PHILIPS TEA1085AT

INTEGRATED CIRCUITS
DATA SHEET
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
TEA1085; TEA1085A
FEATURES
GENERAL DESCRIPTION
• Internal supply
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.
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
ORDERING INFORMATION
EXTENDED TYPE
NUMBER
PACKAGE
PINS
PIN POSITION
MATERIAL
CODE
TEA1085/TEA1085A
24
DIL
plastic
SOT101B(1)
TEA1085T/TEA1085AT
24
SO24
plastic
SOT137A(2)
Notes
1. SOT101-1; 1998 Jun 18.
2. SOT137-1; 1998 Jun 18.
March 1992
2
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
QUICK REFERENCE DATA
SYMBOL
PARAMETER
CONDITIONS
MIN.
TYP.
MAX.
UNIT
ISUP
input current range
4
−
120
mA
VBB
stabilized supply voltage
−
3.6
−
V
ISUP
current consumption
PD = HIGH
−
55
−
µA
Gv
voltage gain loudspeaker amplifier
SE
−
35
−
dB
BTL
−
41
−
dB
−
18
−
dB
POUT = 20 mW typ.
into 50 Ω SE
−
15
17
mA
POUT = 40 mW typ.
into 50 Ω BTL
−
−
32
mA
100
−
200
ms
−
7
−
mV
∆Gv
maximum gain reduction with logic
inputs (3 steps)
ISUP
minimum input current
tad(RMS)
Larsen limiter attack delay time VDTI
jumps from 0 to ≥ 100 mV (RMS value)
VDTI(RMS)
Larsen limiter threshold level
Gv
Larsen limiter preamplifier gain setting
range
30
−
52
dB
Tamb
operating ambient temperature range
−25
−
+75
°C
March 1992
Larsen mode
3
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line
(1)
TEA1060
(LN)
SREF SUP
4
2
SDC
3
THL1 THL2 LLC
14
13
12
DCA
DTI
QLA
16
15
11
TEA1060
(MIC)
9 LAI−
VSS 1
VBB 24
LARSEN
LEVEL
LIMITER
SUPPLY
PD
PD 19
VA 18
PREAMPLIFIER
LARSEN
LEVEL LIMITER
10 LAI+
4
(1)
TEA1060
(MIC)
VBB
VBB
4
GSC1 8
GSC2 7
(1)
SIC 17
I-STABILIZATION
LOGIC GAIN
CONTROL
Philips Semiconductors
(1)
Listening-in circuit for line-powered
telephone sets
ndbook, full pagewidth
March 1992
VBB
TEA1085
TEA1085A
2
2
2
START
CIRCUIT
21 QLS1
POWER
AMPLIFIER
23
20
5
6
DLC
MUTE
LSI1
LSI2
(2)
(1)
MGR032
TEA1060 (VEE)
TEA1060 (QR)
(1) To TEA1060 (SLPE).
(2) See Fig.16.
Fig.1 Block diagram.
Preliminary specification
(1)
22 QLS2
TEA1085; TEA1085A
RECEIVING
AMPLIFIER
MUTE
PEAK AND
CURRENT
LIMITER
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
PIN CONFIGURATION
SYMBOL PIN
DESCRIPTION
VSS
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
VBB 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
VBB
24
stabilized supply decoupling
March 1992
handbook, halfpage
VSS 1
24 VBB
SUP 2
23 DLC
SDC 3
22 QLS2
SREF 4
21 QLS1
LSI1 5
20 MUTE
GSC2 7
TEA1085 19 PD
TEA1085A 18 VA
GSC1 8
17 SIC
LSI2 6
LAI− 9
16 DCA
LAI+ 10
15 DTI
QLA 11
14 THL1
LLC 12
13 THL2
MLA415
Fig.2 Pin configuration.
5
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
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.
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
handbook, full pagewidth
VCC
TEA1060
LINE
LN
SREF
SUP
MIC+
LAI+
MIC−
LAI− TEA1085A
TEA1085
QLS
QR
VEE
SLPE
LSI1
LSI2
MGR033
VSS
to TEA1060
(SLPE)
Fig.3 Interconnection of the TEA1085/TEA1085A with the TEA1060.
March 1992
6
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
Supply; SUP, SREF, VBB, VSS and VA
The line current is divided into ITR for the TEA1060 and ISUP for the TEA1085/TEA1085A.
