TEA1098 Philips Semiconductors, TEA1098 Datasheet - Page 12

• Manufacturer Part Number: TEA1098
• Description: Speech and handsfree IC
• Manufacturer: Philips Semiconductors

Philips Semiconductors
H
TXOUT
The TEA1098 has an asymmetrical handsfree microphone
input (TXIN) with an input resistance of 20 k .
The input DC bias is 0 V. The gain of the input stage varies
according to the TEA1098 mode. In Tx mode, it has
maximum gain; in Rx mode, it has minimum gain, and in
Idle mode, it is midway between maximum and minimum
gain.
1999 Oct 14
handbook, full pagewidth
handbook, full pagewidth
ANDSFREE MICROPHONE CHANNEL
Speech and handsfree IC
Pin numbers in parenthesis apply to the TEA1098H. Pin numbers not in parenthesis apply to the TEA1098TV.
AND
GNDTX (see Fig.8)
telephone
R MIC
line
V BB
C MIC
sidetone
(28)
31
:
PINS
TXIN
envelope
detector
Fig.7 Handsfree telephone set principles.
TXIN, GATX,
Fig.8 Handsfree microphone channel.
to
HYBRID
V
switch
voice
from
I
12
Switch-over from one mode to the other is smooth and
click-free. The output (TXOUT) is biased at a voltage of
two diodes and has a current capability of 20 A (RMS).
In Tx mode, the overall gain of the microphone amplifier
(from pins TXIN to TXOUT) can be adjusted from
0 up to 31 dB to suit specific application requirements.
The gain is proportional to the value of R
15.2 dB when R
the microphone input stage can accept signals of up to
18 mV (RMS) at 2% THD (room temperature).
I
CONTROL
DUPLEX
V
GNDTX
TXOUT
GATX
MGL342
GATX
30
(27)
29
(26)
32
(29)
is 30.1 k . Without output limitation,
R GATX
MGM299
coupling
acoustic
Product specification
GATX
TEA1098
and equals