TEA1094T
DATA SH EET
Product specification
Supersedes data of 1996 Mar 11
File under Integrated Circuits, IC03
1996 Jul 15
INTEGRATED CIRCUITS
TEA1094; TEA1094A
Hands free IC
1996 Jul 15 2
Philips Semiconductors Product specification
Hands free IC TEA1094; TEA1094A
FEATURES
• Low power consumption
• Power-down function (TEA1094A only)
• Microphone channel with:
– externally adjustable gain
– microphone mute function.
• Loudspeaker channel with:
– externally adjustable gain
– dynamic limiter to prevent distortion
– rail-to-rail output stage for single-ended load drive
– logarithmic volume control via linear potentiometer
– loudspeaker mute function.
• Duplex controller consisting of:
– signal envelope and noise envelope monitors for both
channels with:
externally adjustable sensitivity
externally adjustable signal envelope time constant
externally adjustable noise envelope time constant
– decision logic with:
externally adjustable switch-over timing
externally adjustable idle mode timing
externally adjustable dial tone detector in
receive channel
– voice switch control with:
adjustable switching range
constant sum of gain during switching
constant sum of gain at different volume settings.
APPLICATIONS
• Mains, battery or line-powered telephone sets with
hands-free/listening-in functions
• Cordless telephones
• Answering machines
• Fax machines.
GENERAL DESCRIPTION
The TEA1094 and TEA1094A are bipolar circuits intended
for use in mains, battery or line-powered telephone sets,
cordless telephones, answering machines and Fax
machines. In conjunction with a member of the TEA106X,
TEA111X families of transmission circuits, the devices
offer a hands-free function. They incorporate a
microphone amplifier, a loudspeaker amplifier and a
duplex controller with signal and noise monitors on
both channels.
ORDERING INFORMATION
TYPE NUMBER
PACKAGE
NAME DESCRIPTION VERSION
TEA1094 DIP28 plastic dual in-line package; 28 leads (600 mil) SOT117-1
TEA1094A DIP24 plastic dual in-line package; 24 leads (600 mil) SOT101-1
TEA1094T SO28 plastic small outline package; 28 leads; body width 7.5 mm SOT136-1
TEA1094AT SO24 plastic small outline package; 24 leads; body width 7.5 mm SOT137-1
TEA1094AM SSOP24 plastic shrink small outline package; 24 leads; body width 5.3 mm SOT340-1
1996 Jul 15 3
Philips Semiconductors Product specification
Hands free IC TEA1094; TEA1094A
QUICK REFERENCE DATA
V
BB
=5V; V
GND
= 0 V; f = 1 kHz; T
amb
=25°C; MUTET = LOW; PD = LOW (TEA1094A only); R
L
=50Ω; R
VOL
=0Ω;
measured in test circuit of Fig.12; unless otherwise specified.
Note
1. Corresponds to 200 mW output power.
SYMBOL PARAMETER CONDITIONS MIN. TYP. MAX. UNIT
V
BB
supply voltage 3.3 − 12.0 V
I
BB
current consumption from pin V
BB
− 3.1 4.4 mA
G
vtx
voltage gain from pin MIC to
pin MOUT in transmit mode
V
MIC
= 1 mV (RMS);
R
GAT
= 30.1 kΩ
13 15.5 18 dB
∆G
vtxr
voltage gain adjustment with R
GAT
−15.5 − +15.5 dB
G
vrx
voltage gain in receive mode; the
difference between RIN1 and RIN2
to LSP
V
RIN
= 20 mV (RMS);
R
GAR
= 66.5 kΩ;
R
L
=50Ω
16 18.5 21 dB
∆G
vrxr
voltage gain adjustment with R
GAR
−18.5 − +14.5 dB
V
O(p-p)
output voltage (peak-to-peak value) V
RIN
= 150 mV (RMS);
R
GAR
= 374 kΩ;
R
L
=33Ω; V
BB
= 9.0 V;
note 1
− 7.5 − V
SWRA switching range − 40 − dB
∆SWRA switching range adjustment with R
SWR
referenced to R
SWR
= 365 kΩ
−40 − +12 dB
T
amb
operating ambient temperature −25 − +75 °C
1996 Jul 15 4
Philips Semiconductors Product specification
Hands free IC TEA1094; TEA1094A
BLOCK DIAGRAM
Fig.1 Block diagram.
