TEA1095T NXP Semiconductors, TEA1095T Datasheet - Page 9

• Manufacturer Part Number: TEA1095T
• Manufacturer: NXP Semiconductors

Specifications of TEA1095T

• Operating Temp Range: -25C to 75C
• Package Type: SO
• Pin Count: 24
• Operating Temperature Classification: Commercial
• Mounting: Surface Mount
• Lead Free Status / Rohs Status: Compliant

Philips Semiconductors
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.12), it is assumed
that V
nominal and both R
With the value of C
frequency is at 160 Hz.
The buffer amplifiers leading the compressed signals to
TENV and RENV have a maximum source current of
120 A and a maximum sink current of 1 A. Together with
the capacitors C
envelope monitors can be set. 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 A
sourced current corresponds to a maximum rise-slope of
the signal envelope of 85 dB/ms. This is enough to track
normal speech signals. The 1 A current sunk by TENV or
1997 Nov 25
handbook, full pagewidth
Voice switched speakerphone IC
TXIN
= 1 mV (RMS) and V
DUPLEX CONTROLLER
from
transmit
amplifier
TENV
TSEN
TSEN
and C
TSEN
and R
and C
LOG
RENV
RSEN
RSEN
R TSEN
C TSEN
RXIN
, the timing of the signal
have a value of 10 k .
at 100 nF, the cut-off
= 100 mV (RMS)
Fig.6 Signal and noise envelope detectors.
TENV
C TENV
to logic
TNOI
C TNOI
9
RENV corresponds to a maximum fall-slope of 0.7 dB/ms.
This is enough for a smooth envelope and also eliminates
the effect of echoes on switching behaviour.
To determine the noise level, the signal on TENV and
RENV are buffered to TNOI and RNOI. These buffers have
a maximum source current of 1 A and a maximum sink
current of 120 A. Together with the capacitors C
C
Fig.12, 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. 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.7.
from
receiver
amplifier
RNOI
, the timing can be set. In the basic application of
RSEN
LOG
R RSEN
C RSEN
RENV
C RENV
to logic
RNOI
Product specification
TEA1095
C RNOI
MBG355
TNOI
and