The supply arrangement is illustrated in Fig.4.
handbook, full pagewidth
Iline
ICC
ISUP
R1
ITR
SUP
R20
TR2
Vint
VCC
VBB
TR1
IBBO
LN
VOLTAGE
STABILIZER
SREF
TEA1060
LINE
VEE
TEA1085
TEA1085A
SLPE
C20
IBIAS
VSS
VA
R38
MGR034
R9
ITR is constant: ITR = Vint / R20; ISUP = Iline − ICC − ITR
Fig.4 Supply arrangement.
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.
Where:
Vint
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
ICC
is the internal current consumption of the
TEA106X (≈ 1 mA)
The DC voltage (VSUP − VSS) is determined by the
transmission IC (VLN−SLPE); thus:
VSUP − VSS = VLN−SLPE + Vint.
The minimum DC voltage that can be applied to this input
is VBB(max) + 0.4 V.
A practical value for R20 is 150 Ω. This value of resistance
produces a value for ITR = 2 mA and ISUP = Iline − 3 mA.
Where: VBB(max) is the worst case supply voltage (this
depends on the setting of R38, which is connected
between VA and VSS).
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 VSUP 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
March 1992
The internal current consumption of the
TEA1085/TEA1085A (ISUP0) is typically 4.2 mA (where
VSUP − VSS = 4.5 V, MUTE off). Thus the current available
for powering the loudspeaker is ISUP − ISUP0.
The current ISUP0 consists of a bias current of ≈ 0.4 mA for
the circuitry connected to SUP and current IBB0 of ≈ 3.8 mA
which is used for the circuitry connected to VBB (see Fig.4).
7
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
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.
MGR035
5.5
ndbook, halfpage
VBB
(V)
5.1
Table 1
4.7
GSC2
GSC1
0
0
35
0
0
1
28.7
6.3
1
0
22.2
12.2
1
1
17
18
4.3
3.9
Fig.5
102
R38 (kΩ)
103
gain reduction
(dB)
0 = connection to VSS or left open-circuit
1 = applying a voltage ≥ VSS + 1.5 V
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 Tamb = +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.
March 1992
gain
(dB)
Where:
VBB = 3.60 V
3.5
10
Data for microcontroller drive of logic inputs
8
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
Dynamic limiter (DLC) pin 23
MUTE input (MUTE) pin 20; TEA1085A
To prevent distortion of the signal at the loudspeaker
outputs the gain of the amplifier is reduced rapidly when:
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.
• 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)
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 VSS). 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.
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).
handbook, full pagewidth LSI1
MUTE
QLS1
standby
listening-in
standby
MGR036
Fig.6 Mute toggle function of the TEA1085.
handbook, full pagewidth
VBB
MUTE
MUTE
10 kΩ
MLA055
(a) Break contact.
(b) Make contact.
Fig.7 Mute switch alternatives with the TEA1085.
March 1992
9
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
Power down input (PD) pin 19
ISIC = 1.25 / R36; when R36 = 120 kΩ, ISIC = 10.5 µA
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 IBBO (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 VSUP = 4.5 V in the following
equation:
Changing the value of R36 will affect the timing of the
Larsen level limiter system.
ISUP(PD) = IBIAS(PD) = (VSUP − 2Vd) / Ra
(where 4.2 V < VSUP < VBB + 3 V)
The gain between QLA and the microphone input is given
by the following equation (the high-pass filter is not taken
into account):
2Vd = the voltage drop across 2 internal diodes (≈ 1.3 V)
Ra = an internal resistor of typical 60 kΩ
Apre = VQLA / VM = R29 / R26; in the basic application
R25 = R26 = 10 kΩ
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 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).
Larsen limiter current stabilizer (SIC) pin 17
A current reference is set by resistor R36 between SIC and
VSS. The preferred value is 120 kΩ. The internal reference
current is given by the following equation:
VBB
handbook, full pagewidth
C25
IDCA
R30
R29
R32
R33
DCA
C23
VM
R26
R25
LAI−
LAI+
−
−
C24
DTI
QLA
+
C22
+
VQLA
R27
VBB
R31
LLC
LARSEN
DETECTOR
VSS
R28
THL1
THL2
R35
R34
MGR037
Fig.8 Larsen limiter preamplifier and voltage/current converter.