handbook, full pagewidth
MGE436
LOG
BUFF
BUFF
LOG
BUFF
BUFF
LOGIC
V I
I V
VOICE
SWITCH
DYNAMIC
LIMITER
VOLUME
CONTROL
I V
V I
DLC/MUTER
LSP
GAR
RSEN
RENV
RNOI
TNOI
TENV
TSEN
MIC
MUTET
VOL
RIN2
RIN1
SWR
STAB
SWT
IDT
MICGND
MOUT
GAT
GND
V
BB
PD
(1)
10
(7)
(13)
19
(15)
22
(18)
28
(24)
27
(23)
26
(22)
23
(19)
24
(20)
25
(21)
5
(4)
6
(5)
1
(1)
8
(6)
21
(17)
20
(16)
18
(14)
16
(12)
14
(11)
13
(10)
12
(9)
2
(2)
2
3
(3)
11
(8)
13 mV
ATTENUATOR
13 mV
V
dt
V
ref
V
BB
V
BB
C
MIC
R
MIC
R
TSEN
C
TSEN
C
TENV
C
TNOI
C
RNOI
C
RENV
R
RSEN
C
RSEN
R
GAR
C
LSP
C
DLC
R
GAT
to TEA106x
R
IDT
C
SWT
R
STAB
R
SWR
from
TEA106x
R
VOL
LOUDSPEAKER CHANNEL
DUPLEX
CONTROLLER
MICROPHONE CHANNEL
TEA1094
TEA1094A
The pin numbers given in parenthesis are for the TEA1094A.
(1) TEA1094A only.
1996 Jul 15 5
Philips Semiconductors Product specification
Hands free IC TEA1094; TEA1094A
PINNING
SYMBOL
PINS
DESCRIPTION
TEA1094 TEA1094A
DLC/
MUTER 1 1 dynamic limiter timing adjustment; receiver channel mute input
RIN1 2 2 receiver amplifier input 1
RIN2 3 3 receiver amplifier input 2
n.c. 4 − not connected
GAR 5 4 receiver gain adjustment
LSP 6 5 loudspeaker amplifier output
n.c. 7 − not connected
GND 8 6 ground reference
n.c. 9 − not connected
V
BB
10 7 supply voltage
VOL 11 8 receiver volume adjustment
SWR 12 9 switching range adjustment
STAB 13 10 reference current adjustment
SWT 14 11 switch-over timing adjustment
n.c. 15 − not connected
IDT 16 12 idle mode timing adjustment
PD − 13 power-down input
n.c. 17 − not connected
MICGND 18 14 ground reference for the microphone amplifier
MUTET 19 15 transmit channel mute input
MOUT 20 16 microphone amplifier output
GAT 21 17 microphone gain adjustment
MIC 22 18 microphone input
RNOI 23 19 receive noise envelope timing adjustment
RENV 24 20 receive signal envelope timing adjustment
RSEN 25 21 receive signal envelope sensitivity adjustment
TNOI 26 22 transmit noise envelope timing adjustment
TENV 27 23 transmit signal envelope timing adjustment
TSEN 28 24 transmit signal envelope sensitivity adjustment
1996 Jul 15 6
Philips Semiconductors Product specification
Hands free IC TEA1094; TEA1094A
Fig.2 Pin configuration (TEA1094).
handbook, halfpage
DLC/MUTER
RIN1
RIN2
n.c.
GAR
LSP
n.c.
GND
n.c.
V
BB
VOL
SWR
STAB
SWT
TSEN
TENV
TNOI
RSEN
RNOI
MIC
RENV
GAT
MOUT
MUTET
MICGND
n.c.
IDT
n.c.
1
2
3
4
5
6
7
8
9
10
11
12
13
28
27
26
25
24
23
22
21
20
19
18
17
16
1514
TEA1094
MGE434
Fig.3 Pin configuration (TEA1094A).
handbook, halfpage
DLC/MUTER
RIN1
RIN2
GAR
LSP
GND
V
BB
VOL
SWR
STAB
SWT
IDT
TSEN
TENV
TNOI
RSEN
RNOI
MIC
RENV
GAT
MOUT
MUTET
MICGND
PD
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
TEA1094A
MGE435
FUNCTIONAL DESCRIPTION
General
The values given in the functional description are typical
values unless otherwise specified.
A principle diagram of the TEA106X is shown on the left
side of Fig.4. The TEA106X is a transmission circuit of the
TEA1060 family intended for hand-set operation.
It incorporates a receiving amplifier for the earpiece, a
transmit amplifier for the microphone and a hybrid.
For more details on the TEA1060 family, please refer to
“data Handbook IC03”
. The right side of Fig.4 shows a
principle diagram of the TEA1094 and TEA1094A,
hands-free add-on circuits with a microphone amplifier, a
loudspeaker amplifier and a duplex controller.
