參數(shù)資料
型號： TEA1098ATV
廠商： NXP SEMICONDUCTORS
元件分類： 無繩電話/電話
英文描述： Speech and handsfree IC
中文描述： TELEPHONE SPEECH CKT, PDSO40
封裝： PLASTIC, VSOP-40
文件頁數(shù)： 14/40頁
文件大?。?/td> 185K
代理商： TEA1098ATV
2000 Mar 21
14
Philips Semiconductors
Preliminary specification
Speech and handsfree IC
TEA1098A
Loudspeaker amplifier (pins HFRX, GALS and LSAO)
The TEA1098A has an asymmetrical input for the
loudspeaker amplifier with an input resistance of 20 k
between pins HFRX and GND. It is biased at two diodes
voltage. Without limitation from the output, the input stage
can accommodate signals up to 580 mV (RMS) at room
temperature for 2% of THD.
The gain of the input stage varies according to the mode
of the TEA1098A. 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 pins LSAO and GND).
In the receive mode, the overall gain of the loudspeaker
amplifier can be adjusted from 0 dB up to 35 dB to suit
specific application requirements. The gain from HFRX to
LSAO is proportional to the value of R
GALS
and equals
28 dB with R
GALS
= 255 k
. A capacitor connected in
parallel with R
GALS
is recommended and provides a
first-order low-pass filter.
Digital volume control (pins LVCI and EVCI)
The loudspeaker amplifier gain can be adjusted
(attenuated) with the LVCI logic input (as MSB) and the
4-level input EVCI (as LSBs). This combination provides
8 steps of
4 dB which applies in all handsfree receive
modes.
Dynamic limiter (pin DLC)
The dynamic limiter of the TEA1098A prevents clipping of
the loudspeaker output stage and protects the operation of
the circuit when the supply voltage at V
BB
falls below 2.7 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
oftheloudspeakersignalsnolongercausesaturation.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 2% up to 10 dB (minimum) of input voltage
overdrive [providing V
HFRX
is below 580 mV (RMS)].
Whenthesupplyvoltagedropsbelowaninternalthreshold
voltage of 2.7 V, the gain of the loudspeaker amplifier is
rapidly reduced (approximately 1 ms). When the supply
voltage exceeds 2.7 V, the gain of the loudspeaker
amplifier is increased again.
By forcing a level lower than 0.2 V on pin DLC, the
loudspeaker amplifier is muted and the TEA1098A is
automatically forced into the transmit mode.
D
UPLEX CONTROLLER
Signal 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 illustrated in
Fig.10.
For the transmit channel, the input signal at pin TXI is
40 dB amplified to TSEN. For the receive channel, the
input signal at pin HFRX 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.18) it is assumed that V
TXI
= 1 mV (RMS) and
V
HFRX
= 100 mV (RMS) nominal and both R
TSEN
and
R
RSEN
have a value of 10 k
. With the value of C
TSEN
and
C
RSEN
at 100 nF, the cut-off frequency is at 160 Hz.
The buffer amplifiers feeding the compressed signals to
pins TENV and RENV have a maximum source current of
120
μ
A and a maximum sink current of 1
μ
A. Capacitors
C
TENV
and C
RENV
set the timing of the signal envelope
monitors. 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
μ
A 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
μ
A 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.
相關PDF資料
PDF描述
TEA1507 GreenChipII SMPS control IC
TEA1507P GreenChipII SMPS control IC
TEA1533P GreenChip SMPS control IC
TEA1533T GreenChipTMII SMPS control IC
TEA1541 SMPS control IC with synchronization function
相關代理商/技術參數(shù)
參數(shù)描述
TEA1098H 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Speech and handsfree IC
TEA1098TV 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Speech and handsfree IC
TEA1098UH 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Speech and handsfree IC
TEA1099 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Speech and handsfree IC with auxiliary inputs/outputs and analog multiplexer
TEA1099H 制造商:PHILIPS 制造商全稱:NXP Semiconductors 功能描述:Speech and handsfree IC with auxiliary inputs/outputs and analog multiplexer
發(fā)布緊急采購，3分鐘左右您將得到回復。

采購需求

(若只采購一條型號，填寫一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

發(fā)布成功！您可以繼續(xù)發(fā)布采購。也可以進入我的后臺，查看報價

*型號 *數(shù)量 廠商 批號 封裝
添加更多采購

我的聯(lián)系方式

*
*
*