March 1992
10
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).
handbook, halfpage
g
20 log
go
(dB)
f1
f2
f3
20 log f
0
6 dB per octave
12 dB per octave
The equation for DC current is:
R30
1
I DCA = ----------------------------- × V BB × ----------------------------R30 + R31
R32 + R33
18 dB per octave
The equation for AC current is:
V DTI
1
i DCA = ------------ for f > --- π R33 C25
2
R33
speech
Larsen
MGR038
In the basic application:
Fig.9 Third-order high-pass filter.
R30 = 100 kΩ, R31 = 220 kΩ, R33 = 500 Ω, R32 = 100 kΩ
and C25 = 330 nF
This results in IDCA = 11 µA and the equation:
i DCA
Where: g = ----------Vm
i DCA
----------- = 2 (mA/V)
V DTI
Larsen limiter capacitor (LLC) pin 12
High-pass filter
A 1 µF capacitor (C26) is connected externally between
VSS 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.
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
R30 × R31
f1 = ----------------------------- where R eq = ----------------------------2πR eg C24
R30 + R31
Larsen level limiter threshold (THL1 and THL2) pins
13 and 14
1
f2 = -----------------------------2πR33C24
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.
1
f3 = ------------------------------ = 1/(2πR25C22 )
2πR26C23
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
March 1992
A pre
g o = ---------R33
11
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.
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
(tLAa = 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 VSS. 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 VDTI2.
The second threshold level at DTI is determined by the
equation:
 1.25 I DCA 
- × 2 × R33 ( if f > f3 in Fig.9 )
V DTI2 =  ----------- – ----------R34
2 
The first threshold level at DTI is determined by the
equation:
 1.25 I DCA 
V DTI1 =  ----------- – ----------- × 2 × R33 ( if f > f3 in Fig.9 )
R25
2 
Where: IDCA = the DC current into DCA
With the component values given in Fig.16, IDCA = 11 µA
thus VDTI1 = 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 VLLC during charge is given in the equation:
Where: IDCA = the DC current into DCA
∆V LLC
1.25
- = ----------------------------- ( V ⁄ s )
S 1i = ---------------C26 × R36
∆τ
With the component values given in Fig.16,
VDTI2 = 6.9 mV.
With C26 = 1 µF and R36 = 120 kΩ this results in
S1i = 10 V/s.
The charge current in the Larsen mode is reduced to half
the charge current in the listen-in mode.
Discharge of the capacitor at LLC occurs when the signal
at DTI exceeds VDTI1, thus for a continuous signal at DTI
the attack delay time tad (see Fig.10) is determined by the
equation:
C26 × R36
t ad = -------------------------------------2 × ( 3 × k – 1)
The slope of VLLC during charge (see Fig.10) is given in the
equation:
∆V LLC
1.25
- = -------------------------------------- ( V ⁄ s )
S la = ---------------2 × C26 × R34
∆τ
Where: C26 = 1 µF and R36 = 100 kΩ, Sla = 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'
(tLAr). This time period is determined by capacitor C26
connected to LLC and resistor R36 connected to SIC.
Where k = t1 / T
The duty cycle is determined by the time in which the first
threshold level (VDTI1) 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
VDTI ≥ 100 mV(RMS)
March 1992
Where: C26 = 1 µF and R36 = 120 kΩ, tLAr = 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.
12
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
handbook, full pagewidth
TEA1085; TEA1085A
VDTI
slope Sli
slope Sla
0.63 V
VLLC
tad
tLAr
tLAa
1
0.5 V
0V
listen-in mode
Larsen mode
listen-in mode
MGR039
Where:
Gv
Change of receive gain = --------G vo
Nominal receive gain = 20 log Gvo = 35 dB
Fig.10 Dynamic behaviour of Larsen limiter (in open-loop condition).
handbook, full pagewidth
−VDTI
^
VDTI
VDTI1
t1
T
MGR040
 V DTI1 
arc sin  --------------- 
 Vˆ DTI 
k = 0.5 – ---------------------------------------π
Where:
t
k = ---1T
Fig.11 Definition of duty cycle k.
March 1992
13
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)
SYMBOL
PARAMETER
CONDITIONS
MIN.
MAX.
