March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

FEATURES

Internal supply

optimum current split-up
- low constant current (adjustable) in transmission IC
- nearly all line current available for listening-in
adjustable supply voltage

Loudspeaker amplifier

dynamic limiter providing low distortion and the
highest possible output power
SE or BTL drive for loudspeaker volume control by
potentiometer and/or logic inputs (e.g.
microcontroller drive)
fixed gain of 35 dB

Larsen level limiter

low sensitivity for own speech due to 3rd-order filter
and attack delay
adjustable voltage thresholds

Power down input

MUTE input

TEA1085/TEA1085A
- clickfree switching between listening-in mode and
standby mode

TEA1085
- toggle function
- start-up in standby condition

TEA1085A
- logic level input

GENERAL DESCRIPTION

The TEA1085 and TEA1085A are bipolar ICs which have
been designed for use in line-powered telephone sets and
provide a listening-in facility for the received line signal via
a loudspeaker. Nearly all the line current can be used for
powering the loudspeaker.
The circuits incorporate a supply circuit, loudspeaker
amplifier dynamic limiter, MUTE circuit, power-down
facility and logic inputs for gain setting. The devices also
incorporate a Larsen Level Limiter to reduce howling
effects.
The ICs are intended for use in conjunction with a
transmission circuit of the TEA1060 family.

ORDERING INFORMATION

Notes

1. SOT101-1; 1998 Jun 18.

2. SOT137-1; 1998 Jun 18.

EXTENDED TYPE

NUMBER

PACKAGE

PINS

PIN POSITION

MATERIAL

CODE

TEA1085/TEA1085A

DIL

plastic

SOT101B

(1)

TEA1085T/TEA1085AT

SO24

plastic

SOT137A

(2)

March

1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered

telephone sets

TEA1085; TEA1085A

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dbook, full pagewidth

MGR032

RECEIVING

AMPLIFIER

MUTE

PEAK AND

CURRENT

LIMITER

POWER

AMPLIFIER

START

CIRCUIT

I-STABILIZATION

LOGIC GAIN

CONTROL

LARSEN

LEVEL

LIMITER

SUPPLY

PREAMPLIFIER

LARSEN

LEVEL LIMITER

MUTE

LSI1

LSI2

DLC

SUP

SDC

SREF

QLA

DTI

TEA1060 (VEE)
TEA1060 (QR)

TEA1060

(MIC)

TEA1060

(MIC)

(2)

(1)

QLS2

QLS1

LAI

GSC1

GSC2

SIC 17

(1)

VBB 24

PD 19

VSS 1

VA 18

LAI

VBB

line

TEA1060

(LN)

THL2

LLC

THL1

DCA

(1)

VBB

(1)

TEA1085

TEA1085A

Fig.1 Block diagram.

(1) To TEA1060 (SLPE).

(2) See Fig.16.

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

PIN CONFIGURATION

SYMBOL PIN

DESCRIPTION

negative supply

SUP

positive supply

SDC

supply amplifier decoupling

SREF

supply reference input

LSI1

loudspeaker amplifier input 1

LSI2

loudspeaker amplifier input 2

GSC2

logic input 2 for gain select

GSC1

logic input 1 for gain select

LAI

Larsen limiter preamplifier inverting
input

LAI

Larsen limiter preamplifier
non-inverting input

QLA

Larsen limiter preamplifier output

LLC

Larsen limiter capacitor

THL2

Larsen limiter residual threshold level

THL1

Larsen limiter attack delay threshold
level

DTI

Larsen limiter detector input

DCA

Larsen limiter detector current
adjustment

SIC

Larsen limiter current stabilizer

voltage adjustment

power-down input

MUTE

MUTE input

QLS1

loudspeaker amplifier output 1

QLS2

loudspeaker amplifier output 2

DLC

dynamic limiter capacitor

stabilized supply decoupling

Fig.2 Pin configuration.

