TEA1093T Philips Semiconductors, TEA1093T Datasheet - Page 13

• Manufacturer Part Number: TEA1093T
• Description: Hands-free IC
• Manufacturer: Philips Semiconductors

Philips Semiconductors
1996 Feb 09
G vtx, G vrx
(10 dB/div)
handbook, halfpage
Hands-free IC
(1) c - constant.
volume
control
from
400
Fig.12 Switch-over behaviour.
Tx mode
DUPLEX CONTROLLER
microphone
amplifier
G vtx
VOICE SWITCH
Fig.11 Voice-switch.
to
G vtx
G vrx
loudspeaker
200
amplifier
G vrx
to
SWT
from
C
idle
mode
(1)
0
STAB
SWR
MGD225
V SWT
200
(10)
(9)
12
Rx mode
13
V IDT (mV)
MBG351
R STAB
R SWR
400
R VOL
5700
3800
1900
0
0
1900
3800
5700
( )
13
In the transmit mode, the gain of the microphone amplifier
is at its maximum and the gain of the loudspeaker amplifier
is at its minimum. In the receive mode, the opposite
applies. In the idle mode, both microphone and
loudspeaker amplifier gains are halfway. The difference
between maximum and minimum is the so called switching
range. This range is determined by the ratio of R
R
should be 3.65 k and sets an internally used reference
current. In the basic application diagram given in Fig.16,
R
of 40 dB. The switch-over behaviour is illustrated in Fig.12.
In the receive mode, the gain of the loudspeaker amplifier
can be reduced using the volume control. Since the
voice-switch keeps the sum of the gains constant, the gain
of the microphone amplifier is increased at the same time
(see dashed curves in Fig.12). In the transmit mode,
however, the volume control has no influence on the gain
of the microphone amplifier or the gain of the loudspeaker
amplifier. Consequently, the switching range is reduced
when the volume is reduced. At maximum reduction of
volume, the switching range becomes 0 dB.
STAB
SWR
is 365 k which results in a switching range
and is adjustable between 0 and 52 dB. R
Product specification
TEA1093
SWR
STAB
and