Datasheet TEA1085T-C1, TEA1085AT-C1, TEA1085A-C1, TEA1085-C1 Datasheet (Philips)

DATA SH EET

Preliminary specification
File under Integrated Circuits, IC03A

March 1992

INTEGRATED CIRCUITS

TEA1085; TEA1085A

Listening-in circuit for line-powered
telephone sets

March 1992 2

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 24 DIL plastic SOT101B

(1)

TEA1085T/TEA1085AT 24 SO24 plastic SOT137A

(2)

March 1992 3

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

QUICK REFERENCE DATA

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

I

SUP

input current range 4 − 120 mA

V

BB

stabilized supply voltage − 3.6 − V

I

SUP

current consumption PD = HIGH − 55 −µA

G

v

voltage gain loudspeaker amplifier

SE − 35 − dB
BTL − 41 − dB

∆G

v

maximum gain reduction with logic
inputs (3 steps)

− 18 − dB

I

SUP

minimum input current

P

OUT

= 20 mW typ.

into 50 Ω SE

− 15 17 mA

P

OUT

= 40 mW typ.

into 50 Ω BTL

−−32 mA

t

ad(RMS)

Larsen limiter attack delay time V

DTI

jumps from 0 to ≥ 100 mV (RMS value)

100 − 200 ms

V

DTI(RMS)

Larsen limiter threshold level Larsen mode − 7 − mV

G

v

Larsen limiter preamplifier gain setting
range

30 − 52 dB

T

amb

operating ambient temperature range −25 −+75 °C

March 1992 4

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

PD

PREAMPLIFIER

LARSEN

LEVEL LIMITER

MUTE LSI1 LSI2

20 5

DLC

23

2

SUP3SDC

4

SREF

6

QLA
11

DTI
15

TEA1060 (VEE)
TEA1060 (QR)

TEA1060

(MIC)

TEA1060

(MIC)

(2)

(1)

(1)

(1)

2

2

2

2221QLS2

QLS1

109LAI+

GSC1 8
GSC2 7

SIC 17

(1)

V

BB

24

PD

19

V

SS

1

VA

18

LAI−

V

BB

V

BB

4

line

TEA1060

(LN)

13

THL212LLC

14

THL1

16

DCA

(1)

V

BB

(1)

TEA1085

TEA1085A

Fig.1 Block diagram.

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

March 1992 5

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

PIN CONFIGURATION

SYMBOL PIN DESCRIPTION

V

SS

1 negative supply
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

input

LAI+ 10 Larsen limiter preamplifier

non-inverting input
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

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

adjustment
SIC 17 Larsen limiter current stabilizer
VA 18 V

BB

voltage adjustment
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

24 stabilized supply decoupling

Fig.2 Pin configuration.

handbook, halfpage

V

SS

SUP

SDC

SREF

LSI1

LSI2
GSC2
GSC1

LAI−

LAI+

QLA

LLC

V

BB

DLC
QLS2
QLS1

PD
VA

MUTE

SIC
DCA
DTI
THL1
THL2

1
2
3
4
5
6
7
8

9
10
11
12

24
23
22
21

20
19
18
17
16
15
14
13

TEA1085

TEA1085A

MLA415

March 1992 6

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

V

CC

LN

V

EE SLPE

QR

MIC+

MIC−

LAI+

LAI−

TEA1085

TEA1085A

SREF SUP

V

SS

LSI1 LSI2

QLS

LINE

to TEA1060

(SLPE)

March 1992 7

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Supply; SUP, SREF, VBB, VSSand VA

The line current is divided into I

TR

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

V

CC

LN

V

EE SLPE

TEA1085

TEA1085A

V

SS

V

BB

I

line

I

TR

SUP

C20

I

SUP

I

BBO

I

BIAS

I

CC

R1

R9

R38

VA

R20

VOLTAGE

STABILIZER

TR1

TR2

SREF

V

int

LINE

ITR is constant: ITR=V

int

/ R20; I

SUP=Iline

− ICC− I

TR

Where:

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

TR

= 2 mA and I

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

SUP

drops below the supply voltage VBB. VBB is
fixed to a typical value of 3.6 V but can be increased by
means of an external resistor (R38) connected between

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)

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

SUP

− VSS) is determined by the

transmission IC (V

LN−SLPE

); thus:

V

SUP

− VSS = V

LN−SLPE

+ V

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 VSS).