handbook, halfpage

VSS

SUP

SDC

SREF

LSI1

LSI2

GSC2

GSC1

LAI

QLA

LLC

VBB

DLC

QLS2

QLS1

MUTE

SIC

DCA

DTI

THL1

THL2

TEA1085

TEA1085A

MLA415

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

FUNCTIONAL DESCRIPTION

Figure 1 illustrates a block diagram of the
TEA1085/TEA1085A with external components and
connections to the transmission IC.
The TEA1085/TEA1085A are bipolar ICs which have been
designed for use in line-powered telephone sets and
provide a listening-in facility for the received line signal via
a loudspeaker. Nearly all the line current can be used for
powering the loudspeaker.
The loudspeaker amplifier consists of a preamplifier, to
amplify the earpiece signal from the transmission circuit
and, a double push-pull output stage to drive the
loudspeaker in the BTL (bridge tied load) or SE (single
ended) configuration. The gain of the preamplifier is
controlled by a dynamic limiter which prevents high
distortion of the loudspeaker signal. This is achieved by
preventing clipping of the loudspeaker signal, with respect
to the supply voltage, and at too low supply current. Two
logic inputs can be used to reduce the gain in 3 steps.
Because of acoustic feedback from the loudspeaker to the
microphone, howling signals (Larsen effect) can occur on
the telephone line and in the loudspeaker. When the
Larsen signal exceeds a voltage and time duration
threshold the Larsen level limiter (LLL) will reduce the

Larsen signal to a low level within a short period of time by
reducing the gain of the receiving preamplifier. This is
achieved by using the microphone signal as an input signal
which is processed in the LLL via a preamplifier and
3rd-order filter.
The MUTE input can be used to enable or disable the
loudspeaker amplifier.
The MUTE function of the TEA1085 has a toggle input to
permit the use of a simple push-button switch.
The MUTE function of the TEA1085A has a logic input to
operate with a microcontroller.
By activating the power-down input the current
consumption of the circuit will be reduced, this enables
pulse dialling or flash (register recall).
An internal start circuit ensures normal start-up of the
transmission IC and start-up of the listening-in IC in the
standby mode.
The TEA1085/TEA1085A are intended for use in
conjunction with a member of the TEA1060 family and
should be connected between LINE and SLPE of the
transmission IC. The transmission characteristics
(impedance, gain settings, for example) are not affected.
The interconnection between the two ICs is illustrated in
Fig.3.

Fig.3 Interconnection of the TEA1085/TEA1085A with the TEA1060.

handbook, full pagewidth

MGR033

TEA1060

VCC

VEE

SLPE

MIC

LAI

TEA1085

TEA1085A

SREF

SUP

VSS

LSI1

LSI2

QLS

LINE

to TEA1060

(SLPE)

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Supply; SUP, SREF, V

, V

and VA

The line current is divided into I

for the TEA1060 and I

SUP

for the TEA1085/TEA1085A.

The supply arrangement is illustrated in Fig.4.

Fig.4 Supply arrangement.

handbook, full pagewidth

MGR034

TEA1060

VCC

VEE

SLPE

TEA1085

TEA1085A

VSS

VBB

Iline

ITR

SUP

C20

ISUP

IBBO

IBIAS

ICC

R38

R20

VOLTAGE

STABILIZER

TR1

TR2

SREF

Vint

LINE

is constant: I

= V

int

/ R20; I

SUP

= I

line

Where:

A practical value for R20 is 150

. This value of resistance

produces a value for I

= 2 mA and I

SUP

= I

line

3 mA.

The TEA1085/TEA1085A stabilizes its own supply voltage
at V

. Transistor TR1 provides the supplies for the

internal circuits. TR2 is used to minimize the signal
distortion on the line by momentarily diverting the input
current to V

whenever the instantaneous value of the

voltage V

SUP

drops below the supply voltage V

. V

fixed to a typical value of 3.6 V but can be increased by
means of an external resistor (R38) connected between

int

is an internal temperature compensated
reference voltage with a typical value of
315 mV between SUP and SREF

R20

is a resistor between SUP and SREF

is the internal current consumption of the
TEA106X (

1 mA)

VA and V

or decreased by connecting this resistor

between VA and V

. The minimum level on V

restricted to 3.0 V; the level of the V

limiter is also

affected (see application report for further information).
The supply at V

is decoupled by a 470

F capacitor.

The DC voltage (V

SUP

) is determined by the

transmission IC (V

SLPE

); thus:

SUP

= V

SLPE

int

The minimum DC voltage that can be applied to this input
is V

BB(max)

0.4 V.

Where: V

BB(max)

is the worst case supply voltage (this

depends on the setting of R38, which is connected
between VA and V

The internal current consumption of the
TEA1085/TEA1085A (I

SUP0

) is typically 4.2 mA (where

SUP

= 4.5 V, MUTE off). Thus the current available

for powering the loudspeaker is I

SUP

SUP0

The current I

SUP0

consists of a bias current of

0.4 mA for

the circuitry connected to SUP and current I

BB0

3.8 mA

which is used for the circuitry connected to V

(see Fig.4).

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Supply amplifier stability (SDC) pin 3

To ensure stability of the TEA1085/TEA1085A, in
combination with a transmission IC of the TEA1060 family,
a 47 pF capacitor connected between SDC and SUP and
a 150

H coil connected between SUP and the positive

line terminal (Fig.16) is required.

