2 Wire Line Interface.

Note 1:

AGND and BGND pins must betied together at a low impedance point (e.g. at card connector level).

Thermal ResistanceJunction-ambient Max 80 °C/W

bat

Negative Battery Supply Input.

Conversion. The Network Connected from this Pinto Ground shall be a copy
of the Line Impedance.

CC

Positive 5V Supply Voltage.

Bias Current.

SS

Negative 5V Supply Voltage.

Line Current Limitation.

Activated)

Injection Enable).

12/26

L3235FUNCTIONAL DIAGRAM

L3234 - L3235

FUNCTIONAL DESCRIPTION

DIGITALINTERFACE
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/Ringingmodes.

2)RNGinput programs theringing ON/OFF acti­vationcondition for the L3234.

The L3235 digital interface has four outputpins :

1)OH provides the on hook/offhook 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
ringingmode 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 disconnec­tiontime 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 fixedthreshold. 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

(*)This status is latched and doesn’t change until RNG turn to 0

INPUT PIN LINE STATUS OUTPUT PIN

SBY RNG

0
0
0
0

0
0
0
0

1
1

0
0
0
0

1
1
1
1

0
1

0: ON HOOK
1: OFF HOOK

0
0
1
1

0
0
1
1

X
X

OPERATINGMODES
Stand-By(SBY = 1 and RNG = 0)

In Stand-By mode the L3235 limits the DC Loop
currentto 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 notbe activated.

This mode is useful in emergencycondition when
it is very important to limits the system power dis­sipation.

RingingMode (SBY= 0 and RNG = 1)
When ringing mode is selected ”CS” pin is set to

1 in order to activate the L3234 ringinginjector.
See L3234 for detailed description.
Ring trip is detectedby means of the same inter-

nal circuitry usedfor off-hookdetection.
An off-hook delay time lower than

1

⁄2F

RING

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 Controllermust
set the L3235 in active mode to remove the inter­nal latching of the ”CS” information.

0: NO GND KEY
1: GND KEY ON

0
1
0
1

0
1
0
1

X
X

OH GDK PU CS

1
0
0
0

1
0
0
0

1
1

1
0
1
0

1
0
1
0

1
1

1
0
0
0

0
0
0
0

1
0

0
0
0
0

1
0(*)
0(*)
0(*)

0

1

Active mode (SBY = 0 and CS1 = 0)
In Active mode the L3235 has the DC charac-

teristic show in Fig.13
The DC characteristicsof L3235 has two different

feedingconditions:

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 programlimit­ing currentvalues from 20 mAto 70 mA.

2) Voltagesource region (long loop).
The DC impedance of the L3235 is almost
equal to zero therefore the systemworks like
a voltage generator with in series the two ex­ternal protectionresistors 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
dissipationin 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.

14/26

L3234 - L3235

Figure13: DCcharacteristicin Active Mode withtwo different valuesoflimitingcurrent(30mAand70mA).

Figure14: Line current versus loop resistance with two differentvalues of limiting current (30mA and

70mA)

R

are the protection resistors

AC characteristic

A simplified AC model of the transmission circuits
is shown in figure 15.

Where :

Vrxis the received signal
V

is the transmitted signal

tx

V

is the AC transversal voltage at line terminations.

l

E

is the line open circuit AC voltage

g

Z

is the line impedance

l

p

Z

is the line impedance balancingnetwork

B

Z

is the SLIC impedance balancing network

A

Z

program the AC linetermination impedance

AC

R

used for external protection resistors insertion

PC

loss compensation

I

/50 is the AC transversal current divided by 50

l

CAC AC feedback current decoupling

15/26

L3234 - L3235

Figure15: SimplifiedAC Circuits

Two wire impedance

To calculate the impedance presented to the two
wire line by the SLIC including the protection re­sistorsR

V

rx

Il/50’= Il/50 (in first approximation)
Rp = 50Ω
Z

S=ZAC

ZACto make ZS=600Ω
Z

AC

Z

AC

Z

AC

Two wire to four wire gain (Txgain)
Let V

G

tx

V

tx

V

l

Example:Calculate Gtx making RPC=50⋅R
Gtx= 2 ⋅

As you can see the RPC resistor is providing the
compensation of the insertion loss introduced by
the two external protectionresistors R