As can be seen from Fig.4, a loop is formed via the
sidetone network in the transmission circuit and the
acoustic coupling between loudspeaker and microphone
of the hands-free circuit. When this loop gain is greater
than 1, howling is introduced. In a full duplex application,
this would be the case.
The loop-gain has to be much lower than 1 and therefore
has to be decreased to avoid howling. This is achieved by
the duplex controller. The duplex controller of the
TEA1094 and TEA1094A detects which channel has the
‘largest’ signal and then controls the gain of the
microphone amplifier and the loudspeaker amplifier so that
the sum of the gains remains constant.
As a result, the circuit can be in three stable modes:
1. Transmit mode (Tx mode).
The gain of the microphone amplifier is at its maximum
and the gain of the loudspeaker amplifier is at its
minimum.
2. Receive mode (Rx mode).
The gain of the loudspeaker amplifier is at its
maximum and the gain of the microphone amplifier is
at its minimum.
3. Idle mode.
The gain of the amplifiers is halfway between their
maximum and minimum value.
The difference between the maximum gain and minimum
gain is called the switching range.
1996 Jul 15 7
Philips Semiconductors Product specification
Hands free IC TEA1094; TEA1094A
Fig.4 Hands-free telephone set principles.
handbook, full pagewidth
MGE438
DUPLEX
CONTROL
HYBRID
telephone
line
sidetone
acoustic
coupling
TEA106x
TEA1094
TEA1094A
Supply: pins V
BB
, GND and PD
The TEA1094 and TEA1094A must be supplied with an
external stabilized voltage source between pins V
BB
and
GND. In the idle mode, without any signal, the internal
supply current is 3.1 mA at V
BB
=5V.
To reduce the current consumption during pulse dialling or
register recall (flash), the TEA1094A is provided with a
power-down (PD) input. When the voltage on PD is HIGH
the current consumption from V
BB
is 180 µA.
Microphone channel: pins MIC, GAT, MOUT, MICGND
and MUTET (see Fig.5)
The TEA1094 and TEA1094A have an asymmetrical
microphone input MIC with an input resistance of 20 kΩ.
The gain of the input stage varies according to the mode
of the TEA1094 and TEA1094A. In the transmit mode, the
gain is at its maximum; in the receive mode, it is at its
minimum and in the idle mode, it is halfway between
maximum and minimum.
Switch-over from one mode to the other is smooth and
click-free. The output capability at pin MOUT is
20 µA (RMS).
In the transmit mode, the overall gain of the microphone
amplifier (from pins MIC to MOUT) can be adjusted from
0 dB up to 31 dB to suit specific application requirements.
The gain is proportional to the value of R
GAT
and equals
15.5 dB with R
GAT
= 30.1 kΩ.
A capacitor must be connected in parallel with R
GAT
to
ensure stability of the microphone amplifier. Together with
R
GAT
, it also provides a first-order low-pass filter.
By applying a HIGH level on pin MUTET, the microphone
amplifier is muted and the TEA1094 and TEA1094A are
automatically forced into the receive mode.
1996 Jul 15 8
Philips Semiconductors Product specification
Hands free IC TEA1094; TEA1094A
Fig.5 Microphone channel.
handbook, full pagewidth
MGD343
V I I V
C
MIC
V
BB
R
MIC
MUTET
MIC
from
voice
switch
to
envelope
detector
MICGND
MOUT
GAT 21
(17)
19
(15)
22
(18)
20
(16)
18
(14)
to TEA106X
R
GAT
C
GAT
to
logic
The pin numbers given in parenthesis refer to the TEA1094A.
Loudspeaker channel
Fig.6 Loudspeaker channel.
handbook, full pagewidth
MGE437
DYNAMIC
LIMITER
VOLUME
CONTROL
I V
V I
DLC/MUTER
LSP
GAR
VOL
RIN2
RIN1
5
(4)
6
(5)
1
(1)
2
2
(2)
3
(3)
11
(8)
V
BB
R
GAR
C
GAR
C
LSP
C
DLC
from
TEA106x
R
VOL
to
logic
to/from
voice switch
to
envelope
detector
The pin numbers given in parenthesis refer to the TEA1094A.
1996 Jul 15 9
Philips Semiconductors Product specification
Hands free IC TEA1094; TEA1094A
LOUDSPEAKER AMPLIFIER: PINS RIN1, RIN2, GAR AND LSP
The TEA1094 and TEA1094A have symmetrical inputs for
the loudspeaker amplifier with an input resistance of 40 kΩ
between RIN1 and RIN2 (2 × 20 kΩ). The input stage can
accommodate signals up to 390 mV (RMS) at room
temperature for 2% of total harmonic distortion (THD).
