|TEA1098TV||Speech and handsfree IC|
|TEA1098TV Datasheet PDF : 40 Pages |
Speech and handsfree IC
All data given in this chapter are typical values, except
when otherwise specified.
LINE INTERFACE AND INTERNAL SUPPLY (PINS LN, SLPE,
REG AND VBB)
The supply for the TEA1098A and its peripherals is
obtained from the line. The IC generates a stabilized
reference voltage (Vref) between pins SLPE and GND.
This reference voltage is equal to 3.7 V for line currents
lower than 18 mA. It than increases linearly with the line
current and reaches the value of 6.1 V for line currents
higher than 45 mA. For line currents below 9 mA, the
internal reference voltage generating Vref is automatically
adjusted to a lower value. This is the so-called low voltage
area and the TEA1098A has limited performances in this
area (see Section “Low voltage behaviour”). This
reference voltage is temperature compensated.
The voltage between pins SLPE and REG is used by the
internal regulator to generate the stabilized reference
voltage and is decoupled by means of a capacitor between
pins LN and REG.
This capacitor converted into an equivalent inductance
realizes the set impedance conversion from its DC value
(RSLPE) to its AC value (done by an external impedance).
The IC regulates the line voltage at pin LN and can be
calculated as follows:
VLN = Vref + RSLPE × ISLPE
ISLPE = Iline – Ix
Iline = line current
Ix = current consumed on pin LN (approximately a few µA)
ISLPE = current flowing through the RSLPE resistor
The preferred value for RSLPE is 20 Ω. Changing this value
will affect more than the DC characteristics; it also
influences the transmit gains to the line, the gain control
characteristic, the sidetone level and the maximum output
swing on the line.
handbook, full pagewidLthN
Fig.3 Line interface principle.
2000 Aug 18
|Direct download click here|
|Share Link :|