Four wire to two wire gain (Rx gain)
Let Eg =0

G

rx

Example:
CalculateG

G

rx

and definedas ZSlet:

p

=0

/25 + 2R

P

=25•(ZS-2RP)
=25⋅(600- 100)
=12.5KΩ

=0

rx

V

tx

=

V

l

+ R

Z

=2⋅

AC

ZAC+ 50R

+ 50 ⋅ R

Z

AC

ZAC+ 50 ⋅ R

V

l

=

=

V

=

25 ⋅ (Z

25⋅ (Zl+ 2R

rx

makingZAC=25⋅(ZML-2⋅RP)

rx

50 ⋅ Z

+ 2R

l

P

PC

P

P

= 2

P

⋅ Z

50

P

l

− 2RP+ Z

l

)+ Z

ML

AC

P

.

P

)

2 ⋅ Z

Zl+ Z

l

ML

Grx=
In particular for ZS=Zl:Grx=1

Hybridfunction

To calculatedthe transhybridloss (Thl)let: Eg = 0
Thl =

= 4 (

Z
Z

B

+ ZA−

B

VT

x

=

VR

x

50 ⋅ ( 2 ⋅ R
50 ⋅ ( 2 ⋅ RP+ Zl)−2R

+ Zl)−2R

P

PC
AC

)

Example:
Calculating Thl making R
(ZSlic- 2 ⋅ R

Thl = 4 ⋅ (

In particular if

)

P

Z

B

Z

−

+ Z

B

Z

A

Z

Z

A

=

Z

Z

B

=50⋅RP,ZS=25⋅

S

Z

l

)

+ Z

l

ML

S

l

Thl = 0
From the above relation it is evident that if Z

equal to the Z

used in Thl test, the two ZA,ZBim-

l

S

pedancescan be tworesistorof the same value.

ACtransmissioncircuit stability

To ensure stability of the feedback loop shown in
blockdiagram form in figure 15 two capacitorsare
required. Figure 16 includes these capacitors Cc
and Ch.

AC - DCseparation

The high pass filter capacitor C

provides the

AC

separationbetweenDC circuitsand AC circuits.A
CAC value of 100mF will position the low end fre­quencyresponse 3dB break point at 7Hz,

fsp =

2π ⋅ 220Ω ⋅

1

C

AC

is

16/26

L3234 - L3235

Externalcomponents list forL3235

To set the SLIC into operation the followingparametershave to be defined:

- The AC SLICimpedance at line terminals ”Zs” to which the return loss measurementsis referred. It can
bereal (typ.600Ω)or complex.

- The equivalent AC impedanceof the line ”Zl”used for evaluationof the trans-hybridloss performance

(2/4 wire conversion).It is usually a compleximpedance.

- The value of the two protection resistorsRp inseries with the line termination.

Once, the above parameters are defined,it is possible to calculateall the external componentsusing the
followingtable. Thetypicalvalues has been obtained supposing:Zs = 600Ω; Zl =600Ω;Rp=50Ω

Name Suggested Value Function Formula

R

F

C

F

R

GF

C

GF

R

R

R

LIM

CR 4.7µF

R

P

R

T

C

AC

R

PC

Z

AC

C

C

Z

AS

R

AS

ZB 15K
C

H

C

TX

D1, D2 1N4007 Line Rectifier

Text (3) External Transistor P

;CV

CV

SS

DD

C

VB

Notes:

1) For proper operation Cf should be selected in order to verify the following conditions:
A)cf > 150nF
B)τ < 1/2 • f

f

RING

2) For protection purposes the RP resistor is usually splitted in twopart R

3) ex: BD140; MJE172; MJE350.... (SOT32 or SOT82 package availablealso for surface mount). For low power application (reduced battery

voltage) BCP53 (SOT223 surface mount package) can beused. Depending on application enviromentan heatsink could be necessary.

