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TEA1112AT/C1 View Datasheet(PDF) - Philips Electronics

Part NameDescriptionManufacturer
TEA1112AT/C1 Low voltage versatile telephone transmission circuits with dialler interface Philips
Philips Electronics Philips
TEA1112AT/C1 Datasheet PDF : 20 Pages
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Philips Semiconductors
Low voltage versatile telephone
transmission circuits with dialler interface
Product specification
TEA1112; TEA1112A
FUNCTIONAL DESCRIPTION
All data given in this chapter are typical values, except
when otherwise specified.
Supply (pins LN, SLPE, VCC and REG)
The supply for the TEA1112; TEA1112A and their
peripherals is obtained from the telephone line.
The ICs generate a stabilized reference voltage (Vref)
between pins LN and SLPE. This reference voltage is
equal to 3.35 V, is temperature compensated and can be
adjusted by means of an external resistor (RVA). It can be
increased by connecting the RVA resistor between
pins REG and SLPE (see Fig.5), or decreased by
connecting the RVA resistor between pins REG and LN.
The voltage at pin REG is used by the internal regulator to
generate the stabilized reference voltage and is decoupled
by a capacitor (CREG) which is connected to VEE. This
capacitor, converted into an equivalent inductance (see
Section “Set impedance”), realizes the set impedance
conversion from its DC value (RSLPE) to its AC value (RCC
in the audio-frequency range). The voltage at pin SLPE is
proportional to the line current. Figure 4 illustrates the
supply configuration.
The ICs regulate the line voltage at pin LN, and can be
calculated as follows:
VLN = Vref + RSLPE × ISLPE
ISLPE
=
Iline ICC Ip I
=
ILED
+
I
sh
Where:
Iline = line current
ICC = current consumption of the IC
Ip = supply current for peripheral circuits
I* = current consumed between LN and VEE
ILED = supply current for the LED component
Ish = the excess line current shunted to SLPE (and VEE)
via LN.
The preferred value for RSLPE is 20 . Changing RSLPE will
affect more than the DC characteristics; it also influences
the microphone and DTMF gains, the LED supply current
characteristic, the gain control characteristics, the
sidetone level and the maximum output swing on the line.
The internal circuitry of the TEA1112; TEA1112A is
supplied from pin VCC. This voltage supply is derived from
the line voltage by means of a resistor (RCC) and must be
decoupled by a capacitor CVCC. It may also be used to
supply peripheral circuits such as dialling or control
circuits. The VCC voltage depends on the current
consumed by the IC and the peripheral circuits as shown
by the formula (see also Figs.6 and 7). RCCint is the
internal impedance of the voltage supply point, and Irec is
the current consumed by the output stage of the earpiece
amplifier.
VCC = VCC0 RCCint × (Ip Irec)
VCC0 = VLN RCC × ICC
Rline
handbook, full pagewidth
Iline
RCC
619
Rexch
Vexch
ILED
LN
TEA1112
TEA1112A
ILED
Ish
LED
DRIVER
Rp
15.5 k
from pre amp
RGASint
69 k
I*
Vd
Rd
SLPE
45.5 k
REG
ISLPE
RSLPE
20
CREG
4.7 µF
VCC
ICC
VEE
Fig.4 Supply configuration.
1997 Mar 26
5
IP
CVCC
100 µF
peripheral
circuits
MBE789
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