The internal current consumption of the
TEA1085/TEA1085A (I

SUP0

) is typically 4.2 mA (where

V

SUP

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

for powering the loudspeaker is I

SUP

− I

SUP0

.

The current I

SUP0

consists of a bias current of ≈ 0.4 mA for

the circuitry connected to SUP and current I

BB0

of≈ 3.8 mA

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

March 1992 8

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 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

amb

= +25 °C.
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.

Fig.5 Stabilized supply voltage as a function of

R38.

dbook, halfpage

5.5

3.5

MGR035

10 10

2

10

3

3.9

4.3

4.7

5.1

R38 (kΩ)

V

BB

(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 VSS or left open-circuit
1 = applying a voltage ≥ VSS+ 1.5 V

GSC2 GSC1

gain

(dB)

gain reduction

(dB)

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

March 1992 9

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 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).

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

SS

). 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 VSS.
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 standbylistening-in

Fig.7 Mute switch alternatives with the TEA1085.

handbook, full pagewidth

MLA055

MUTE MUTE

V

BB

10 kΩ

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

March 1992 10

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 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

BBO

(Fig.4) at
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

SUP

= 4.5 V in the following

equation:
I

SUP(PD)

= I

BIAS(PD)

= (V

SUP

− 2Vd) / Ra

(where 4.2 V < V

SUP

< VBB+ 3 V)

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

Larsen limiter current stabilizer (SIC) pin 17

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

SS

. The preferred value is 120 kΩ. The internal reference

current is given by the following equation:

I

SIC

= 1.25 / R36; when R36 = 120 kΩ, I

SIC

= 10.5 µA

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

QLA

/ VM = R29 / R26; in the basic application

R25 = R26 = 10 kΩ
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).

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

handbook, full pagewidth

MGR037

LAI+

LAI−

+

−

+

−

R25

R26

R29

C22

C23

V

M

DTI

DCA

I

DCA

THL1 THL2

R27

QLA

C24

R30

R33

R32C25

R31

R35 R34

V

QLA

V

BB

V

SS

V

BB

R28

LARSEN

DETECTOR

LLC

March 1992 11

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 VBB(see Fig.8).

The equation for DC current is:

The equation for AC current is:

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

and C25 = 330 nF
This results in I

DCA

= 11 µA 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

I

DCA

R30

R30 R31+

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

V

BB

1

R32 R33+

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

××=

i

DCA

V

DTI

R33

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

forf>

1
2

-- -

π R33 C25=

i

DCA

V

DTI

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

f1

1

2πR

eg

C24

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

where R

eq

R30 R31×
R30 R31+

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

f2

1

2πR33C24

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

f3

1

2πR26C23

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

Where:

Larsen limiter capacitor (LLC) pin 12

A 1 µF capacitor (C26) is connected externally between
V

SS

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 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.

Fig.9 Third-order high-pass filter.

handbook, halfpage

MGR038

20 log

(dB)

g

g

o

20 log f

f3f2f1

0

12 dB per octave

6 dB per octave

18 dB per octave

speech Larsen

g

i

DCA

V

m

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

g

o

A

pre

R33

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

March 1992 12

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 µA

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 µF and R36 = 120 kΩ this results in
S

1i

= 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

ad

(see Fig.10) is determined by the

equation:

Where k = t

1

/ 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 ≤ tad≤ 160 ms, for
V

DTI

≥ 100 mV(RMS)

V

DTI1

1.25
R25

-----------

I

DCA

2

----------- -–





2R33×× if f > f3 in Fig.9()=

S

1i

∆V

LLC

∆

τ

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

1.25

C26 R36×

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

Vs⁄()=

t

ad

C26 R36×

23k1–×()×

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

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

SS

. 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 µF and R36 = 100 kΩ, S

la

= 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 µF and R36 = 120 kΩ, 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.