Loudspeaker amplifier (LSI1/LSI2 and QLS1/QLS2)
pins 5/6, 21/22

The TEA1085/TEA1085A have symmetrical inputs at LSI1
and LSI2. The input signal is normally taken from the
earpiece output of the transmission circuit via a resistive
attenuator (see Fig.3). The amount of attenuation must be
chosen in accordance with the receive gain of the
transmission IC (which depends on the sensitivity of the
earpiece transducer). The maximum input signal level is
450 mV(RMS) at T

amb

The outputs QLS1 and QLS2 can be used for single ended
drive (SE) or bridge tied load drive (BTL). The output
stages have been optimized for use with a 50

loudspeaker (e.g. Philips type AD2071).
The gain of the amplifier is fixed to

35 dB for the SE drive

and

41 dB for the BTL drive (when the inputs for logic

control are left open-circuit or are connected to V

The volume control can be obtained by using a
potentiometer at the input and/or by the logic control
function.

Fig.5

Stabilized supply voltage as a function of
R38.

ndbook, halfpage

5.5

3.5

MGR035

3.9

4.3

4.7

5.1

R38 (k

)

VBB

(V)

VBB = 3.60 V

Logic gain control (GSC1 and GSC2) pins 7 and 8

The logic inputs GSC1 and GSC2 can be used to reduce
the gain of the loudspeaker amplifier by means of the logic
gain control function in 3 steps of 6 dB.

Table 1

Data for microcontroller drive of logic inputs

Where:

0 = connection to V

or left open-circuit

1 = applying a voltage

1.5 V

GSC2

GSC1

gain

(dB)

gain reduction

(dB)

28.7

6.3

22.2

12.2

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Dynamic limiter (DLC) pin 23

To prevent distortion of the signal at the loudspeaker
outputs the gain of the amplifier is reduced rapidly when:

the peaks of the signal at the loudspeaker outputs
exceed an internally determined threshold (voltage
limiter)

the DC current into SUP is insufficient (current limiter)

the voltage at V

decreases below an internally

determined threshold, typically 2.9 V (V

limiter)

The time in which the gain reduction is effected is the
'attack time'; this is very short in the first and third instance
and relatively long in the second instance. The circuit will
remain in the gain-reduced condition until the peaks of the
output signal remain below the threshold level. The gain
will then return to a nominal level after a time determined
by the capacitor connected to DLC (release time).

MUTE input (MUTE) pin 20; TEA1085A

This MUTE is provided with a logic input to operate with a
microcontroller for instance.
The loudspeaker amplifier is disabled when the MUTE
input is LOW (connected to V

or open input). A HIGH

level at the MUTE input enables the amplifier in the
listening-in mode.

MUTE input (MUTE) pin 20; TEA1085

The MUTE function is provided with a toggle input and is
designed to switch between the standby condition and the
listening-in condition on the rising edge of the input MUTE
signal (see Fig.6).
In the basic application the MUTE input must be LOW
(connected to V

). A simple push-button can be used to

operate the MUTE toggle (see Fig.7). Debouncing can be
realized by means of a small capacitor connected between
MUTE and V

An internal start circuit ensures that the circuit always
starts up in the standby condition.

Fig.6 Mute toggle function of the TEA1085.

handbook, full pagewidth

MGR036

LSI1

QLS1

MUTE

standby

listening-in

Fig.7 Mute switch alternatives with the TEA1085.

handbook, full pagewidth

MLA055

MUTE

VBB

10 k

(a) Break contact.

(b) Make contact.

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Power down input (PD) pin 19

During pulse dialling or register recall (timed loop break)
the telephone line is interrupted, thereby breaking the
supply to the transmission and listening-in circuits. The
capacitor connected to V

provides the supply for the

listening-in circuit during the supply breaks.
By making the PD input HIGH during the loop break the
requirement on the capacitor is eased and, consequently,
the internal (standby) current consumption I

BBO

(Fig.4) at

is reduced from 3.8 mA to 400

A typical. So that the

transmission circuit is not affected transistors TR1 and
TR2 are inhibited and the bias current is reduced from

0.4 mA to

A with V

SUP

= 4.5 V in the following

equation:

SUP(PD)

= I

BIAS(PD)

= (V

SUP

) / Ra

(where 4.2 V

SUP

3 V)

= the voltage drop across 2 internal diodes (

1.3 V)

Ra = an internal resistor of typical 60 k

Larsen limiter current stabilizer (SIC) pin 17

A current reference is set by resistor R36 between SIC and
V

. The preferred value is 120 k

. The internal reference

current is given by the following equation:

SIC

= 1.25 / R36; when R36 = 120 k

, I

SIC

= 10.5

Changing the value of R36 will affect the timing of the
Larsen level limiter system.

