Datasheet TEA1085T, TEA1085AT, TEA1085A, TEA1085 Datasheet (Philips)

INTEGRATED CIRCUITS

DATA SH EET

TEA1085; TEA1085A

Listening-in circuit for line-powered
telephone sets

Preliminary specification
File under Integrated Circuits, IC03A

March 1992

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

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

TEA1085; TEA1085A

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

EXTENDED TYPE

NUMBER

TEA1085/TEA1085A 24 DIL plastic SOT101B
TEA1085T/TEA1085AT 24 SO24 plastic SOT137A

Notes

1. SOT101-1; 1998 Jun 18.

2. SOT137-1; 1998 Jun 18.

March 1992 2

PINS PIN POSITION MATERIAL CODE

PACKAGE

(1)
(2)

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

TEA1085; TEA1085A

telephone sets

QUICK REFERENCE DATA

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

I

SUP

V

BB

I

SUP

G

v

∆G

v

I

SUP

t

ad(RMS)

V

DTI(RMS)

G

v

T

amb

input current range 4 − 120 mA
stabilized supply voltage − 3.6 − V
current consumption PD = HIGH − 55 −µA
voltage gain loudspeaker amplifier

SE − 35 − dB
BTL − 41 − dB

maximum gain reduction with logic

− 18 − dB

inputs (3 steps)
minimum input current

P

= 20 mW typ.

OUT

− 15 17 mA

into 50 Ω SE
P

= 40 mW typ.

OUT

−−32 mA

into 50 Ω BTL

Larsen limiter attack delay time V

DTI

100 − 200 ms

jumps from 0 to ≥ 100 mV (RMS value)
Larsen limiter threshold level Larsen mode − 7 − mV
Larsen limiter preamplifier gain setting

30 − 52 dB

range
operating ambient temperature range −25 −+75 °C

March 1992 3

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March 1992 4

dbook, full pagewidth

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

telephone sets

V

line

TEA1060

(LN)

V

1

SS

V

24

BB

19

PD

18

VA

(1)

V

BB

SREF
4

SUPPLY

4

SUP3SDC
2

PD

(1)

THL1
14

BB

THL212LLC
13

LARSEN

LEVEL

LIMITER

DCA
16

DTI
15

(1)

QLA
11

PREAMPLIFIER
LEVEL LIMITER

LARSEN

LAI−

109LAI+

TEA1060

(MIC)

TEA1060

(MIC)

V

BB

TEA1085

GSC1 8
GSC2 7

(1)

SIC 17

I-STABILIZATION

LOGIC GAIN

CONTROL

PEAK AND
CURRENT

LIMITER

2
2
2

RECEIVING

AMPLIFIER

MUTE

TEA1085A

POWER

AMPLIFIER

START

CIRCUIT

QLS1

2221QLS2

TEA1085; TEA1085A

(1) To TEA1060 (SLPE).
(2) See Fig.16.

23
DLC

(1)

20 5
MUTE LSI1 LSI2

(2)

6

MGR032

TEA1060 (VEE)
TEA1060 (QR)

(1)

Fig.1 Block diagram.

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

PIN CONFIGURATION

SYMBOL PIN DESCRIPTION

V

SS

SUP 2 positive supply
SDC 3 supply amplifier decoupling
SREF 4 supply reference input
LSI1 5 loudspeaker amplifier input 1
LSI2 6 loudspeaker amplifier input 2
GSC2 7 logic input 2 for gain select
GSC1 8 logic input 1 for gain select
LAI− 9 Larsen limiter preamplifier inverting

LAI+ 10 Larsen limiter preamplifier

QLA 11 Larsen limiter preamplifier output
LLC 12 Larsen limiter capacitor
THL2 13 Larsen limiter residual threshold level
THL1 14 Larsen limiter attack delay threshold

DTI 15 Larsen limiter detector input
DCA 16 Larsen limiter detector current

SIC 17 Larsen limiter current stabilizer
VA 18 V
PD 19 power-down input
MUTE 20 MUTE input
QLS1 21 loudspeaker amplifier output 1
QLS2 22 loudspeaker amplifier output 2
DLC 23 dynamic limiter capacitor
V

BB

1 negative supply

input

non-inverting input

level

adjustment

voltage adjustment

BB

24 stabilized supply decoupling

handbook, halfpage

TEA1085; TEA1085A

V

1

SS

SUP

2

SDC

3

SREF

4

LSI1

5

LSI2

6

TEA1085

GSC2
GSC1

LAI−
LAI+

QLA

LLC

TEA1085A

7
8

9
10
11
12

MLA415

Fig.2 Pin configuration.