V

DTI2

1.25
R34

-----------

I

DCA

2

----------- -–





2 R33 if f > f3 in Fig.9()××=

S

la

∆V

LLC

∆

τ

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

1.25

2C26× R34×

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

Vs⁄()==

March 1992 13

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

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

Where:

Change of receive gain

G

v

G

vo

--------- -=

Nominal receive gain = 20 log Gvo= 35 dB

handbook, full pagewidth

MGR039

V

DTI

V

LLC

slope S

li

slope S

la

t

ad

t

LAr

0.5 V

1

0 V

listen-in mode listen-in modeLarsen mode

t

LAa

0.63 V

handbook, full pagewidth

MGR040

−V

DTI

V

DTI1

t

1

T

V

DTI

^

Fig.11 Definition of duty cycle k.

Where:

k

t

1

T

--- -=

k0.5–

arc

V

DTI1

V

ˆ

DTI

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







sin

π

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

=

March 1992 14

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

V

SUP

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

limiting resistor in
series with supply

− 28 V

V

SREF

supply reference voltage VSS− 0.5 V

SUP

+ 0.5 V

V

n

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

I

SUP

supply current

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

P

tot

total power dissipation T

amb

= 75 °C;

Tj = 125 °C
TEA1085/TEA1085A − 1W
TEA1085T/TEA1085AT − 666 mW

T

amb

operating ambient temperature range −25 +75 °C

T

stg

storage temperature range −40 +125 °C

T

j

junction temperature −+125 °C

SYMBOL PARAMETER CONDITIONS

THERMAL

RESISTANCE

R

th j-a

from junction to ambient in free air

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

March 1992 15

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Fig.12 TEA1085/TEA1085A safe operating area.

(1) T

amb

= 55 °C; P

tot

= 1.4 W.

(2) T

amb

= 65 °C; P

tot

= 1.2 W.

(3) T

amb

= 75 °C; P

tot

= 1.0 W.

handbook, halfpage

212

130

30

50

MGR041

70

90

110

46810

V

SUP

(V)

(2)

(3)

(1)

I

SUP

(mA)

Fig.13 TEA1085T/TEA1085AT safe operating

area.

(1) T

amb

=35°C; P

tot

= 1.2 W.

(2) T

amb

= 45 °C; P

tot

= 1.07 W.

(3) T

amb

= 55 °C; P

tot

= 0.93 W.

(4) T

amb

= 65 °C; P

tot

= 0.8 W.

(5) T

amb

= 75 °C; P

tot

= 0.666 W.

handbook, halfpage

212

130

30

50

MGR042

70

90

110

46810

V

SUP

(V)

(2)

(3)

(4)

(5)

(1)

I

SUP

(mA)

March 1992 16

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

CHARACTERISTICS

V

SREF

= 4.2 V; VSS = 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 Ω loudspeaker;
no R38; test circuit Fig.14; unless otherwise specified

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

Supplies

V

SUP

minimum DC input voltage − VBB + 0.7 − V

V

SUP-SREF

internal reference voltage 275 315 355 mV

V

BB

stabilized supply voltage no R38; I

SUP

= 15 mA 3.4 3.6 3.8 V

∆V

BB

variation from
I

SUP

= 15 to 120 mA

− 10 − mV

R38 = 39.2 kΩ between
pins V

SS

and VA;

V

SREF

= 5.2 V;

I

SUP

= 15 mA

4.2 4.45 4.7 V

∆V

BB

/∆T variation with temperature no R38; I

SUP

= 15 mA tbf −0.2 tbf V

I

SUP

minimum operating current − 4.2 5.5 mA

THD distortion of AC signal on SUP V

SUP(RMS)