UNIT
positive supply voltage
VSUP
continuous
−
12
V
during switch-on or line interruption
−
13.2
V
−
28
V
with 12 Ω current
limiting resistor in
series with supply
repetitive supply voltage from 1 ms to 5 s
VSREF
supply reference voltage
VSS − 0.5
VSUP + 0.5
V
Vn
voltage on all other pins
VSS − 0.5
VBB + 0.5
V
ISUP
supply current
Ptot
TEA1085/TEA1085A
see Fig.12
−
120
mA
TEA1085T/TEA1085AT
see Fig.13
−
120
mA
Tamb = 75 °C;
Tj = 125 °C
total power dissipation
TEA1085/TEA1085A
−
1
W
TEA1085T/TEA1085AT
−
666
mW
°C
Tamb
operating ambient temperature range
−25
+75
Tstg
storage temperature range
−40
+125
°C
Tj
junction temperature
−
+125
°C
THERMAL RESISTANCE
SYMBOL
Rth j-a
PARAMETER
CONDITIONS
from junction to ambient in free air
TEA1085/TEA1085A
50 K/W
TEA1085T/TEA1085AT
note 1
Note
1. Device mounted on a glass epoxy board 40.1 × 19.1 × 1.5 mm.
March 1992
THERMAL
RESISTANCE
14
75 K/W
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
MGR041
MGR042
130
ISUP
130
ISUP
handbook, halfpage
handbook, halfpage
(mA)
(mA)
(1)
110
(1)
110
(2)
(2)
(3)
(3)
90
(4)
90
(5)
70
70
50
50
30
30
2
4
6
8
10
12
VSUP (V)
2
6
8
10
12
VSUP (V)
(1) Tamb = 35 °C; Ptot = 1.2 W.
(2) Tamb = 45 °C; Ptot = 1.07 W.
(3) Tamb = 55 °C; Ptot = 0.93 W.
(4) Tamb = 65 °C; Ptot = 0.8 W.
(5) Tamb = 75 °C; Ptot = 0.666 W.
(1) Tamb = 55 °C; Ptot = 1.4 W.
(2) Tamb = 65 °C; Ptot = 1.2 W.
(3) Tamb = 75 °C; Ptot = 1.0 W.
Fig.13 TEA1085T/TEA1085AT safe operating
area.
Fig.12 TEA1085/TEA1085A safe operating area.
March 1992
4
15
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
CHARACTERISTICS
VSREF = 4.2 V; VSS = 0 V; ISUP = 15 mA; VSUP = 0 V(RMS); f = 800 Hz; Tamb = 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
VSUP
−
VBB + 0.7
−
V
275
315
355
mV
3.4
3.6
3.8
V
−
10
−
mV
R38 = 39.2 kΩ between
pins VSS and VA;
VSREF = 5.2 V;
ISUP = 15 mA
4.2
4.45
4.7
V
no R38; ISUP = 15 mA
tbf
−0.2
tbf
V
minimum DC input voltage
VSUP-SREF internal reference voltage
VBB
∆VBB
∆VBB /∆T
stabilized supply voltage
no R38; ISUP = 15 mA
variation from
ISUP = 15 to 120 mA
variation with temperature
ISUP
minimum operating current
−
4.2
5.5
mA
THD
distortion of AC signal on SUP VSUP(RMS) = 1 V
−
0.3
−
%
Vno(RMS)
noise between SUP and VEE
−
−72
−
dBmp
current consumption in
power-down condition
PD = HIGH
ISUP
VSUP = 4.5 V
−
55
75
µA
IBB
VBB = 3.6 V
−
400
550
µA
single ended
7.5
9.5
11.5
kΩ
differential
15
19
23
kΩ
single ended
34
35
36
dB
BTL output
39.9
40.9
41.9
dB
single ended
−
+0.1
0.4
dB
BTL output
−
+0.2
0.6
dB
single ended
−
± 0.1
−
dB
BTL output
−
± 0.1
−
dB
single ended
−
± 0.4
−
dB
BTL output
−
± 0.5
−
dB
Loudspeaker amplifier inputs LSI1 and LSI2
|Zi|
Gv
∆Gv
∆Gv
∆Gv
March 1992
input impedance
voltage gain with 50 Ω load
variation with signal level
variation with frequency
referred to 1 kHz
variation with temperature
referred to 25 °C
ISUP = 15 mA;
Vi = 1.8 mV(RMS)
ISUP = 50 mA;
Vi = 1.8 mV(RMS) and
14 mV(RMS)
f = 300 Hz and 3400 Hz;
Vi = 1.8 mV(RMS)
Tamb = −25 to +75 °C
16
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
SYMBOL
PARAMETER
TEA1085; TEA1085A
CONDITIONS
MIN.