V

24

BB

DLC

23

QLS2

22

QLS1

21

MUTE

20
19

PD
VA

18
17

SIC
DCA

16

DTI

15

THL1

14

THL2

13

March 1992 5

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

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

TEA1085; TEA1085A

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.

handbook, full pagewidth

LINE

V

CC

TEA1060

V

EE SLPE

LN

MIC+

MIC−

QR

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

March 1992 6

SREF SUP

LAI+

TEA1085

TEA1085A

LAI−

LSI1 LSI2

MGR033

QLS

V

SS

to TEA1060

(SLPE)

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

Supply; SUP, SREF, VBB, VSSand VA

The line current is divided into I
The supply arrangement is illustrated in Fig.4.

handbook, full pagewidth

LINE

I

line

I

CC

V

V

for the TEA1060 and I

TR

I

I

R1

CC

TEA1060

EE SLPE

TR

R20

LN

SUP

SUP

V

SREF

TEA1085

TEA1085A

for the TEA1085/TEA1085A.

SUP

TR1

int

I

TR2

BIAS

V

TEA1085; TEA1085A

V

BB

I

BBO

VOLTAGE

STABILIZER

SS

VA

R38

C20

R9

ITR is constant: ITR=V

/ R20; I

int

SUP=Iline

− ICC− I

TR

Fig.4 Supply arrangement.

Where:

V

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
I

CC

is the internal current consumption of the

TEA106X (≈ 1 mA)

A practical value for R20 is 150 Ω. This value of resistance
produces a value for I

= 2 mA and I

TR

SUP

= I

line

− 3 mA.

The TEA1085/TEA1085A stabilizes its own supply voltage
at VBB. 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 VSS whenever the instantaneous value of the
voltage V

drops below the supply voltage VBB. VBB is

SUP

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

MGR034

VA and VSS or decreased by connecting this resistor
between VA and VBB. The minimum level on VBB is
restricted to 3.0 V; the level of the VBB limiter is also
affected (see application report for further information).
The supply at VBB is decoupled by a 470 µF capacitor.

The DC voltage (V
transmission IC (V
V

− VSS = V

SUP

LN−SLPE

− VSS) is determined by the

SUP

+ V

); thus:

.

int

LN−SLPE

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

Where: V

BB(max)

+ 0.4 V.

is the worst case supply voltage (this

BB(max)

depends on the setting of R38, which is connected
between VA and VSS).

The internal current consumption of the
TEA1085/TEA1085A (I
V

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

SUP

for powering the loudspeaker is I
The current I

consists of a bias current of ≈ 0.4 mA for

SUP0

the circuitry connected to SUP and current I

) is typically 4.2 mA (where

SUP0

− I

SUP0

.

BB0

SUP

of≈ 3.8 mA

which is used for the circuitry connected to VBB(see Fig.4).

March 1992 7

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

5.5

dbook, halfpage

V

BB

(V)

5.1

4.7

4.3

3.9

3.5
10 10

2

R38 (kΩ)

MGR035

VBB = 3.60 V

3

10

TEA1085; TEA1085A

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

GSC2 GSC1

gain

(dB)

0 0 35 0
0 1 28.7 6.3
1 0 22.2 12.2
1 1 17 18

Where:

0 = connection to VSS or left open-circuit
1 = applying a voltage ≥ VSS+ 1.5 V

gain reduction

(dB)

Fig.5 Stabilized supply voltage as a function of

R38.

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 µH 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

= +25 °C.

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

March 1992 8

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

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 VBB decreases below an internally

determined threshold, typically 2.9 V (VBB 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).

TEA1085; TEA1085A

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 VSS 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
operate the MUTE toggle (see Fig.7). Debouncing can be
realized by means of a small capacitor connected between
MUTE and VSS.
An internal start circuit ensures that the circuit always
starts up in the standby condition.

). A simple push-button can be used to

SS

handbook, full pagewidth

handbook, full pagewidth

LSI1

MUTE

QLS1

standby standbylistening-in

Fig.6 Mute toggle function of the TEA1085.

MUTE MUTE

(a) Break contact. (b) Make contact.

10 kΩ

MGR036

V

BB

MLA055

Fig.7 Mute switch alternatives with the TEA1085.

