Philips Semiconductors
Product specification
Low voltage versatile telephone
transmission circuit with dialler interface
PINNING
SYMBOL
LN
SLPE
REG
n.c.
DTMF
MUTE
IR
AGC
MIC−
MIC+
V
EE
QR
GAR
V
CC
PIN
1
2
3
4
5
6
7
8
9
10
11
12
13
14
DESCRIPTION
positive line terminal
slope (DC resistance) adjustment
line voltage regulator decoupling
not connected
dual-tone multi-frequency input
mute input to select speech or
dialling mode (active LOW)
receiving amplifier input
automatic gain control/
line loss compensation
inverting microphone amplifier input
non-inverting microphone amplifier
input
negative line terminal
receiving amplifier output
receive gain adjustment
supply voltage for speech circuit and
peripherals
handbook, halfpage
TEA1110A
LN
SLPE
REG
n.c.
DTMF
MUTE
IR
1
2
3
14 VCC
13 GAR
12 QR
4
TEA1110A(T)
11 VEE
5
6
7
MGG735
10 MIC+
9
MIC−
8 AGC
Fig.2 Pin configuration.
FUNCTIONAL DESCRIPTION
All data given in this chapter are typical values, except
when otherwise specified.
Supply (pins LN, SLPE, V
CC
and REG)
The supply for the TEA1110A and its peripherals is
obtained from the telephone line. See Fig.3.
The IC generates a stabilized reference voltage (V
ref
)
between pins LN and SLPE. V
ref
is temperature
compensated and can be adjusted by means of an
external resistor (R
VA
). V
ref
equals 3.35 V and can be
increased by connecting R
VA
between pins REG
and SLPE (see Fig.4), or decreased by connecting R
VA
between pins REG and LN. The voltage at pin REG is
used by the internal regulator to generate V
ref
and is
decoupled by C
REG
, which is connected to V
EE
. This
capacitor, converted into an equivalent inductance
(see Section “Set impedance”), realizes the set
impedance conversion from its DC value (R
SLPE
) to its AC
value (R
CC
in the audio-frequency range). The voltage at
pin SLPE is proportional to the line current.
The voltage at pin LN is:
V
LN
=
V
ref
+
R
SLPE
×
I
SLPE
I
SLPE
=
I
line
–
I
CC
–
I
P
–
I
∗
Where:
I
line
= line current
I
CC
= current consumption of the IC
I
P
= supply current for peripheral circuits
I* = current consumed between LN and V
EE
.
The preferred value for R
SLPE
is 20
Ω.
Changing R
SLPE
will
affect more than the DC characteristics; it also influences
the microphone and DTMF gains, the gain control
characteristics, the sidetone level and the maximum
output swing on the line.
1997 Apr 22
4
PHILIPS [ NXP SEMICONDUCTORS ]