RING

: Ringing signal frequency

39KΩ

390nF

39KΩ

390nF

Delay Time
On-hook Off-hook

Delay Time
GK Detector

τ = 0.69 ⋅ C

τ = 0.69 ⋅ C

⋅ 39KΩ (1)

F

⋅ 39KΩ

GF

51KΩ Bias Set

8.4KΩ to 33KΩ Ext. Current Limit. Progr.

NegativeBattery

6.3 V 30%

Filter

R

LIM

C

AC

=

I

LIM

=

2π ⋅ 16KΩ ⋅

564

− 3mA
1

50 Protection Resistors 47 < RP< 100Ω (2)

1MΩ 20% TerminationResistor

100µF

6.3V 20%

DC/AC current feedbacksplitting

C

AC

=

2π ⋅ 220Ω ⋅

1

2500Ω 1% RPinsertionloss compensation RPC=25⋅(2RP)
12500Ω 1% 2W AC Impedance programmation ZAC=25⋅(ZS-2RP)
220pF 20% AC Feedback compensation

f1 = 300KHz C

=

C

2πf1 ⋅ 50R

12500Ω 1% Slic Impedance Balancing Net. ZAS=25⋅(ZS-2RP)

2500Ω 1% RAS = 25 ⋅ (2RP)

1% Line impedance Balancing Net. ZB=25⋅Zl

Ω

220pF 20% CCTransybrid loss Compensation

4.7µF 30% DC Decoupling Tx Output

C

H=CC

C

=

TX

> 2W, V

Diss

H

> 40, IC> 100mA

FE

V

< 0.8V@ 100mA

BE

Z

AC

⋅

Z

AS

1

6.28 ⋅ fp ⋅ Z

CEO

100nF ±5V supply filter

100nF/100V V

supply filter

BAT

and RP2, with RP1>30Ω.

P1

fp

f

sp

load

> 60V

1

P

17/26

L3234 - L3235

Figure16: TypicalAppicationCircuit Including L3234 andProtection

18/26

L3234 - L3235

ELECTRICAL CHARACTERISTICS (Test condition:refer to the test circuitof the fig. 17; VCC= 5V,

= -5V, V

V

SS

Note: Testing of all parameters is performed at 25°C. Characterization,as well as the designrules 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°Cto70°C) use L3234. If operations are required in the ex-
tended temperaturerange (-40°Cto85°C), use theL3234T.

Symbol Parameter Test Condition Min. Typ. Max. Unit Fig.

STAND-BY

V

ls

I

LCC

DC OPERATION

= -48V, T

bat

Output Voltage atTIP/RING

=25°C, unlessotherwisespecified)