March 1992 9

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

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 VBB 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
VBB is reduced from 3.8 mA to 400 µA 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 ≈ 55 µA with V

= 4.5 V in the following

SUP

equation:
I
(where 4.2 V < V

SUP(PD)

= I

BIAS(PD)

= (V

< VBB+ 3 V)

SUP

− 2Vd) / Ra

SUP

2Vd = the voltage drop across 2 internal diodes (≈ 1.3 V)
Ra = an internal resistor of typical 60 kΩ

(Fig.4) at

BBO

TEA1085; TEA1085A

I

= 1.25 / R36; when R36 = 120 kΩ, I

SIC

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):

A

pre

= V

/ VM = R29 / R26; in the basic application

QLA

R25 = R26 = 10 kΩ

= 10.5 µA

SIC

Larsen limiter current stabilizer (SIC) pin 17

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

. The preferred value is 120 kΩ. The internal reference

SS

current is given by the following equation:

QLA

V

V

QLA

handbook, full pagewidth

R29

C23

R26

V

M

R25

C22

LAI−

LAI+

R28

R27

−

+

V

BB

The gain can be adjusted between 30 dB (R29 = 316 kΩ)
and 52 dB (R29 = 4 MΩ). The impedance result of R28 and
R27 in parallel must be equal to R29
(e.g. R27 = R28 = 2 × R29).

BB

R32C25

I

R30

DTI

−

+

LLC

C24

V

SS

R31

DCA

LARSEN

DETECTOR

THL1 THL2

R33

DCA

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

March 1992 10

R35 R34

MGR037

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

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 VBB(see Fig.8).

The equation for DC current is:

R30

I

DCA

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

R30 R31+

V

BB

The equation for AC current is:

i

DCA

V

DTI

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

R33

forf>

1

-- -

π R33 C25=

2

In the basic application:
R30 = 100 kΩ, R31 = 220 kΩ, R33 = 500 Ω, R32 = 100 kΩ

and C25 = 330 nF
This results in I

i

DCA

----------- - 2 (mA/V)=
V

DTI

= 11 µA and the equation:

DCA

1

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

××=

R32 R33+

handbook, halfpage

20 log

g

(dB)

Where:

g

TEA1085; TEA1085A

g

o

6 dB per octave

g

o

f3f2f1

A

pre

-----------=

R33

0

12 dB per octave

18 dB per octave

speech Larsen

Fig.9 Third-order high-pass filter.

i

DCA

-----------=

V

m

20 log f

MGR038

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:

1

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

f1

2πR

eg

f2

------------------------------=

2πR33C24

f3

------------------------------ 1/(2πR25C22)==
2πR26C23

1

1

C24

where R

R30 R31×

-----------------------------==

eq

R30 R31+

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

Larsen limiter capacitor (LLC) pin 12

A 1 µF capacitor (C26) is connected externally between

and LLC to determine the attack and release timing of

V

SS

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 VSS.

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 VSS. 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.

March 1992 11

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

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:

V

DTI1

Where: I




DCA

With the component values given in Fig.16, I
thus V

= 18.8 mV.

DTI1

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

∆V

LLC

---------------- -=

S

1i

∆

τ

With C26 = 1 µF and R36 = 120 kΩ this results in
S

= 10 V/s.

1i

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

the attack delay time t
equation:

ad

C26 R36×

--------------------------------------=

23k1–×()×

t

I

1.25

-----------

R25

DCA

----------- -–

2

2R33×× if f > f3 in Fig.9()=

= the DC current into DCA

during charge is given in the equation:

LLC

1.25

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

C26 R36×

, thus for a continuous signal at DTI

DTI1

ad

Vs⁄()=

(see Fig.10) is determined by the

DCA

= 11 µA

TEA1085; TEA1085A

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

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

(t

LAa

residual Larsen signal is determined by a second
threshold level. This level can be set by resistor R34
connected between THL2 and V
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
The second threshold level at DTI is determined by the
equation:

V

DTI2

Where: I




DCA

I

1.25

-----------

R34

DCA

----------- -–

2 R33 if f > f3 in Fig.9()××=

2

= the DC current into DCA

With the component values given in Fig.16,
V

= 6.9 mV.

DTI2

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

The slope of V

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

LLC

equation:

∆V

LLC

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

S

la

∆

τ

1.25

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

2C26× R34×

Where: C26 = 1 µF and R36 = 100 kΩ, S

. The second threshold

SS

DTI2

Vs⁄()==

= 5 V/s

la

.

Where k = t

1

/ T

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

) is exceeded by the signal level at

DTI1

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 ≤ tad≤ 160 ms, for
V

≥ 100 mV(RMS)

DTI

March 1992 12

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'

). This time period is determined by capacitor C26

(t

LAr

connected to LLC and resistor R36 connected to SIC.
Where: C26 = 1 µF and R36 = 120 kΩ, t

= 250 ms

LAr

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.

