TEA1098ATV PHILIPS [NXP Semiconductors], TEA1098ATV Datasheet - Page 15

• Manufacturer Part Number: TEA1098ATV
• Description: Speech and handsfree IC
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
To determine the noise level, the signals on pins TENV
and RENV are buffered to pins TNOI and RNOI. These
buffers have a maximum source current of 1 A and a
maximum sink current of 120 A. Capacitors C
C
the value of both capacitors is 4.7 F. At room
temperature, the 1 A sourced current corresponds to a
maximum rise-slope of the noise envelope of
approximately 0.07 dB/ms.
2000 Mar 21
handbook, full pagewidth
RNOI
Speech and handsfree IC
handbook, full pagewidth
set the timing. In the basic application, see Fig.18,
from
microphone
amplifier
SIGNAL ENVELOPE
DUPLEX CONTROLLER
NOISE ENVELOPE
INPUT SIGNAL
A: 85 dB/ms
B: 0.7 dB/ms
B: 0.7 dB/ms
C: 0.07 dB/ms
LOG
9 (4)
TSEN
R TSEN
C TSEN
C
Fig.11 Signal and noise envelope waveforms.
Fig.10 Signal and noise envelope detectors.
A
4 mV (RMS)
8 (3)
TENV
C TENV
36 mV
TNOI
to logic
36 mV
and
7 (2)
TNOI
C TNOI
15
from
loudspeaker
amplifier
This is small enough to track background noise and not to
be influenced by speech bursts. The 120 A current that is
sunk corresponds to a maximum fall-slope of
approximately 8.5 dB/ms. However, during the decrease
of the signal envelope, the noise envelope tracks the
signal envelope so it will never fall faster than
approximately 0.7 dB/ms. The behaviour of the signal
envelope and noise envelope monitors is illustrated in
Fig.11.
B
B
1 mV (RMS)
LOG
11 (6)
RSEN
R RSEN
C RSEN
C
A
12 (7)
RENV
MBG354
C RENV
time
B
B
to logic
Preliminary specification
TEA1098A
10 (5)
RNOI
FCA152
C RNOI