Larsen limiter preamplifier (LAI1/LAI2 and QLA) pins
9/10 and 11

This circuit amplifies the microphone signal to a level
suitable for the Larsen limiter detector. The gain is set by
external components (see Fig.8).
Normally the gain is set to the same level as the
microphone amplifier of the transmission circuit, this
ensures that the output signal level at output QLA is equal
to the line signal level.

The gain between QLA and the microphone input is given
by the following equation (the high-pass filter is not taken
into account):

pre

= V

QLA

/ V

= R29 / R26; in the basic application

R25 = R26 = 10 k

The gain can be adjusted between 30 dB (R29 = 316 k

)

and 52 dB (R29 = 4 M

). The impedance result of R28 and

R27 in parallel must be equal to R29
(e.g. R27 = R28 = 2

R29).

Fig.8 Larsen limiter preamplifier and voltage/current converter.

handbook, full pagewidth

MGR037

LAI

R25

R26

R29

C22

C23

DTI

DCA

IDCA

THL1

THL2

R27

QLA

C24

R30

R33

R32

C25

R31

R35

R34

VQLA

VBB

VSS

VBB

R28

LARSEN

DETECTOR

LLC

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Larsen limiter detector (DTI and DCA) pins 15 and 16

The QLA output signal is AC coupled to the detector input
DTI. DTI is biased by potential divider R30 and R31. The
voltage applied to DTI of the Larsen level limiter is
converted into a current for further processing in this
circuit. Current adjustment is achieved using the network
connected between DCA and V

(see Fig.8).

The equation for DC current is:

The equation for AC current is:

In the basic application:

R30 = 100 k

, R31 = 220 k

, R33 = 500

, R32 = 100 k

and C25 = 330 nF

This results in I

DCA

= 11

A and the equation:

High-pass filter

A third order high-pass filter is created between the
microphone input voltage and the current flowing into
DCA. The cut-off frequencies (see Fig.9) of the three
sections are:

Where: R25 = R26 and C22 = C23

The filter reduces the sensitivity of the system to own
speech.
Normal speech is in the frequency range 300 Hz to
3400 Hz, however, the Larsen signal normally occurs at a
frequency

3 kHz.

With the component values as used in the basic
application (see Fig.16); f1 = 500 Hz, f2 = 1 kHz and
f3 = 3 kHz

DCA

R30

R31

-----------------------------

R32

R33

-----------------------------

DCA

DTI

R33

------------

for f >

1
2

---

R33 C25

DCA

DTI

------------

2 (mA/V)

C24

-----------------------------

where R

R30

R31

R30

R31

-----------------------------

R33C24

------------------------------

R26C23

------------------------------

1/(2

R25C22

)

Where:

Larsen limiter capacitor (LLC) pin 12

A 1

F capacitor (C26) is connected externally between

and LLC to determine the attack and release timing of

the Larsen level limiter in the listen-in and Larsen mode.
The timing is also dependent on the value of the resistor
connected between SIC and V

Larsen level limiter threshold (THL1 and THL2) pins
13 and 14

When the signal at DTI exceeds the first threshold level the
capacitor connected to LLC will start to discharge. The first
threshold level is determined by the value of the resistor,
R35, connected to THL1 and V

. The amount of

discharge of C26 depends on how much the level of the
signal at DTI exceeds the first threshold level (for normal
speech the discharge is small).
The Larsen effect is generally defined as a signal level of

100 mV(RMS), on line, for a period of more than 100 ms.

The Larsen signal must be reduced to a low level within
200 ms. For Larsen signal levels (f

f3 in Fig.9) of

100 mV(RMS) at DTI and, with the component values of

Fig.16, the system will switch from the listen-in mode to the
Larsen mode in a time period of 100 ms to 200 ms;
consequently, the initial Larsen effect will last only for a
short period of time.

Fig.9 Third-order high-pass filter.

handbook, halfpage

MGR038

20 log

(dB)

20 log f

12 dB per octave

6 dB per octave

18 dB per octave

speech

Larsen

DCA

-----------

pre

R33

-----------

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

This reaction time is the 'attack delay time' and ensures
minimum sensitivity of the system for own speech.

The first threshold level at DTI is determined by the
equation:

Where: I

DCA

= the DC current into DCA

With the component values given in Fig.16, I

DCA

= 11

thus V

DTI1

= 18.8 mV.