Philips Semiconductors Preliminary specification



Listening-in circuit for line-powered
telephone sets

handbook, full pagewidth

V

V

DTI

LLC

0.5 V

0 V

slope S

1

li

listen-in mode listen-in modeLarsen mode

TEA1085; TEA1085A

slope S

la

0.63 V

t

ad

t

LAa

t

LAr

MGR039

Where:

Change of receive gain

handbook, full pagewidth

Where:

t

1

k

--- -=

T

G

v

--------- -=

G

vo

Nominal receive gain = 20 log Gvo= 35 dB

Fig.10 Dynamic behaviour of Larsen limiter (in open-loop condition).

−V

DTI

^

V

DTI

V

DTI1

t

1

T

MGR040

=

k0.5–

V

DTI1

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

sin

arc



ˆ



V

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

DTI

π

Fig.11 Definition of duty cycle k.

March 1992 13

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

TEA1085; TEA1085A

telephone sets

LIMITING VALUES

In accordance with the Absolute Maximum System (IEC 134)

SYMBOL PARAMETER CONDITIONS MIN. MAX. UNIT

V

V
V
I

SUP

P

T
T
T

SUP

SREF
n

tot

amb
stg
j

positive supply voltage

continuous − 12 V
during switch-on or line interruption − 13.2 V
repetitive supply voltage from 1 ms to 5 s with 12 Ω current

− 28 V
limiting resistor in
series with supply

supply reference voltage VSS− 0.5 V

+ 0.5 V

SUP

voltage on all other pins VSS − 0.5 VBB + 0.5 V
supply current

TEA1085/TEA1085A see Fig.12 − 120 mA
TEA1085T/TEA1085AT see Fig.13 − 120 mA

total power dissipation T

= 75 °C;

amb

Tj = 125 °C

TEA1085/TEA1085A − 1W

TEA1085T/TEA1085AT − 666 mW
operating ambient temperature range −25 +75 °C
storage temperature range −40 +125 °C
junction temperature −+125 °C

THERMAL RESISTANCE

SYMBOL PARAMETER CONDITIONS

R

th j-a

from junction to ambient in free air

TEA1085/TEA1085A 50 K/W
TEA1085T/TEA1085AT note 1 75 K/W

Note

1. Device mounted on a glass epoxy board 40.1 × 19.1 × 1.5 mm.

THERMAL

RESISTANCE

March 1992 14

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

(3)

V

MGR041

(2)

SUP

(1)

(V)

130

handbook, halfpage

I

SUP

(mA)

110

90

70

50

30

212

(1) T

amb

(2) T

amb

(3) T

amb

46810

= 55 °C; P
= 65 °C; P
= 75 °C; P

= 1.4 W.

tot

= 1.2 W.

tot

= 1.0 W.

tot

Fig.12 TEA1085/TEA1085A safe operating area.

TEA1085; TEA1085A

130

handbook, halfpage

I

SUP

(mA)

110

90

(5)

70

50

30

212

(1) T

amb

(2) T

amb

(3) T

amb

(4) T

amb

(5) T

amb

46810

=35°C; P
= 45 °C; P
= 55 °C; P
= 65 °C; P
= 75 °C; P

= 1.2 W.

tot

= 1.07 W.

tot

= 0.93 W.

tot

= 0.8 W.

tot

= 0.666 W.

tot

Fig.13 TEA1085T/TEA1085AT safe operating

area.

(4)

(2)

(3)

V

SUP

MGR042

(1)

(V)

March 1992 15

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

TEA1085; TEA1085A

telephone sets

CHARACTERISTICS

= 4.2 V; VSS = 0 V; I

V

SREF

OFF (listening-in mode); MUTE (TEA1085A) = HIGH (listening-in mode); GSC1 = GSC2 = LOW; 50 Ω loudspeaker;
no R38; test circuit Fig.14; unless otherwise specified

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

Supplies

V

SUP

V

SUP-SREF

V

BB

∆V

BB

∆V

BB

I

SUP

minimum DC input voltage − VBB + 0.7 − V
internal reference voltage 275 315 355 mV
stabilized supply voltage no R38; I

variation from
I

= 15 to 120 mA

SUP

/∆T variation with temperature no R38; I

minimum operating current − 4.2 5.5 mA
THD distortion of AC signal on SUP V
V

no(RMS)

noise between SUP and V

current consumption in

power-down condition
I

SUP

I

BB

Loudspeaker amplifier inputs LSI1 and LSI2

|Zi| input impedance

G

∆G

∆G

v

v

v

voltage gain with 50 Ω load I

variation with signal level I

variation with frequency

referred to 1 kHz

∆G

v

variation with temperature

referred to 25 °C

= 15 mA; V

SUP

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

SUP

= 15 mA 3.4 3.6 3.8 V

SUP

= 25 °C; PD = LOW; MUTE (TEA1085) =

amb

− 10 − mV

R38 = 39.2 kΩ between

EE

pins V
V
I

SUP

SS

= 5.2 V;