TYP.
MAX.
UNIT
Loudspeaker outputs QLS1 and QLS2
Vo(p-p)
output voltage (peak-to-peak
value)
single ended
bridge tied load
THD
total harmonic distortion
ISUP = 9 mA; note 1
1.2
1.45
−
V
ISUP = 17 mA; note 2
2.5
2.9
−
V
ISUP = 23.5 mA; note 2
2.5
2.9
−
V
ISUP = 32 mA; note 3
3.5
4.0
−
V
Vi = 22 mV(RMS)
ISUP = 9 mA
−
0.4
2
%
ISUP = 17 mA
−
0.7
2
%
ISUP = 23.5 mA
−
0.4
2
%
1.75
2.15
−
V
ISUP = 9 mA
−
0.5
10
%
ISUP = 17 mA
−
1.2
10
%
ISUP = 23.5 mA
−
0.6
10
%
ISUP = 17 mA
−
2
5
ms
current limiter
ISUP = 12 mA
−
500
tbf
ms
VBB limiter
ISUP = 9 mA
−
10
−
ms
single ended
bridge tied load
Vo(p-p)
Vi = 22 mV(RMS)
output voltage (peak-to-peak
value)
single ended
Vi = 22 mV(RMS)
ISUP = 17 mA;
VSUP − VEE = 1 V(RMS)
Dynamic limiter
THD
total harmonic distortion
single ended
bridge tied load
tatt
dynamic behaviour of limiter
attack time; Vi jumps from
10 mV(RMS) to 65 mV(RMS)
voltage limiter
Vi = 22 mV(RMS)
+10 dB
single ended load
trel
release time; Vi jumps from
65 mV(RMS) to 10 mV(RMS)
ISUP = 17 mA
tbf
75
tbf
ms
VBBO
threshold VBB limiter below
which gain reduction starts
ISUP = 9 mA
tbf
2.95
tbf
V
Vno(RMS)
noise output voltage
1 kΩ between inputs
LSI1, LSI2;
psophometrically
weighted (P53 curve)
single ended
−
170
−
µV
bridge tied load
−
350
−
µV
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
Logic gain control
∆Gv
March 1992
reduction of voltage gain
Vi = 1.8 mV(RMS)
17
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
SYMBOL
PARAMETER
TEA1085; TEA1085A
CONDITIONS
MIN.
TYP.
MAX.
UNIT
Larsen limiter preamplifier
operational amplifier
Gv0
open-loop gain
−
92
−
dB
fp1
1st pole
−
120
−
Hz
fp2
2nd pole
−
3.3
−
MHz
GB
unity gain bandwidth
−
4
−
MHz
51
52
53
dB
30
−
52
dB
Gv
voltage gain
Gv
gain adjustment range
f = 3 kHz;
R26 = 10 kΩ;
R29 = 4 MΩ
Larsen limiter detector
voltage to current convertor
VDCA-VDTI DC offset voltage
VBB − VDTI = 1 V
−25
1
+25
mV
Gv
voltage gain from DTI to DCA
VDTI = 100 mV(RMS);
f = 3 kHz
tbf
−0.8
tbf
dB
VTHL1
DC voltage at THL1
R35 = 51 kΩ
1.8
1.25
1.33
V
VTHL2
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
tLIr
listen-in release time
see Fig.15(a)
tbf
40
tbf
ms
tad
attack delay time
see Fig.15(b)
VDTI jumps from
0 to 100 mV (RMS value)
−
160
200
ms
VDTI jumps from
0 to 1 V (RMS value)
100
120
−
ms
−
20
tbf
ms
tbf
250
tbf
ms
1.75
1.9
2.0
V
0.59
0.63
0.68
V
60
tbf
tbf
dB
tLAa
Larsen attack time
see Fig.15(b);
VDTI = 100 mV(RMS)
tLAr
Larsen release time
see Fig.15(b)
VDTI jumps from
100 mV to 0 mV (RMS
value)
VLLC
DC voltage at LLC
−∆VLLC
reduction of VLLC to attack
Larsen mode
∆Gv
gain reduction
March 1992
VDTI = 0 V
VLLC = 0.7 V
18
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
SYMBOL
PARAMETER
TEA1085; TEA1085A
CONDITIONS
MIN.