= 1 V − 0.3 − %

V

no(RMS)

noise between SUP and V

EE

−−72 − dBmp

current consumption in
power-down condition

PD = HIGH

I

SUP

V

SUP

= 4.5 V − 55 75 µA

I

BB

VBB = 3.6 V − 400 550 µA

Loudspeaker amplifier inputs LSI1 and LSI2

|Zi| input impedance

single ended 7.5 9.5 11.5 kΩ
differential 15 19 23 kΩ

G

v

voltage gain with 50 Ω load I

SUP

= 15 mA;

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

∆G

v

variation with signal level I

SUP

= 50 mA;
Vi = 1.8 mV(RMS) and
14 mV(RMS)

single ended −+0.1 0.4 dB
BTL output −+0.2 0.6 dB

∆G

v

variation with frequency
referred to 1 kHz

f = 300 Hz and 3400 Hz;
Vi = 1.8 mV(RMS)

single ended −± 0.1 − dB
BTL output −± 0.1 − dB

∆G

v

variation with temperature
referred to 25 °C

T

amb

= −25 to +75 °C

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

March 1992 17

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Loudspeaker outputs QLS1 and QLS2

V

o(p-p)

output voltage (peak-to-peak
value)

Vi = 22 mV(RMS)

single ended I

SUP

= 9 mA; note 1 1.2 1.45 − V
I

SUP

= 17 mA; note 2 2.5 2.9 − V

bridge tied load I

SUP

= 23.5 mA; note 2 2.5 2.9 − V
I

SUP

= 32 mA; note 3 3.5 4.0 − V

THD total harmonic distortion V

i

= 22 mV(RMS)

single ended I

SUP

= 9 mA − 0.4 2 %
I

SUP

= 17 mA − 0.7 2 %

bridge tied load I

SUP

= 23.5 mA − 0.4 2 %

V

o(p-p)

output voltage (peak-to-peak
value)

Vi = 22 mV(RMS)

single ended I

SUP

= 17 mA;
V

SUP

− VEE = 1 V(RMS)

1.75 2.15 − V

Dynamic limiter

THD total harmonic distortion Vi = 22 mV(RMS)

+10 dB

single ended I

SUP

= 9 mA − 0.5 10 %
I

SUP

= 17 mA − 1.2 10 %

bridge tied load I

SUP

= 23.5 mA − 0.6 10 %

t

att

dynamic behaviour of limiter
attack time; Vi jumps from
10 mV(RMS) to 65 mV(RMS)

single ended load

voltage limiter I

SUP

= 17 mA − 25ms

current limiter I

SUP

= 12 mA − 500 tbf ms

V

BB

limiter I

SUP

= 9 mA − 10 − ms

t

rel

release time; Vi jumps from
65 mV(RMS) to 10 mV(RMS)

I

SUP

= 17 mA tbf 75 tbf ms

V

BBO

threshold VBB limiter below
which gain reduction starts

I

SUP

= 9 mA tbf 2.95 tbf V

V

no(RMS)

noise output voltage 1 kΩ between inputs

LSI1, LSI2;
psophometrically
weighted (P53 curve)

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

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

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

March 1992 18

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Larsen limiter preamplifier

operational amplifier

G

v0

open-loop gain − 92 − dB

f

p1

1st pole − 120 − Hz

f

p2

2nd pole − 3.3 − MHz

G

B

unity gain bandwidth − 4 − MHz

G

v

voltage gain f = 3 kHz;