Listen-in mode

During normal speech the discharge of the capacitor
connected to LLC is not sufficient to reach the threshold
level whereby the system switches to the Larsen mode.
This is because normal speech is not continuous, the
discharge of C26 is slow (attack delay) and the charge is
fast.
The slope of V

LLC

during charge is given in the equation:

With C26 = 1

F and R36 = 120 k

this results in

= 10 V/s.

Discharge of the capacitor at LLC occurs when the signal
at DTI exceeds V

DTI1

, thus for a continuous signal at DTI

the attack delay time t

(see Fig.10) is determined by the

equation:

Where k = t

/ T

The duty cycle is determined by the time in which the first
threshold level (V

DTI1

) is exceeded by the signal level at

DTI (see Fig.11) thus for large signals; k

0.5.

With the component values given in Fig.16; k

0.457 for

signals

100 mV(RMS).

Consequently 120 ms

160 ms, for

DTI

100 mV(RMS)

DTI1

1.25
R25

-----------

DCA

------------

R33

if f > f3 in Fig.9

(

)

LLC

-----------------

1.25

C26

R36

-----------------------------

V s

(

)

C26

R36

(

)

--------------------------------------

Larsen mode

After the 'attack delay time' the circuit switches from the
listen-in mode to the Larsen mode. The gain of the
loudspeaker amplifier is reduced quickly to a value
(t

LAa

= Larsen attack time, see Fig.10) whereby the

residual Larsen signal is determined by a second
threshold level. This level can be set by resistor R34
connected between THL2 and V

. The second threshold

level must always be selected at a lower level than the first
threshold level thus R34

R35.

The time taken to effect gain reduction is very short. In the
Larsen mode the circuit acts as a dynamic limiter with peak
detector and regulates the gain so that the signal level at
DTI is determined by the second threshold level V

DTI2

The second threshold level at DTI is determined by the
equation:

Where: I

DCA

= the DC current into DCA

With the component values given in Fig.16,
V

DTI2

= 6.9 mV.

The charge current in the Larsen mode is reduced to half
the charge current in the listen-in mode.

The slope of V

LLC

during charge (see Fig.10) is given in the

equation:

Where: C26 = 1

F and R36 = 100 k

, S

= 5 V/s

When the Larsen effect stops (total open-loop gain

1) the

gain of the loudspeaker amplifier will return to its normal
value in a time period known as the 'Larsen release time'
(t

LAr

). This time period is determined by capacitor C26

connected to LLC and resistor R36 connected to SIC.

Where: C26 = 1

F and R36 = 120 k

, t

LAr

= 250 ms

In practice the choice of the threshold levels (determined
by R35 and R34) depends on the sensitivity of the
microphone and loudspeaker, the send and receive gains,
sidetone suppression and the acoustical properties which
are determined by the cabinet of the telephone set.

DTI2

1.25
R34

-----------

DCA

------------

R33

if f > f3 in Fig.9

(

)

LLC

-----------------

1.25

C26

R34

--------------------------------------

V s

(

)

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

LIMITING VALUES

In accordance with the Absolute Maximum System (IEC 134)

THERMAL RESISTANCE

Note

1. Device mounted on a glass epoxy board 40.1

19.1

1.5 mm.

SYMBOL

PARAMETER

CONDITIONS

MIN.

MAX.

UNIT

SUP

positive supply voltage

continuous

during switch-on or line interruption

13.2

repetitive supply voltage from 1 ms to 5 s

with 12

current

limiting resistor in
series with supply

SREF

supply reference voltage

0.5

SUP

0.5

voltage on all other pins

0.5

SUP

supply current

TEA1085/TEA1085A

see Fig.12

120

TEA1085T/TEA1085AT

see Fig.13

120

tot

total power dissipation

amb

= 75

= 125

TEA1085/TEA1085A

TEA1085T/TEA1085AT

666

amb

operating ambient temperature range

stg

storage temperature range

125

junction temperature

125

SYMBOL

PARAMETER

CONDITIONS

THERMAL

RESISTANCE

th j-a

from junction to ambient in free air

TEA1085/TEA1085A

50 K/W

TEA1085T/TEA1085AT

note 1

75 K/W

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

CHARACTERISTICS

SREF

= 4.2 V; V

= 0 V; I

SUP

= 15 mA; V

SUP

= 0 V(RMS); f = 800 Hz; T

amb

= 25

C; PD = LOW; MUTE (TEA1085) =

OFF (listening-in mode); MUTE (TEA1085A) = HIGH (listening-in mode); GSC1 = GSC2 = LOW; 50

loudspeaker;

no R38; test circuit Fig.14; unless otherwise specified

SYMBOL

PARAMETER

CONDITIONS

MIN.