SREF

= 15 mA

SUP(RMS)

and VA;

SUP

= 1 V − 0.3 − %

= 15 mA tbf −0.2 tbf V

4.2 4.45 4.7 V

−−72 − dBmp

PD = HIGH

V

= 4.5 V − 55 75 µA

SUP

VBB = 3.6 V − 400 550 µA

single ended 7.5 9.5 11.5 kΩ
differential 15 19 23 kΩ

= 15 mA;

SUP

Vi = 1.8 mV(RMS)
single ended 34 35 36 dB
BTL output 39.9 40.9 41.9 dB

= 50 mA;

SUP

Vi = 1.8 mV(RMS) and
14 mV(RMS)

single ended −+0.1 0.4 dB
BTL output −+0.2 0.6 dB
f = 300 Hz and 3400 Hz;

Vi = 1.8 mV(RMS)
single ended −± 0.1 − dB
BTL output −± 0.1 − dB
T

= −25 to +75 °C

amb

single ended −± 0.4 − dB
BTL output −± 0.5 − dB

March 1992 16

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

TEA1085; TEA1085A

telephone sets

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

Loudspeaker outputs QLS1 and QLS2

V

o(p-p)

output voltage (peak-to-peak

value)

single ended I

bridge tied load I

THD total harmonic distortion V

single ended I

bridge tied load I

V

o(p-p)

output voltage (peak-to-peak

value)

single ended I

Dynamic limiter

THD total harmonic distortion Vi = 22 mV(RMS)

single ended I

bridge tied load I

t

att

dynamic behaviour of limiter

attack time; Vi jumps from

10 mV(RMS) to 65 mV(RMS)

voltage limiter I
current limiter I
V

limiter I

BB

t

rel

release time; Vi jumps from

65 mV(RMS) to 10 mV(RMS)
V

BBO

threshold VBB limiter below

which gain reduction starts
V

no(RMS)

noise output voltage 1 kΩ between inputs

single ended − 170 −µV
bridge tied load − 350 −µV

Vi = 22 mV(RMS)

= 9 mA; note 1 1.2 1.45 − V

SUP

I

= 17 mA; note 2 2.5 2.9 − V

SUP

= 23.5 mA; note 2 2.5 2.9 − V

SUP

I

= 32 mA; note 3 3.5 4.0 − V

SUP

= 22 mV(RMS)

i

= 9 mA − 0.4 2 %

SUP

I

= 17 mA − 0.7 2 %

SUP

= 23.5 mA − 0.4 2 %

SUP

Vi = 22 mV(RMS)

= 17 mA;

SUP

V

− VEE = 1 V(RMS)

SUP

1.75 2.15 − V

+10 dB

= 9 mA − 0.5 10 %

SUP

= 17 mA − 1.2 10 %

I

SUP

= 23.5 mA − 0.6 10 %

SUP

single ended load

= 17 mA − 25ms

SUP

= 12 mA − 500 tbf ms

SUP

= 9 mA − 10 − ms

SUP

I

= 17 mA tbf 75 tbf ms

SUP

I

= 9 mA tbf 2.95 tbf V

SUP

LSI1, LSI2;
psophometrically
weighted (P53 curve)

Logic gain control

∆G

v

reduction of voltage gain Vi = 1.8 mV(RMS)

GSC2 = 0, GSC1 = 1 5.8 6.3 6.8 dB
GSC2 = 1, GSC1 = 0 11.7 12.2 12.7 dB
GSC2 = 1, GSC1 = 1 17 18 19 dB

March 1992 17

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

TEA1085; TEA1085A

telephone sets

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

Larsen limiter preamplifier

operational amplifier
G

v0

f

p1

f

p2

G

B

G

v

G

v

Larsen limiter detector

V

DCA-VDTI

G

v

V

THL1

V

THL2

t

LIr

t

ad

t

LAa

t

LAr

V

LLC

−∆V

LLC

∆G

v

open-loop gain − 92 − dB
1st pole − 120 − Hz
2nd pole − 3.3 − MHz
unity gain bandwidth − 4 − MHz

voltage gain f = 3 kHz;

51 52 53 dB
R26 = 10 kΩ;
R29 = 4 MΩ

gain adjustment range 30 − 52 dB

voltage to current convertor
DC offset voltage VBB − V
voltage gain from DTI to DCA V