amb

I

= 0 35.7 39 V

LINE

pins
Short Circuit Current Stand-by, SBY = 1 2 3 4 mA

V

lP

I

lim

I

lim

I

O

I

f

I

lgk

Gklim Ground Key Current

Output Voltage at TIP/RING
pins

Current Progr. I
Current Progr. 8.4KΩ <R

I

=0

LINE

I

= 50mA

LINE

Prog. = 70mA 63 70 77 mA

lim

< 33KΩ 20 70 mA

LIM

35.7

35.2

39
39

On-hook Threshold 5
Off-hook Threshold 10
GK Detector Threshold 10 17

RING to BGND 13 22 mA

Limitation

Gkov Ground Key Threshold

Gklim-Ilgk 1 mA

Overloap

I

max

Max. Output Current at

I

= 70mA 90 140 mA

lim

TIP/RING
IV
IV
IV

CC

SS
bat

Supply Current from V

Supply Current from V

Supply Current from V

CC
SS
bat

I

= 0 6.2 8 mA

line

Iline = 0 1.6 2.1 mA
Iline = 0 2.8 3.6 mA

AC OPERATION

Z

tx

Z

rx

R

l

Thl Trans Hybrid Loos f = 300 to 3400Hz 20 36 dB A2

G

s

G

sf

G

sl

G

r

G

rf

G

rl

Np4W Psoph. Noise atTx -69 -62 dBmp
Np2W Psoph. Noise at Line -75 -68 dBmp

S

vrr

S

vrr

L

tc

T

lc

(*) Selected parts L3235C

Sending Output Impedance pin 9 (Tx) 10 Ω

Receiving Input Impedance pin 12 (Rx) 1 MΩ

2W Return Loss f = 300 to 3400Hz 20 36 dB A1

Sending Gain f = 1020Hz Il= 20mA 5.82 6.02 6.22 dB A3

Flatness f = 300 to 3400Hz -0.2 0.2 dB

Linearity -20dB to 10dBm -0.2 0.2 dB

Receiving Gain f = 1020Hz Il= 20mA 0.2 0 0.2 dB A4

Flatness f = 300 to 3400Hz -0.2 0.2 dB

Linearity -20dBm to +4dBm -0.2 0.2 dB

Relative to V

Terminal versus Tx Terminal

Relative to Vccand V

versus Line Terminal versus

versus Line

bat

f = 1020Hz
V

= 100mVpp

S

ss

f = 1020Hz
V

= 100mVpp

S

-30

-24

-20

-14

Tx Terminal

L/T Conversion measured at

line Terminals

T/L Conversion Measured at

Line Terminals

f = 300 to 3400
I

= 20mA

line

f = 300 to 3400
I

= 20mA

line

49

53(*)
46(*) dB A7

V
V

dB
dB

dB
dB

dB
dB

A5

A6

19/26

L3234 - L3235

ELECTRICAL CHARACTERISTICS (continued)

Symbol Parameter Test Condition Min. Typ. Max. Unit Fig.

DIGITALSTATIC INTERFACE

V

il

V

ih

I

il

I

ih

V

ol

V

oh

Input Voltage at Logical ”0” Input SBY, CS1 0 0.8 V

Input Voltage at Logical ”1” Input SBY, CS1 2 5 V

Input Current at Logical ”0” Input SBY, CS1 10 µA

Input Current at Logical ”1” Input SBY, CS1 10 µA

Output Voltage at Logical ”0” I

Output Voltage at Logical ”1” I

Figure17: Test Circuit

out

I

out
out

I

out

= 1mA
=10µA

=10µA
= 1mA

4

2.7

0.5

0.4

V
V

V
V

20/26

L3234 - L3235

APPENDIXA

L3235 TEST CIRCUITS
Referring to the test circuit reported in fig 17 you

can find the proper configuration for the main
measurements.

FigureA1: 2W Return Loss

100µF

100µF

|Z

− Z|

R

L

= 20 log

ML

|ZML+ Z|

In particular:
A-B: Line terminals

C: Tx sending output on 4Wside
D: Rx receiving input on 4W Side

|2V

|

=20 log

|E

S

|

FigureA2: Trans-hybridLoss

V

T

HL

=20log

S

V

R

FigureA3: SendingGain

100µF

100µF

100µF

100µF

21/26

L3234 - L3235

TEST CIRCUITS(continued)
FigureA4: ReceivingGain

100µF

100µF

FigureA5: SVRRRelative to Battery Voltage VB

100µF

100µF

FigureA6: Longitudinalto TransversalConversion

22/26

FigureA7: Transversalto LongitudinalConversion

L3234 - L3235

APPENDIXB

LAYOUTSUGGESTIONS
Standard layout rules should be followed in order

to get thebest systemperformances:

1)Use always 100nF filtering capacitor close to
thesupply pins of each IC.

2) TheL3235biasresis tor(RR)shouldbeconnected

close to the correspondingpins ofL3235
(REFand AGND).

23/26

L3234 - L3235

HEPTAWATT (Surface Mount)PACKAGE MECHANICAL DATA

DIM.

MIN. TYP. MAX. MIN. TYP. MAX.

A 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 0.031

F1 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 0.307
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 0.198

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

V2 8°(max)

Dia 3.65 3.85 0.144 0.152

mm inch

24/26

PLCC28PACKAGE MECHANICAL DATA

L3234 - L3235

DIM.

MIN. TYP. 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 0.020

E 9.91 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

mm inch

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 informationnor forany infringement ofpatents or other rights of third parties which may result from itsuse. 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 withoutex­press writtenapproval of SGS-THOMSON Microelectronics.

 1995 SGS-THOMSON Microelectronics - All RightsReserved

SGS-THOMSON Microelectronics GROUP OF COMPANIES

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