The gain of the input stage varies according to the mode
of the TEA1094 and TEA1094A. In the receive mode, the
gain is at its maximum; in the transmit mode, it is at its
minimum and in the idle mode, it is halfway between
maximum and minimum. Switch-over from one mode to
the other is smooth and click-free. The rail-to-rail output
stage is designed to power a loudspeaker connected as a
single-ended load (between LSP and GND).
In the receive mode, the overall gain of the loudspeaker
amplifier can be adjusted from 0 dB up to 33 dB to suit
specific application requirements. The gain from
RIN1 and RIN2 to LSP is proportional to the value of R
GAR
and equals 18.5 dB with R
GAR
= 66.5 kΩ. A capacitor
connected in parallel with R
GAR
can be used to provide a
first-order low-pass filter.
V
OLUME CONTROL: PIN VOL
The loudspeaker amplifier gain can be adjusted with the
potentiometer R
VOL
. A linear potentiometer can be used to
obtain logarithmic control of the gain at the loudspeaker
amplifier. Each 950 Ω increase of R
VOL
results in a gain
loss of 3 dB. The maximum gain reduction with the volume
control is internally limited to the switching range.
D
YNAMIC LIMITER: PIN DLC/MUTER
The dynamic limiter of the TEA1094 and TEA1094A
prevents clipping of the loudspeaker output stage and
protects the operation of the circuit when the supply
voltage at V
BB
falls below 2.9 V.
Hard clipping of the loudspeaker output stage is prevented
by rapidly reducing the gain when the output stage starts
to saturate. The time in which gain reduction is effected
(clipping attack time) is approximately a few milliseconds.
The circuit stays in the reduced gain mode until the peaks
of the loudspeaker signals no longer cause saturation.
The gain of the loudspeaker amplifier then returns to its
normal value within the clipping release time (typically
250 ms). Both attack and release times are proportional to
the value of the capacitor C
DLC
. The total harmonic
distortion of the loudspeaker output stage, in reduced gain
mode, stays below 5% up to 10 dB (minimum) of input
voltage overdrive [providing V
RIN
is below 390 mV (RMS)].
When the supply voltage drops below an internal threshold
voltage of 2.9 V, the gain of the loudspeaker amplifier is
rapidly reduced (approximately 1 ms). When the supply
voltage exceeds 2.9 V, the gain of the loudspeaker
amplifier is increased again.
By forcing a level lower than 0.2 V on pin DLC/
MUTER, the
loudspeaker amplifier is muted and the TEA1094
(TEA1094A) is automatically forced into the transmit
mode.
Duplex controller
S
IGNAL AND NOISE ENVELOPE DETECTORS: PINS TSEN,
TENV, TNOI, RSEN, RENV
AND RNOI
The signal envelopes are used to monitor the signal level
strength in both channels. The noise envelopes are used
to monitor background noise in both channels. The signal
and noise envelopes provide inputs for the decision logic.
The signal and noise envelope detectors are shown in
Fig.7.
For the transmit channel, the input signal at MIC is 40 dB
amplified to TSEN. For the receive channel, the differential
signal between RIN1 and RIN2 is 0 dB amplified to RSEN.
The signals from TSEN and RSEN are logarithmically
compressed and buffered to TENV and RENV
respectively. The sensitivity of the envelope detectors is
set with R
TSEN
and R
RSEN
. The capacitors connected in
series with the two resistors block any DC component and
form a first-order high-pass filter. In the basic application,
see Fig.13, it is assumed that V
MIC
= 1 mV (RMS) and
V
RIN
= 100 mV (RMS) nominal and both R
TSEN
and R
RSEN
have a value of 10 kΩ. With the value of C
TSEN
and C
RSEN
at 100 nF, the cut-off frequency is at 160 Hz.
The buffer amplifiers leading the compressed signals to
TENV and RENV have a maximum source current of
120 µA and a maximum sink current of 1 µA. Together with
the capacitor C
TENV
and C
RENV
, the timing of the signal
envelope monitors can be set. In the basic application, the
value of both capacitors is 470 nF. Because of the
logarithmic compression, each 6 dB signal increase
means 18 mV increase of the voltage on the envelopes
TENV or RENV at room temperature. Thus, timings can be
expressed in dB/ms. At room temperature, the 120 µA
sourced current corresponds to a maximum rise-slope of
the signal envelope of 85 dB/ms. This is sufficient to track
normal speech signals. The 1 µA current sunk by TENV or
RENV corresponds to a maximum fall-slope of 0.7 dB/ms.
This is sufficient for a smooth envelope and also eliminates
the effect of echoes on switching behaviour.
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