DTI

= 1 V −25 1 +25 mV

DTI

= 100 mV(RMS);

tbf −0.8 tbf dB
f = 3 kHz

DC voltage at THL1 R35 = 51 kΩ 1.8 1.25 1.33 V
DC voltage at THL2 R34 = 100 kΩ 1.8 1.25 1.33 V
dynamic behaviour with a

f = 3 kHz; see Fig.15

burst at DTI
listen-in release time see Fig.15(a) tbf 40 tbf ms
attack delay time see Fig.15(b)

V

jumps from

DTI

− 160 200 ms

0 to 100 mV (RMS value)
V

jumps from

DTI

100 120 − ms

0 to 1 V (RMS value)

Larsen attack time see Fig.15(b);

V

= 100 mV(RMS)

DTI

− 20 tbf ms

Larsen release time see Fig.15(b)

V

jumps from

DTI

tbf 250 tbf ms

100 mV to 0 mV (RMS

value)
DC voltage at LLC V
reduction of V

to attack

LLC

= 0 V 1.75 1.9 2.0 V

DTI

0.59 0.63 0.68 V

Larsen mode
gain reduction V

= 0.7 V 60 tbf tbf dB

LLC

March 1992 18

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

TEA1085; TEA1085A

telephone sets

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

MUTE input; TEA1085

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

V

IL

V

IH

I

MUTE

t

W

P

R

V

BB(MUTE)

∆G

v

MUTE input; TEA1085A

V

IL

V

IH

I

MUTE

∆G

v

LOW level input voltage 0 − 0.3 V
HIGH level input voltage 1.5 − VBB + 0.4 V
input current MUTE = LOW −−22 −28 µA
minimum input pulse width − 50 −µs
minimum pulse repetition time − 2 − ms
supply voltage below which

tbf 2 tbf V

MUTE toggle is reset
reduction of gain from LSI1,

MUTE = ON 60 100 − dB

LSI2 to QLS1, QLS2

LOW level input voltage 0 − 0.3 V
HIGH level input voltage 1.5 − VBB + 0.4 V
input current MUTE = HIGH − 10 20 µA
reduction of gain from LSI1,

MUTE = HIGH 60 100 − dB

LSI2 to QLS1, QLS2

Power down input

V

IL

V

IH

I

PD

LOW level input voltage 0 − 0.3 V
HIGH level input voltage 1.5 − VBB + 0.4 V
input current PD = HIGH − 2.3 2.8 µA

Logic inputs GSC1 and GSC2

V
V
I

GSC

IL
IH

LOW level input voltage 0 − 0.3 V
HIGH level input voltage 1.5 − VBB + 0.4 V
input current GSC = HIGH − 68µA

Notes

1. Typical output power is 5 mW into 50 Ω

2. Typical output power is 20 mW into 50 Ω

3. Typical output power is 40 mW into 50 Ω

March 1992 19

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March 1992 20

I

R1 R20

CC

I

IN
A

I

LN

I

SUP

agewidth

(1)

C21 R35

R31R30

C24

(1)

V

DTI

V

BB

R34

R32

(1)

C26

(1)

C25

R33

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

telephone sets

15 1

8

2

7

3

I

line

(1) To TEA1060 (SLPE)

The DC current is divided as follows:

V

SUP SREF–

V

-------------------------------=

SUP SREF–

R20

-------------------------------–=

R20

I

SUPIIN

I

LN

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

C1

TEA1060

6

5

10

91618

R5

.

LN

C3

R9

V

LSI

423 14

19

5

6

124 18 8

C20

(1) (1)

V

BB

13

TEA1085

TEA1085A

C31

TEA1085

for

(1)

12

V

BB

for

TEA1085A

10

21

22

R36

R29

9

V

BB

R28

R27

C27

R26

R25

C23

V

m

C22

R

L

50 Ω

MGR043

16

720 1723

C28

1115

(1)

(1)

TEA1085; TEA1085A

Fig.14 Test circuit.

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

Table 2 Component values in test circuit Fig.14

COMPONENT CONDITION VALUE UNIT

Resistor

R1 620 Ω
R5 3.6 kΩ
R9 20 Ω
R20 150 Ω
R25 10 kΩ
R26 10 kΩ
R27 8 MΩ
R28 8 MΩ
R29 4 MΩ
R30 100 kΩ
R31 220 kΩ
R32 100 kΩ
R33 500 Ω
R34 100 kΩ
R35 51 kΩ
R36 120 kΩ

TEA1085; TEA1085A

Capacitor

C1 100 µF
C3 4.7 µF
C20 470 µF
C21 68 pF
C22 2.2 µF
C23 2.2 µF
C24 100 nF
C25 330 nF
C26 1 µF
C27 220 µF
C28 330 nF
C31 TEA1085 only 10 nF

March 1992 21

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

handbook, full pagewidth

V

LLCO

V

DTI

200 ms

0.63 V

V

LLC

t

ad

t

LAa

t

LAr

TEA1085; TEA1085A

V

DTI

100 ms

V

LLC

t

LIr

MGR044

(b) Attack delay (tad), Larsen attack time (t
Larsen release time (t
V

= 100 mV(RMS) and 1 V(RMS); f = 3 kHz.