TYP.

MAX.

UNIT

Supplies

SUP

minimum DC input voltage

0.7

SUP-SREF

internal reference voltage

275

315

355

stabilized supply voltage

no R38; I

SUP

= 15 mA

3.4

3.6

3.8

variation from
I

SUP

= 15 to 120 mA

R38 = 39.2 k

between

pins V

and VA;

SREF

= 5.2 V;

SUP

= 15 mA

4.2

4.45

4.7

variation with temperature

no R38; I

SUP

= 15 mA

tbf

0.2

tbf

SUP

minimum operating current

4.2

5.5

THD

distortion of AC signal on SUP V

SUP(RMS)

= 1 V

0.3

no(RMS)

noise between SUP and V

dBmp

current consumption in
power-down condition

PD = HIGH

SUP

= 4.5 V

= 3.6 V

400

550

Loudspeaker amplifier inputs LSI1 and LSI2

input impedance

single ended

7.5

9.5

11.5

differential

voltage gain with 50

load

SUP

= 15 mA;

= 1.8 mV(RMS)

single ended

BTL output

39.9

40.9

41.9

variation with signal level

SUP

= 50 mA;

= 1.8 mV(RMS) and

14 mV(RMS)

single ended

0.1

0.4

BTL output

0.2

0.6

variation with frequency
referred to 1 kHz

f = 300 Hz and 3400 Hz;
V

= 1.8 mV(RMS)

single ended

0.1

BTL output

0.1

variation with temperature
referred to 25

amb

25 to

single ended

0.4

BTL output

0.5

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Loudspeaker outputs QLS1 and QLS2

o(p-p)

output voltage (peak-to-peak
value)

= 22 mV(RMS)

single ended

SUP

= 9 mA; note 1

1.2

1.45

SUP

= 17 mA; note 2

2.5

2.9

bridge tied load

SUP

= 23.5 mA; note 2

2.5

2.9

SUP

= 32 mA; note 3

3.5

4.0

THD

total harmonic distortion

= 22 mV(RMS)

single ended

SUP

= 9 mA

0.4

SUP

= 17 mA

0.7

bridge tied load

SUP

= 23.5 mA

0.4

o(p-p)

output voltage (peak-to-peak
value)

= 22 mV(RMS)

single ended

SUP

= 17 mA;

SUP

= 1 V(RMS)

1.75

2.15

Dynamic limiter

THD

total harmonic distortion

= 22 mV(RMS)

10 dB

single ended

SUP

= 9 mA

0.5

SUP

= 17 mA

1.2

bridge tied load

SUP

= 23.5 mA

0.6

att

dynamic behaviour of limiter
attack time; V

jumps from

10 mV(RMS) to 65 mV(RMS)

single ended load

voltage limiter

SUP

= 17 mA

current limiter

SUP

= 12 mA

500

tbf

limiter

SUP

= 9 mA

rel

release time; V

jumps from

65 mV(RMS) to 10 mV(RMS)

SUP

= 17 mA

tbf

BBO

threshold V

limiter below

which gain reduction starts

SUP

= 9 mA

tbf

2.95

tbf

no(RMS)

noise output voltage

1 k

between inputs

LSI1, LSI2;
psophometrically
weighted (P53 curve)

single ended

170

bridge tied load

350

Logic gain control

reduction of voltage gain

= 1.8 mV(RMS)

GSC2 = 0, GSC1 = 1

5.8

6.3

6.8

GSC2 = 1, GSC1 = 0

11.7

12.2

12.7

GSC2 = 1, GSC1 = 1

SYMBOL

PARAMETER

CONDITIONS

MIN.

TYP.

MAX.

UNIT

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Larsen limiter preamplifier

operational amplifier

open-loop gain

1st pole

120

2nd pole

3.3

MHz

unity gain bandwidth

MHz

voltage gain

f = 3 kHz;
R26 = 10 k

;

R29 = 4 M

gain adjustment range

Larsen limiter detector

voltage to current convertor

DCA

-V

DTI

DC offset voltage

DTI

= 1 V

voltage gain from DTI to DCA

DTI

= 100 mV(RMS);

f = 3 kHz

tbf

0.8

tbf

THL1

DC voltage at THL1

R35 = 51 k

1.8

1.25

1.33

THL2

DC voltage at THL2

R34 = 100 k

1.8

1.25

1.33

dynamic behaviour with a
burst at DTI

f = 3 kHz; see Fig.15

LIr

listen-in release time

see Fig.15(a)

tbf

attack delay time

see Fig.15(b)

