TEA1113 Philips Semiconductors, TEA1113 Datasheet - Page 7

• Manufacturer Part Number: TEA1113
• Description: Low voltage versatile telephone transmission circuit with dialler interface
• Manufacturer: Philips Semiconductors

Philips Semiconductors
on the line signal remain below the threshold level.
The microphone gain then returns to its nominal value after
a time determined by the capacitor C
The maximum output swing on the line depends on the DC
voltage setting (V
automatically adapted.
A LOW level on pin DLS/MMUTE inhibits the microphone
inputs MIC+ and MIC without affecting the DTMF and
receiving inputs. Removing the LOW level from pin
DLS/MMUTE provides the normal function of the
microphone amplifier after a short time which is
determined by capacitor C
capacitor at 470 nF, the release time is in the order of a
few tenths of a millisecond. The microphone mute function
can be realized by a simple switch as illustrated in Fig.9.
Receiving amplifier (pins IR, GAR and QR)
The receiving amplifier has one input (IR) and one output
(QR). The input impedance between pin IR and pin V
20 k . The voltage gain from pin IR to pin QR is fixed to
31.3 dB (typ). The gain can be decreased by connecting
an external resistor R
adjustment range is 12 dB. Two external capacitors C
(connected between GAR and QR) and C
between GAR and V
capacitor provides a first-order low-pass filter. The cut-off
frequency corresponds to the time constant
C
which sets the gain with a typical value of 100 k .
The relationship C
ensure stability.
The output voltage of the receiving 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.
Automatic gain control (pin AGC)
The TEA1113 performs automatic line loss compensation.
The automatic gain control varies the gain of the
microphone amplifier and the gain of the receiving
amplifier in accordance with the DC line current.
The control range is 5.8 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).
1997 Mar 27
GAR
Low voltage versatile telephone
transmission circuit with dialler interface
(R
GARint
// R
ref
GARS
). The internal threshold level is
GAR
EE
GAR
) ensure stability. The C
). R
= 10
between pins GAR and QR; the
DLS
GARint
. With the value of the
C
GAR
is the internal resistor
must be fulfilled to
DLS
CC
p
current
(release time).
GARS
resistor, the I
(connected
GAR
EE
GAR
CC
is
7
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
or open-circuit, the DTMF input is enabled and the
microphone and receiving amplifiers inputs are disabled.
When MUTE is HIGH, the microphone and receiving
amplifiers inputs are enabled while the DTMF input is
disabled.
DTMF amplifier (pin DTMF)
When the DTMF amplifier is enabled, dialling tones may
be sent on line. These tones can be heard in the earpiece
at a low level (confidence tone).
The TEA1113 has an asymmetrical DTMF input. The input
impedance between DTMF and V
gain from pin DTMF to pin LN is 25.4 dB. When the
resistor R
gain, the DTMF gain varies in the same way (the DTMF
gain is 26.4 dB lower than the microphone gain with no
AGC control).
The automatic gain control has no effect on the DTMF
amplifier.
Sidetone suppression
The TEA1113 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
R
k
Z
CC
bal
SLPE
=
// Z
---------------------------------------------------------------------- -
=
EE
R
k Z
line
. This resistor enables the I
ast2
R
GAS
, R
ast1
R
line
ast1
ast1
is connected, to decrease the microphone
R
=
, R
ast3
R
R
ast2
CC
SLPE
+
, R
R
SLPE
ast3
R
ast2
, R
SLPE
+
AGC
EE
R
start
ast3
is 20 k . The voltage
and Z
Product specification
between pins AGC
and I
TEA1113
bal
start
stop
(see Fig.10)
and I
line
bal
stop
.
is