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PDF TEA1098 Data sheet ( Hoja de datos )
| Número de pieza | TEA1098 | |
| Descripción | Speech and handsfree IC | |
| Fabricantes | NXP Semiconductors | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de TEA1098 (archivo pdf) en la parte inferior de esta página. Total 30 Páginas | ||
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INTEGRATED CIRCUITS
DATA SHEET
TEA1098
Speech and handsfree IC
Product specification
Supersedes data of 1999 May 20
File under Integrated Circuits, IC03
1999 Oct 14
1 page  
Philips Semiconductors
Speech and handsfree IC
Product specification
TEA1098
PINNING
SYMBOL
PD
MUTE
n.c.
n.c.
n.c.
n.c.
n.c.
HFRX
TNOI
TENV
TSEN
RNOI
RSEN
RENV
DLC
n.c.
VBB
GALS
LSAO
GND
SLPE
LN
REG
IR
AGC
VDD
MICS
STAB
SWR
VOL
SWT
IDT
TXOUT
GATX
TXIN
GNDTX
MIC−
MIC+
PIN
TEA1098TV TEA1098H
1 38
2 39
3 40
4 41
− 42
− 43
− 44
51
62
73
84
95
10 6
11 7
12 8
−9
13 10
14 11
15 12
16 13
17 14
18 15
19 16
20 17
21 18
22 19
23 20
24 21
25 22
26 23
27 24
28 25
29 26
30 27
31 28
32 29
33 30
34 31
PAD
TEA1098UH
DESCRIPTION
41 power-down input (active LOW)
42 logic input (active LOW)
43 not connected
44 not connected
45 not connected
46 not connected
47 not connected
1 receive input for loudspeaker amplifier
2 transmit noise envelope timing adjustment
3 transmit signal envelope timing adjustment
4 transmit signal envelope sensitivity adjustment
5 receive noise envelope timing adjustment
6 receive signal envelope sensitivity adjustment
7 receive signal envelope timing adjustment
8 dynamic limiter capacitor for the loudspeaker amplifier
9 and 13 not connected
10 stabilized supply for internal circuitry
11 loudspeaker amplifier gain adjustment
12 loudspeaker amplifier output
14 and 15 ground reference
16 line current sense
17 positive line terminal
18 line voltage regulator decoupling
19 receive amplifier input
20 automatic gain control/line loss compensation
21 3.35 V regulated voltage supply for microcontrollers
22 microphone supply
23 reference current adjustment
24 switching range adjustment
25 loudspeaker volume adjustment
26 switch-over timing adjustment
27 Idle mode timing adjustment
28 HF microphone amplifier output
29 HF microphone amplifier gain adjustment
30 HF microphone amplifier input
31 to 32 ground reference for microphone amplifiers
33 negative HS microphone amplifier input
34 positive HS microphone amplifier input
1999 Oct 14
5
5 Page 
Philips Semiconductors
Speech and handsfree IC
Product specification
TEA1098
HANDSFREE TRANSMIT AMPLIFIER (PINS HFTX AND LN)
The TEA1098 has an asymmetrical HFTX input, which is
mainly intended for use in combination with the TXOUT
output. The input impedance between HFTX and GND is
typically 20 kΩ. The voltage gain between
pins HFTX and LN is set to 34.7 dB. Without output
limitation, the input stage can accept signals of up to
95 mV (RMS) at 2% THD (room temperature). The HFTX
input is biased at a voltage of two diodes.
Automatic gain control is provided for line loss
compensation.
Receive channels (pins IR, RECO, GARX and QR)
RX AMPLIFIER (PINS IR AND RECO)
The receive amplifier has one input (IR) which is
referenced to the line. The input impedance between pins
IR and LN is typically 20 kΩ and the DC bias between
these pins is equal to the voltage of one diode. The gain
between pins IR (referenced to LN) and RECO is typically
29.7 dB. Without output limitation, the input stage can
accept signals of up to 50 mV (RMS) at 2% THD (room
temperature).
The receive amplifier has a rail-to-rail output (RECO),
which is designed for use with high ohmic (real) loads of
more than 5 kΩ. This output is biased at a voltage of two
diodes.
Automatic gain control is provided for line loss
compensation.
EARPIECE AMPLIFIER (PINS GARX AND QR)
The earpiece amplifier is an operational amplifier which
has an output (QR) and an inverting input (GARX).
Its input signal is fed by a decoupling capacitor from the
receive amplifier output (RECO) to two resistors which set
the required gain or attenuation from −3 to +15 dB
compared to the receive gain.
Two external capacitors CGAR (connected between GAR
and QR) and CGARS (connected between GAR and GND)
ensure stability. The CGAR capacitor provides a first-order
low-pass filter. The cut-off frequency corresponds to the
time constant CGAR × Re2. The relationship
CGARS ≥ 10 × CGAR must be satisfied.
The earpiece amplifier has a rail-to-rail output (QR) biased
at a voltage of two diodes. It is designed for use with low
ohmic (real) loads of 150 Ω, or capacitive loads of 100 nF
in series with 100 Ω.
AGC (pin AGC)
The TEA1098 performs automatic line loss compensation,
which fits well with the true line attenuation. The automatic
gain control varies the gain of some transmit and receive
amplifiers in accordance with the DC line current.
The control range is 6.45 dB for Gv(MIC-LN) and Gv(IR-RECO),
and 6.8 dB for Gv(HFTX-LN), which corresponds
approximately to a line length of 5.5 km for a 0.5 mm
twisted-pair copper cable.
To enable this gain control, the pin AGC must be shorted
to pin LN. The start current for compensation corresponds
to a line current of typically 23 mA and a stop current of
57 mA. The start current can be increased by connecting
an external resistor between pins AGC and LN. It can be
increased by up to 40 mA (using a resistor of typically
80 kΩ). The start and stop current will be maintained at a
ratio of 2.5. By leaving the AGC pin open, the gain control
is disabled and no line loss compensation occurs.
Handsfree application
Figure 7 shows a loop is formed by the sidetone network
in the line interface section, and by the acoustic coupling
between loudspeaker and microphone in the handsfree
section. A loop-gain of greater than 1 causes howl.
To prevent howl in full duplex applications, the loop-gain
must be set much lower than 1. This is achieved by the
duplex controller which detects the channel with the
‘largest’ signal and controls the gains of the microphone
and the loudspeaker amplifiers so that the sum of their
gains remains constant.
Therefore in the handsfree application, the circuit can have
three stable modes:
1. Transmit mode (Tx mode).
The microphone amplifier is at maximum gain, and the
loudspeaker amplifier is at minimum gain.
2. Receive mode (Rx mode).
The microphone amplifier is at minimum gain, and the
loudspeaker amplifier is at maximum gain.
3. Idle mode.
The microphone amplifier and the loudspeaker
amplifier are both midway between maximum and
minimum gain.
The difference between the maximum and minimum gain
is called the switching range.
1999 Oct 14
11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet TEA1098.PDF ] | |
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