R26 = 10 kΩ;
R29 = 4 MΩ

51 52 53 dB

G

v

gain adjustment range 30 − 52 dB

Larsen limiter detector

voltage to current convertor

V

DCA-VDTI

DC offset voltage VBB − V

DTI

= 1 V −25 1 +25 mV

G

v

voltage gain from DTI to DCA V

DTI

= 100 mV(RMS);

f = 3 kHz

tbf −0.8 tbf dB

V

THL1

DC voltage at THL1 R35 = 51 kΩ 1.8 1.25 1.33 V

V

THL2

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

burst at DTI

f = 3 kHz; see Fig.15

t

LIr

listen-in release time see Fig.15(a) tbf 40 tbf ms

t

ad

attack delay time see Fig.15(b)

V

DTI

jumps from

0 to 100 mV (RMS value)

− 160 200 ms

V

DTI

jumps from

0 to 1 V (RMS value)

100 120 − ms

t

LAa

Larsen attack time see Fig.15(b);

V

DTI

= 100 mV(RMS)

− 20 tbf ms

t

LAr

Larsen release time see Fig.15(b)

V

DTI

jumps from
100 mV to 0 mV (RMS
value)

tbf 250 tbf ms

V

LLC

DC voltage at LLC V

DTI

= 0 V 1.75 1.9 2.0 V

−∆V

LLC

reduction of V

LLC

to attack

Larsen mode

0.59 0.63 0.68 V

∆G

v

gain reduction V

LLC

= 0.7 V 60 tbf tbf dB

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

March 1992 19

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

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

MUTE input; TEA1085

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

V

IL

LOW level input voltage 0 − 0.3 V

V

IH

HIGH level input voltage 1.5 − VBB + 0.4 V

I

MUTE

input current MUTE = LOW −−22 −28 µA

t

W

minimum input pulse width − 50 −µs

P

R

minimum pulse repetition time − 2 − ms

V

BB(MUTE)

supply voltage below which
MUTE toggle is reset

tbf 2 tbf V

∆G

v

reduction of gain from LSI1,
LSI2 to QLS1, QLS2

MUTE = ON 60 100 − dB

MUTE input; TEA1085A

V

IL

LOW level input voltage 0 − 0.3 V

V

IH

HIGH level input voltage 1.5 − VBB + 0.4 V

I

MUTE

input current MUTE = HIGH − 10 20 µA

∆G

v

reduction of gain from LSI1,
LSI2 to QLS1, QLS2

MUTE = HIGH 60 100 − dB

Power down input

V

IL

LOW level input voltage 0 − 0.3 V

V

IH

HIGH level input voltage 1.5 − VBB + 0.4 V

I

PD

input current PD = HIGH − 2.3 2.8 µA

Logic inputs GSC1 and GSC2

V

IL

LOW level input voltage 0 − 0.3 V

V

IH

HIGH level input voltage 1.5 − VBB + 0.4 V

I

GSC

input current GSC = HIGH − 68µA

SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT

March 1992 20

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

telephone sets

TEA1085; TEA1085A

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agewidth

MGR043

3

2

5

6

6

5

19

9

7

8

10

91618

15 1

423 14

C3

C1

C20

R9

R5

R1 R20

C21 R35

R28

(1)

(1) (1)

C28

(1)

R36

(1)

13

R34

16

R33

R29

R26

R31R30

R32

(1)

(1)

12

C26

1115

124 18 8

720 1723

C23

C24

C27

C25

(1)

V

BB

10

21

22

R27

R25

C22

V

BB

V

BB

V

BB

C31

(1)

for

TEA1085

for

TEA1085A

TEA1060

TEA1085

TEA1085A

R

L

50 Ω

A

I

IN

I

SUP

I

line

V

LSI

V

DTI

I

LN

I

CC

V

m

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

LN

.

I

SUPIIN

V

SUP SREF–

R20

-------------------------------–=

I

LN

V

SUP SREF–

R20

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

(1) To TEA1060 (SLPE)

March 1992 21

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

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

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 22

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

Fig.15 Test signals for Larsen level limiter.