TYP.
MAX.
UNIT
MUTE input; TEA1085
(toggle function, positive edge
triggered set-reset flip-flop)
VIL
LOW level input voltage
0
−
0.3
V
VIH
HIGH level input voltage
1.5
−
VBB + 0.4
V
IMUTE
input current
−
−22
−28
µA
tW
minimum input pulse width
−
50
−
µs
PR
minimum pulse repetition time
−
2
−
ms
tbf
2
tbf
V
60
100
−
dB
MUTE = LOW
VBB(MUTE) supply voltage below which
MUTE toggle is reset
∆Gv
reduction of gain from LSI1,
LSI2 to QLS1, QLS2
MUTE = ON
MUTE input; TEA1085A
VIL
LOW level input voltage
0
−
0.3
V
VIH
HIGH level input voltage
1.5
−
VBB + 0.4
V
IMUTE
input current
MUTE = HIGH
−
10
20
µA
∆Gv
reduction of gain from LSI1,
LSI2 to QLS1, QLS2
MUTE = HIGH
60
100
−
dB
0
−
0.3
V
Power down input
VIL
LOW level input voltage
VIH
HIGH level input voltage
IPD
input current
PD = HIGH
1.5
−
VBB + 0.4
V
−
2.3
2.8
µA
Logic inputs GSC1 and GSC2
VIL
LOW level input voltage
0
−
0.3
V
VIH
HIGH level input voltage
1.5
−
VBB + 0.4
V
IGSC
input current
−
6
8
µA
GSC = HIGH
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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(1)
R32
IIN
ISUP
(1)
(1)
C24
C25
(1)
A
ICC
VDTI
ILN
R1
R20
15
C21
1
4
2
3
R35
14
R34
13
C26
12
R33
16
15
R26
VBB
2
Vm
R27
R25 C22
7
3
Iline
5
TEA1060
C1
C23
9
19
8
R29
11
TEA1085
TEA1085A
VLSI
10
R28
6
6
Philips Semiconductors
R31
Listening-in circuit for line-powered
telephone sets
agewidth
March 1992
R30
VBB
C27
20
21
5
10
22
9
16
R5
1
18
C3
24
20
18
8
23
17
C28
C20
R9
7
R36
RL
50 Ω
MGR043
C31
(1)
(1)
VBB
for
for
TEA1085 TEA1085A
(1) To TEA1060 (SLPE)
V SUP – SREF
I LN = -----------------------------R20
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 ILN.
Fig.14 Test circuit.
Preliminary specification
The DC current is divided as follows:
V SUP – SREF
I SUP = I IN – -----------------------------R20
(1)
TEA1085; TEA1085A
VBB
(1)
(1)
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
Table 2
TEA1085; TEA1085A
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
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
330
nF
10
nF
Capacitor
C28
C31
March 1992
TEA1085 only
21
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
handbook, full pagewidth
VDTI
VDTI
200 ms
100 ms
VLLCO
0.63 V
VLLC
VLLC
tLIr
tad
MGR044
tLAr
tLAa
(b) Attack delay (tad), Larsen attack time (tLAa),
Larsen release time (tLAr);
VDTI = 100 mV(RMS) and 1 V(RMS); f = 3 kHz.
(a) Listen-in release time (tLIr);
VDTI = 100 mV(RMS); f = 3 kHz.
Fig.15 Test signals for Larsen level limiter.