DTI

jumps from

0 to 100 mV (RMS value)

160

200

DTI

jumps from

0 to 1 V (RMS value)

100

120

LAa

Larsen attack time

see Fig.15(b);
V

DTI

= 100 mV(RMS)

tbf

LAr

Larsen release time

see Fig.15(b)

DTI

jumps from

100 mV to 0 mV (RMS
value)

tbf

250

tbf

LLC

DC voltage at LLC

DTI

= 0 V

1.75

1.9

2.0

LLC

reduction of V

LLC

to attack

Larsen mode

0.59

0.63

0.68

gain reduction

LLC

= 0.7 V

tbf

SYMBOL

PARAMETER

CONDITIONS

MIN.

TYP.

MAX.

UNIT

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Notes

1. Typical output power is 5 mW into 50

2. Typical output power is 20 mW into 50

3. Typical output power is 40 mW into 50

MUTE input; TEA1085

(toggle function, positive edge
triggered set-reset flip-flop)

LOW level input voltage

0.3

HIGH level input voltage

1.5

0.4

MUTE

input current

MUTE = LOW

minimum input pulse width

minimum pulse repetition time

BB(MUTE)

supply voltage below which
MUTE toggle is reset

tbf

reduction of gain from LSI1,
LSI2 to QLS1, QLS2

MUTE = ON

100

MUTE input; TEA1085A

LOW level input voltage

0.3

HIGH level input voltage

1.5

0.4

MUTE

input current

MUTE = HIGH

reduction of gain from LSI1,
LSI2 to QLS1, QLS2

MUTE = HIGH

100

Power down input

LOW level input voltage

0.3

HIGH level input voltage

1.5

0.4

input current

PD = HIGH

2.3

2.8

Logic inputs GSC1 and GSC2

LOW level input voltage

0.3

HIGH level input voltage

1.5

0.4

GSC

input current

GSC = HIGH

SYMBOL

PARAMETER

CONDITIONS

MIN.

TYP.

MAX.

UNIT

March

1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered

telephone sets

TEA1085; TEA1085A

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agewidth

MGR043

C20

R20

C21

R35

R28

(1)

C28

(1)

R36

(1)

R34

R33

R29

R26

R31

R30

R32

(1)

C26

C23

C24

C27

C25

(1)

VBB

R27

R25

C22

VBB

C31

(1)

for

TEA1085

for

TEA1085A

TEA1060

TEA1085

TEA1085A

RL
50

IIN

ISUP

Iline

VLSI

VDTI

ILN

ICC

Fig.14 Test circuit.

The DC current is divided as follows:

The pins not shown in the TEA1060 are left open. An impedance in series with pin SUP (e.g. an ammeter)
should be avoided as it interferes with the value of I

SUP

SREF

R20

-------------------------------

SUP

SREF

R20

-------------------------------

(1) To TEA1060 (SLPE)

March

1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered

telephone sets

TEA1085; TEA1085A

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APPLICA

TION INFORMA

TION

handbook, full pagewidth

MLA039

DIALLER

TONE

LINE

interrupt

C11

C29

C30

C32

C20

R38

R24

RV20

R20

C21

R35

R28

(1)

C28

(1)

R36

(1)

R34

R33

R29

R26

R31

R30

R32

(1)

C26

C24

C23

C27

C25

(1)

VBB

R27

R25

C22

VBB

C31

(1)

for

TEA1085

for
TEA1085A

to TEA1060
pins 7 and 8

TEA1060

TEA1085

TEA1085A

Fig.16 Basic application of TEA1085/TEA1085A and TEA1060.

(1) To TEA1060 (SLPE).

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

The basic application circuit of the TEA1085/TEA1085A is illustrated in Fig.16. Only the most important components of
the TEA1060 part are shown, other components and their values are given in the TEA1060 Data sheet.
The supply pin (V

) of the TEA1085/TEA1085A can also be used to supply peripheral circuits (e.g. microcontrollers,

diallers etc.). Further information will be published in the TEA1085 application report.