DTI

LAr

);

Fig.15 Test signals for Larsen level limiter.

LAa

),

(a) Listen-in release time (t
V

= 100 mV(RMS); f = 3 kHz.

DTI

LIr

);

March 1992 22

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March 1992 23

L1

handbook, full pagewidth

(1)

R31R30

V

BB

(1)

R32

(1)

C25

(1)

APPLICATION INFORMATION

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

telephone sets

LINE

TONE

DIALLER

DP DP

DP

interrupt

C1

R1 R20

15 1

13

TEA1060

10 16 18

C3

C21 R35

423 14

12

8

7

C2

5

DP

R24

C29

RV20

C30

C11

19 9

5

6

12418 8

C32 C20 R38R9

(1) (1)

V

BB

(1)

R34

13

TEA1085

TEA1085A

C31

for

TEA1085

12

(1)

C26

16

V

BB

for
TEA1085A

R33

720 1723

C28

C24

10

21

22

R36

V

R29

BB

R28

R27

C27

R26

R25

(1)

C23

to TEA1060
pins 7 and 8

C22

MLA039

TEA1085; TEA1085A

1115

(1)

(1)

(1) To TEA1060 (SLPE).

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

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

TEA1085; TEA1085A

telephone sets

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 (VBB) 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

COMPONENT CONDITION VALUE UNIT

Resistor

R20 150 Ω
R24 note 1 1 kΩ
R25 10 kΩ
R26 10 kΩ
R27 note 1 3.3 MΩ
R28 note 1 3.3 MΩ
R29 note 1 1.65 MΩ
R30 100 kΩ
R31 220 kΩ
R32 100 kΩ
R33 500 Ω
R34 100 kΩ
R35 51 kΩ
R36 120 kΩ
RV20 note 1 1 kΩ

Capacitor

C11 4.7 nF
C20 470 µF
C21 47 pF
C22 4.7 nF
C23 4.7 nF
C24 4.7 nF
C25 330 nF
C26 1 µF
C27 47 µF
C28 330 nF
C29 220 nF
C30 220 nF
C31 TEA1085 only 10 nF

Coil

L1 150 µH

Note

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

March 1992 24

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

PACKAGE OUTLINES

DIP24: plastic dual in-line package; 24 leads (600 mil)

D

seating plane

L

Z

24

e

b

TEA1085; TEA1085A

SOT101-1

M

E

A

2

A

A

1

w M

b

1

13

c

(e )

1

M

H

pin 1 index

1

0 5 10 mm

DIMENSIONS (inch dimensions are derived from the original mm dimensions)

A

A

A

UNIT

inches

Note

1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.

max.

mm

OUTLINE
VERSION

SOT101-1

1 2

min.

max.

0.066

0.051

IEC JEDEC EIAJ

051G02 MO-015AD

1.7

1.3

b

b

1

0.53

0.38

0.021

0.015

0.32

0.23

0.013

0.009

REFERENCES

cD E e M

32.0

31.4

1.26

1.24

12

scale

14.1

13.7

0.56

0.54

E

(1)(1)

e

L

3.9

3.4

EUROPEAN

PROJECTION

M

15.80

15.24

0.62

0.60

E

17.15

15.90

0.68

0.63

1

0.15

0.13

H

w

0.252.54 15.24

0.010.10 0.60

ISSUE DATE

92-11-17
95-01-23

Z

max.

2.25.1 0.51 4.0

0.0870.20 0.020 0.16

(1)

March 1992 25

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

SO24: plastic small outline package; 24 leads; body width 7.5 mm

D

c

y

Z

24

13

TEA1085; TEA1085A

SOT137-1

E

H

E

A

X

v M

A

pin 1 index

1

e

0 5 10 mm

DIMENSIONS (inch dimensions are derived from the original mm dimensions)

mm

A

max.

