TEA1065 View Datasheet(PDF) - Philips Electronics
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TEA1065 Datasheet PDF : 28 Pages
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Philips Semiconductors
Versatile telephone transmission circuit with
dialler interface
Product specification
TEA1065
The DC current flowing into the set is determined by the
exchange supply voltage (Vexch), the DC resistance of the
subscriber line (Rline) and the DC voltage on the subscriber
set (see Fig.4).
If the line current exceeds ICC + 0.3 mA, required by the
circuit itself (ICC ≈ 1.14 mA), plus the current Ip required by
the peripheral circuits connected to VCC then the voltage
regulator will divert the excess current via LN.
VLN = Vref + ISLPE × R9 =
Vref + (Iline − ICC − 0.3 × 10−3 − Ip) × R9
where: Vref is an internally generated temperature
compensated reference voltage of 4.18 V and R9 is an
external resistor connected between SLPE and VEE.
The preferred value of R9 is 20 Ω. Changing R9 will
influence the microphone gain, gain control
characteristics, sidetone and the maximum output swing
on LN. In this instance, the voltage on the line (excluding
the diode rectifier bridge; see Fig.4) is:
Vline = VLN + VGS + R16 × IDOC
where: VGS is the voltage drop between the gate and
source terminal of the external line current control
transistor and IDOC is the current sunk by pin DOC
(IDOC = 0 in the voltage regulator mode and increases with
Iline in the current regulator mode).
Under normal conditions ISLPE >> ICC + 0.3 mA + Ip and
for the voltage regulator mode (Iline < Iknee), the static
behaviour of the circuit is equal to a 4.18 V voltage
regulator diode with an internal resistance of R9 in series
with the VGSon of the external line current control
transistor. For the current regulator mode (Iline > Iknee), the
static behaviour of the circuit is equal to a 4.18 V voltage
regulator diode with an internal resistance of R9 in series
with the VGSon of the external line current control transistor
and also in series with a DC voltage source R16
× IDOC (the preferred value of R16 is 1 MΩ at this value the
current IDOC is negligible compared to Iline).
In the audio frequency range the dynamic impedance
between LN and VEE is equal to R1 (see Fig.8). The
internal reference voltage Vref can be adjusted by means
of an external resistor RVA. This resistor, connected
between LN and REG, will decrease the internal reference
voltage. When RVA is connected between REG and SLPE
the internal reference voltage will increase.
The maximum allowed line current is given in Figs 5 and 6,
where the current is shown as a function of the required
reference voltage, ambient temperature and applied
package.
handbook, full pagewidth
Rline Vline Iline
R1
Rexch
Vexch
IDOC
R16
DOC
12
TEA1065
DC
AC
ISLPE
+ 0.5 mA
LN
1
ICC
VCC
Ip
21
0.3 mA
C1
peripheral
circuits
22
REG
C3
9
STAB
R5
24
SLPE
R9
16
VEE
MBA550
March 1994
Fig.4 Supply arrangement.
6
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