tea1094t NXP Semiconductors, tea1094t Datasheet - Page 6

• Manufacturer Part Number: tea1094t
• Description: Hands Free Ic
• Manufacturer: NXP Semiconductors

Philips Semiconductors
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
1996 Jul 15
handbook, halfpage
Hands free IC
DLC/MUTER
Fig.2 Pin configuration (TEA1094).
STAB
SWR
RIN1
RIN2
GND
SWT
GAR
V BB
VOL
LSP
n.c.
n.c.
n.c.
10
11
12
13
14
1
2
3
4
5
6
7
8
9
TEA1094
MGE434
19
18
17
16
15
28
27
26
25
24
23
22
21
20
TSEN
TENV
TNOI
RSEN
RENV
RNOI
MIC
GAT
MOUT
MUTET
MICGND
n.c.
IDT
n.c.
6
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).
2. Receive mode (Rx mode).
3. Idle mode.
The difference between the maximum gain and minimum
gain is called the switching range.
handbook, halfpage
The gain of the microphone amplifier is at its maximum
and the gain of the loudspeaker amplifier is at its
minimum.
The gain of the loudspeaker amplifier is at its
maximum and the gain of the microphone amplifier is
at its minimum.
The gain of the amplifiers is halfway between their
maximum and minimum value.
DLC/MUTER
Fig.3 Pin configuration (TEA1094A).
STAB
SWR
RIN1
RIN2
GAR
GND
SWT
V BB
VOL
LSP
IDT
10
11
12
1
2
3
4
5
6
7
8
9
TEA1094; TEA1094A
TEA1094A
MGE435
15
14
13
19
18
17
16
24
23
22
21
20
Product specification
TSEN
TENV
TNOI
RSEN
RENV
RNOI
MIC
GAT
MOUT
MUTET
MICGND
PD