TEA1111AT/C2,518 NXP Semiconductors, TEA1111AT/C2,518 Datasheet - Page 10

• Manufacturer Part Number: TEA1111AT/C2,518
• Description: Speech Network Advanced 45.2dB 16-Pin SO T/R
• Manufacturer: NXP Semiconductors

Specifications of TEA1111AT/C2,518

• Package: 16SO
• Applications: Answering Machines|Cordless Telephones|Fax Machines|Telephone Sets
• Maximum Receiver Gain: 28.4 dB
• Maximum Transmitter Gain: 45.2 dB
• Typical Supply Current: 1.15|-1 mA
• Typical Operating Supply Voltage: 3.25|3.3 V

Philips Semiconductors
The output voltage of the earpiece amplifier is specified for
continuous wave drive. The maximum output swing
depends on the DC line voltage, the R
current consumption of the circuit, the I
consumption of the peripheral circuits and the load
impedance.
Automatic gain control is provided on this amplifier for line
loss compensation.
V
A positive DC voltage applied to pin VCI allows the gain of
the earpiece amplifier to be increased in steps of 4.85 dB.
The volume control range is 27.4 to 41.9 dB (14.5 dB
typical). A proportional voltage decoder at pin VCI defines
a gain of 27.4 dB when V
41.9 dB when V
The intermediate steps correspond to:
and
Automatic gain control (pin AGC)
The TEA1111A performs automatic line loss
compensation. The automatic gain control varies the gain
of the microphone amplifier and the gain of the receive
amplifier in accordance with the DC line current.
The control range is 6.0 dB (which corresponds
approximately to a line length of 5 km for a 0.5 mm
diameter twisted-pair copper cable with a DC resistance of
176 /km and an average attenuation of 1.2 dB/km).
The IC can be used with different configurations of feeding
bridge (supply voltage and bridge resistance) by
connecting an external resistor R
and V
currents to be increased (the ratio between I
not affected by the resistor). The AGC function is disabled
when pin AGC is left open circuit.
Mute function (pin MUTE)
The mute function performs the switching between the
speech mode and the dialling mode.
When MUTE is LOW, the DTMF input is enabled and the
microphone and receive amplifier inputs are disabled.
In this mode, the DTMF tones are sent to the receive
output at a low level (confidence tone).
2000 Feb 18
OLUME CONTROL
Speech circuit with dialler interface, regulated
supply and earpiece volume control
V
EE
VCI
. This resistor enables the I
=
2
-- - V
3
DD
VCI
(
PIN
.
equals V
VCI)
VCI
DD
equals V
.
AGC
start
between pins AGC
EE
CC
P
V
and I
and a gain of
VCI
current
resistor, the I
start
stop
=
1
-- - V
3
and I
line
DD
stop
CC
is
10
When MUTE is HIGH, the microphone and receiving
amplifiers inputs are enabled while the DTMF input is
disabled. The MUTE input is provided with an internal
pull-up current source to V
Sidetone suppression
The TEA1111A anti-sidetone network comprising
R
suppresses the transmitted signal in the earpiece.
Maximum compensation is obtained when the following
conditions are fulfilled:
The scale factor k is chosen to meet the compatibility with
a standard capacitor from the E6 or E12 range for Z
In practice, Z
the line length. Therefore, the value of Z
average line length, which gives satisfactory sidetone
suppression with short and long lines. The suppression
also depends on the accuracy of the match between Z
and the impedance of the average line.
The anti-sidetone network for the TEA1111A attenuates
the receive signal from the line by 32 dB before it enters
the receive stage. The attenuation is almost constant over
the whole audio frequency range.
A Wheatstone bridge configuration (see Fig.11) may also
be used.
More information on the balancing of an anti-sidetone
bridge can be obtained in our publication “Semiconductors
for Wired Telecom Systems; Applications Handbook
IC03b” .
For ordering information, please contact the Philips
Semiconductors sales office.
CC
Z
k
R
bal
// Z
=
SLPE
=
line
R
------------------------------------------------------------
ast2
k
, R
R
R
line
ast1
Z
ast1
ast1
line
varies considerably with the line type and
R
, R
ast3
=
ast2
R
R
+
SLPE
, R
CC
R
SLPE
ast3
DD
R
, R
.
ast2
SLPE
+
R
and Z
Product specification
ast3
TEA1111A
bal
should be for an
bal
(see Fig.10)
bal
.
bal