Table 3

Component values in application circuit Fig.16

Note

1. Value depends on the gain setting of the transmission circuit.

COMPONENT

CONDITION

VALUE

UNIT

Resistor

R20

150

R24

note 1

R25

R26

R27

note 1

3.3

R28

note 1

3.3

R29

note 1

1.65

R30

100

R31

220

R32

100

R33

500

R34

100

R35

R36

120

RV20

note 1

Capacitor

C11

4.7

C20

470

C21

C22

4.7

C23

4.7

C24

4.7

C25

330

C26

C27

C28

330

C29

220

C30

220

C31

TEA1085 only 10

Coil

150

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

SOLDERING

Introduction

There is no soldering method that is ideal for all IC
packages. Wave soldering is often preferred when
through-hole and surface mounted components are mixed
on one printed-circuit board. However, wave soldering is
not always suitable for surface mounted ICs, or for
printed-circuits with high population densities. In these
situations reflow soldering is often used.

This text gives a very brief insight to a complex technology.
A more in-depth account of soldering ICs can be found in
our

"Data Handbook IC26; Integrated Circuit Packages"

(order code 9398 652 90011).

DIP

OLDERING BY DIPPING OR BY WAVE

The maximum permissible temperature of the solder is
260

C; solder at this temperature must not be in contact

with the joint for more than 5 seconds. The total contact
time of successive solder waves must not exceed
5 seconds.

The device may be mounted up to the seating plane, but
the temperature of the plastic body must not exceed the
specified maximum storage temperature (T

stg max

). If the

printed-circuit board has been pre-heated, forced cooling
may be necessary immediately after soldering to keep the
temperature within the permissible limit.

EPAIRING SOLDERED JOINTS

Apply a low voltage soldering iron (less than 24 V) to the
lead(s) of the package, below the seating plane or not
more than 2 mm above it. If the temperature of the
soldering iron bit is less than 300

C it may remain in

contact for up to 10 seconds. If the bit temperature is
between 300 and 400

C, contact may be up to 5 seconds.

EFLOW SOLDERING

Reflow soldering techniques are suitable for all SO
packages.

Reflow soldering requires solder paste (a suspension of
fine solder particles, flux and binding agent) to be applied
to the printed-circuit board by screen printing, stencilling or
pressure-syringe dispensing before package placement.

Several techniques exist for reflowing; for example,
thermal conduction by heated belt. Dwell times vary
between 50 and 300 seconds depending on heating
method. Typical reflow temperatures range from
215 to 250

Preheating is necessary to dry the paste and evaporate
the binding agent. Preheating duration: 45 minutes at
45

AVE SOLDERING

Wave soldering techniques can be used for all SO
packages if the following conditions are observed:

A double-wave (a turbulent wave with high upward
pressure followed by a smooth laminar wave) soldering
technique should be used.

The longitudinal axis of the package footprint must be
parallel to the solder flow.

The package footprint must incorporate solder thieves at
the downstream end.

During placement and before soldering, the package must
be fixed with a droplet of adhesive. The adhesive can be
applied by screen printing, pin transfer or syringe
dispensing. The package can be soldered after the
adhesive is cured.

Maximum permissible solder temperature is 260

C, and

maximum duration of package immersion in solder is
10 seconds, if cooled to less than 150

C within

6 seconds. Typical dwell time is 4 seconds at 250

A mildly-activated flux will eliminate the need for removal
of corrosive residues in most applications.

EPAIRING SOLDERED JOINTS

Fix the component by first soldering two diagonally-
opposite end leads. Use only a low voltage soldering iron
(less than 24 V) applied to the flat part of the lead. Contact
time must be limited to 10 seconds at up to 300

C. When

using a dedicated tool, all other leads can be soldered in
one operation within 2 to 5 seconds between
270 and 320

March 1992

Philips Semiconductors

Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

DEFINITIONS

LIFE SUPPORT APPLICATIONS

These products are not designed for use in life support appliances, devices, or systems where malfunction of these
products can reasonably be expected to result in personal injury. Philips customers using or selling these products for
use in such applications do so at their own risk and agree to fully indemnify Philips for any damages resulting from such
improper use or sale.

Data sheet status

Objective specification

This data sheet contains target or goal specifications for product development.

Preliminary specification

This data sheet contains preliminary data; supplementary data may be published later.

Product specification

This data sheet contains final product specifications.

Limiting values

Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or
more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation
of the device at these or at any other conditions above those given in the Characteristics sections of the specification
is not implied. Exposure to limiting values for extended periods may affect device reliability.

Application information

Where application information is given, it is advisory and does not form part of the specification.

Internet: http://www.semiconductors.philips.com

Philips Semiconductors a worldwide company

SCA60

All rights are reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner.

The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed
without notice. No liability will be accepted by the publisher for any consequence of its use. Publication thereof does not convey nor imply any license
under patent- or other industrial or intellectual property rights.

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Printed in The Netherlands

415102/00/02/pp32

Date of release: March 1992

Document order number:

9397 750 nnnnn

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ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: TEA1085T