2.65

0.10

A1A

0.30

0.10

0.012

0.004

2.45

2.25

0.096

0.089

A

0.25

0.01

b

3

p

0.49

0.32

0.36

0.23

0.019

0.013

0.014

0.009

2

UNIT

inches

Note

1. Plastic or metal protrusions of 0.15 mm maximum per side are not included.

(1)E(1) (1)

cD

15.6

15.2

0.61

0.60

12

w M

b

p

scale

eHELLpQ

7.6

1.27

7.4

0.30

0.050

0.29

10.65

10.00

0.419

0.394

A

1.4

0.055

Q

2

A

1

detail X

1.1

1.1

0.4

0.043

0.016

1.0

0.043

0.039

0.25

0.01

L

p

L

(A )

0.25 0.1

0.01

A

3

θ

ywv θ

Z

0.9

0.4

0.035

0.004

0.016

o

8

o

0

OUTLINE

VERSION

SOT137-1

IEC JEDEC EIAJ

075E05 MS-013AD

REFERENCES

March 1992 26

EUROPEAN

PROJECTION

ISSUE DATE

95-01-24
97-05-22

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

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

“Data Handbook IC26; Integrated Circuit Packages”

our
(order code 9398 652 90011).

DIP

S

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

R

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.

SO

REFLOW SOLDERING
Reflow soldering techniques are suitable for all SO

packages.

stg max

). If the

TEA1085; TEA1085A

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 °C.

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

AVE SOLDERING

W
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 °C.

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

EPAIRING SOLDERED JOINTS

R
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 °C.

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.

March 1992 27

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

TEA1085; TEA1085A

telephone sets

DEFINITIONS

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.

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.

March 1992 28

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

NOTES

March 1992 29

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

NOTES

March 1992 30

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

NOTES

March 1992 31

Philips Semiconductors – a worldwide company

Argentina: see South America
Australia: 34 Waterloo Road, NORTH RYDE, NSW 2113,

Tel. [phone], Fax. [phone]
Austria: Computerstr. 6, A-1101 WIEN, P.O. Box 213, Tel. [phone],

Fax. [phone]
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220050 MINSK, Tel. [phone], Fax. [phone]

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Brazil: see South America
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51 James Bourchier Blvd., 1407 SOFIA,
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20124 MILANO, Tel. [phone], Fax. [phone]

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TOKYO 108-8507, Tel. [phone], Fax. [phone]

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Malaysia: No. 76 Jalan Universiti, 46200 PETALING JAYA, SELANGOR,
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Mexico: 5900 Gateway East, Suite 200, EL PASO, TEXAS 79905,
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Middle East: see Italy
Netherlands: Postbus 90050, 5600 PB EINDHOVEN, Bldg. VB,

Tel. [phone], Fax. [phone]
New Zealand: 2 Wagener Place, C.P.O. Box 1041, AUCKLAND,

Tel. [phone], Fax. [phone]
Norway: Box 1, Manglerud 0612, OSLO,

Tel. [phone], Fax. [phone]

Pakistan: see Singapore
Philippines: Philips Semiconductors Philippines Inc.,

106 Valero St. Salcedo Village, P.O. Box 2108 MCC, MAKATI,
Metro MANILA, Tel. [phone], Fax. [phone]

Poland: Ul. Lukiska 10, PL 04-123 WARSZAWA,
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Romania: see Italy
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Slovakia: see Austria
Slovenia: see Italy
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2092 JOHANNESBURG, P.O. Box 7430 Johannesburg 2000,
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Tel. [phone], Fax. [phone]

Switzerland: Allmendstrasse 140, CH-8027 ZÜRICH,
Tel. [phone] Fax. [phone]

Taiwan: Philips Semiconductors, 6F, No. 96, Chien Kuo N. Rd., Sec. 1,
TAIPEI, Taiwan Tel. [phone], Fax. [phone]

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209/2 Sanpavuth-Bangna Road Prakanong, BANGKOK 10260,
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Tel. [phone], Fax. [phone]

Ukraine: PHILIPS UKRAINE, 4 Patrice Lumumba str., Building B, Floor 7,
252042 KIEV, Tel. [phone], Fax. [phone]

United Kingdom: Philips Semiconductors Ltd., 276 Bath Road, Hayes,
MIDDLESEX UB3 5BX, Tel. [phone], Fax. [phone]

United States: 811 East Arques Avenue, SUNNYVALE, CA 94088-3409,
Tel. [phone]

Uruguay: see South America
Vietnam: see Singapore
Yugoslavia: PHILIPS, Trg N. Pasica 5/v, 11000 BEOGRAD,

Tel. [phone], Fax.[phone]

For all other countries apply to: Philips Semiconductors,
International Marketing & Sales Communications, Building BE-p, P.O. Box 218,
5600 MD EINDHOVEN, The Netherlands, Fax. [phone]

© Philips Electronics N.V. 1998 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.

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

Printed in The Netherlands 415102/00/02/pp32 Date of release: March 1992 Document order number: 9397 750 nnnnn