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

LAa

),

Larsen release time (t

LAr

);

V

DTI

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

handbook, full pagewidth

MGR044

0.63 V

V

LLCO

V

LLC

V

DTI

t

ad

200 ms

t

LAr

t

LAa

V

LLC

100 ms

t

LIr

V

DTI

(a) Listen-in release time (t

LIr

);

V

DTI

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

March 1992 23

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered

telephone sets

TEA1085; TEA1085A

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APPLICATION INFORMATION

handbook, full pagewidth

MLA039

DIALLER

TONE

DP DP

DP

LINE

DP

interrupt

13

6

5

19 9

7

5

8

12

10 16 18

15 1

423 14

C3

C2

C1

C11

C29

C30

C32 C20 R38R9

R24

RV20

R1 R20

L1

C21 R35

R28

(1)

(1) (1)

C28

(1)

(1)

(1)

R36

(1)

13

R34

16

R33

R29

R26

R31R30

R32

(1)

(1)

12

C26

1115

12418 8

720 1723

C24

C23

C27

C25

(1)

V

BB

10

21

22

R27

R25

C22

V

BB

V

BB

V

BB

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 24

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 (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

Note

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

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

March 1992 25

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

PACKAGE OUTLINES

UNIT

A

max.

1 2

b

1

cD E e M

H

L

REFERENCES

OUTLINE
VERSION

EUROPEAN

PROJECTION

ISSUE DATE

IEC JEDEC EIAJ

mm

inches

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

SOT101-1

92-11-17
95-01-23

A

min.

A

max.

b

w

M

E

e

1

1.7

1.3

0.53

0.38

0.32

0.23

32.0

31.4

14.1

13.7

3.9

3.4

0.252.54 15.24

15.80

15.24

17.15

15.90

2.25.1 0.51 4.0

0.066

0.051

0.021

0.015

0.013

0.009

1.26

1.24

0.56

0.54

0.15

0.13

0.010.10 0.60

0.62

0.60

0.68

0.63

0.0870.20 0.020 0.16

051G02 MO-015AD

M

H

c

(e )

1

M

E

A

L

seating plane

A

1

w M

b

1

e

D

A

2

Z

24

1

13

12

b

E

pin 1 index

0 5 10 mm

scale

Note

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

Z

max.

(1)

(1)(1)

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

SOT101-1

March 1992 26

Philips Semiconductors Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

UNIT

A

max.

A1A2A

3

b

p

cD

(1)E(1) (1)

eHELLpQ

Z

ywv θ

REFERENCES

OUTLINE

VERSION

EUROPEAN

PROJECTION

ISSUE DATE

IEC JEDEC EIAJ

mm

inches

2.65

0.30

0.10

2.45

2.25

0.49

0.36

0.32

0.23

15.6

15.2

7.6

7.4

1.27

10.65

10.00

1.1

1.0

0.9

0.4

8
0

o
o

0.25 0.1

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

Note

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

1.1

0.4

SOT137-1

X

12

24

w M

θ

A

A

1

A

2

b

p

D

H

E

L

p

Q

detail X

E

Z

c

L

v M

A

13

(A )

3

A

y

0.25

075E05 MS-013AD

pin 1 index

0.10

0.012

0.004

0.096

0.089

0.019

0.014

0.013

0.009

0.61

0.60

0.30

0.29

0.050

1.4

0.055

0.419

0.394

0.043

0.039

0.035

0.016

0.01

0.25

0.01

0.004

0.043

0.016

0.01

e

1

0 5 10 mm

scale

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

SOT137-1

95-01-24
97-05-22

March 1992 27

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

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

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.

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.
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 °C.

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

W

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 °C.

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

R

EPAIRING SOLDERED JOINTS

Fix the component by first soldering two diagonally­opposite 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.

March 1992 28

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.

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 Preliminary specification

Listening-in circuit for line-powered
telephone sets

TEA1085; TEA1085A

NOTES

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

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© Philips Electronics N.V. 1998 SCA60
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Printed in The Netherlands 415102/00/02/pp32 Date of release: March 1992 Document order number: 9397 750 nnnnn