March 1992
22
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(1)
R32
L1
R1
(1)
R20
15
C21
4
19
1
12
C1
(1)
8
2
3
R35
14
R34
13
C25
(1)
C26
12
C24
R33
16
15
R29
11
VBB
DP
23
LINE
TEA1060
DIALLER
TEA1085
TEA1085A
C2
5
to TEA1060
pins 7 and 8
R27
R25 C22
7
13
TONE
C23
R26
9
Philips Semiconductors
R31
Listening-in circuit for line-powered
telephone sets
APPLICATION INFORMATION
handbook, full pagewidth
March 1992
R30
VBB
10
R28
DP
DP
R24
C29
RV20
C27
5
21
C30
22
6
10
16
1
18
24
18
20
8
7
23
17
(1)
C3
R9
C11
C32
C20
C28
R38
R36
C31
(1)
interrupt
(1)
(1)
(1)
VBB
for
for
TEA1085 TEA1085A
(1) To TEA1060 (SLPE).
Fig.16 Basic application of TEA1085/TEA1085A and TEA1060.
(1)
Preliminary specification
VBB
(1)
MLA039
TEA1085; TEA1085A
DP
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
COMPONENT
CONDITION
VALUE
UNIT
Resistor
R20
R24
note 1
150
Ω
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
120
kΩ
1
kΩ
R36
RV20
note 1
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
TEA1085; TEA1085A
PACKAGE OUTLINES
seating plane
DIP24: plastic dual in-line package; 24 leads (600 mil)
SOT101-1
ME
D
A2
L
A
A1
c
e
Z
b1
w M
(e 1)
b
MH
13
24
pin 1 index
E
1
12
0
5
10 mm
scale
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
UNIT
A
max.
A1
min.
A2
max.
b
b1
c
D (1)
E (1)
e
e1
L
ME
MH
w
Z (1)
max.
mm
5.1
0.51
4.0
1.7
1.3
0.53
0.38
0.32
0.23
32.0
31.4
14.1
13.7
2.54
15.24
3.9
3.4
15.80
15.24
17.15
15.90
0.25
2.2
inches
0.20
0.020
0.16
0.066
0.051
0.021
0.015
0.013
0.009
1.26
1.24
0.56
0.54
0.10
0.60
0.15
0.13
0.62
0.60
0.68
0.63
0.01
0.087
Note
1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.
REFERENCES
OUTLINE
VERSION
IEC
JEDEC
SOT101-1
051G02
MO-015AD
March 1992
EIAJ
EUROPEAN
PROJECTION
ISSUE DATE
92-11-17
95-01-23
25
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
SO24: plastic small outline package; 24 leads; body width 7.5 mm
SOT137-1
D
E
A
X
c
HE
y
v M A
Z
13
24
Q
A2
A
(A 3)
A1
pin 1 index
θ
Lp
L
1
12
e
detail X
w M
bp
0
5
10 mm
scale
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
UNIT
A
max.
A1
A2
A3
bp
c
D (1)
E (1)
e
HE
L
Lp
Q
v
w
y
mm
2.65
0.30
0.10
2.45
2.25
0.25
0.49
0.36
0.32
0.23
15.6
15.2
7.6
7.4
1.27
10.65
10.00
1.4
1.1
0.4
1.1
1.0
0.25
0.25
0.1
0.9
0.4
inches
0.10
0.012 0.096
0.004 0.089
0.01
0.019 0.013
0.014 0.009
0.61
0.60
0.30
0.29
0.050
0.419
0.043
0.055
0.394
0.016
0.043
0.039
0.01
0.01
0.004
0.035
0.016
Z
(1)
θ
8o
0o
Note
1. Plastic or metal protrusions of 0.15 mm maximum per side are not included.
REFERENCES
OUTLINE
VERSION
IEC
JEDEC
SOT137-1
075E05
MS-013AD
March 1992
EIAJ
EUROPEAN
PROJECTION
ISSUE DATE
95-01-24
97-05-22
26
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
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.
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.
Preheating is necessary to dry the paste and evaporate
the binding agent. Preheating duration: 45 minutes at
45 °C.
WAVE SOLDERING
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).
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.
DIP
• The longitudinal axis of the package footprint must be
parallel to the solder flow.
SOLDERING 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 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.
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 (Tstg 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.
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.
REPAIRING SOLDERED JOINTS
A mildly-activated flux will eliminate the need for removal
of corrosive residues in most applications.
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.
REPAIRING 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.
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.
March 1992
27
Philips Semiconductors
Preliminary specification
Listening-in circuit for line-powered
telephone sets
TEA1085; TEA1085A
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
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© 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.
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Printed in The Netherlands
415102/00/02/pp32
Date of release: March 1992
Document order number:
9397 750 nnnnn