tea1085t NXP Semiconductors, tea1085t Datasheet - Page 7

• Manufacturer Part Number: tea1085t
• Description: Listening-in Circuit For Line-powered Telephone Sets
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Supply; SUP, SREF, V
The line current is divided into I
The supply arrangement is illustrated in Fig.4.
Where:
A practical value for R20 is 150 . This value of resistance
produces a value for I
The TEA1085/TEA1085A stabilizes its own supply voltage
at V
internal circuits. TR2 is used to minimize the signal
distortion on the line by momentarily diverting the input
current to V
voltage V
fixed to a typical value of 3.6 V but can be increased by
means of an external resistor (R38) connected between
March 1992
handbook, full pagewidth
V
R20
I
CC
int
Listening-in circuit for line-powered
telephone sets
I
TR
BB
is constant: I
. Transistor TR1 provides the supplies for the
SUP
is an internal temperature compensated
reference voltage with a typical value of
315 mV between SUP and SREF
is a resistor between SUP and SREF
is the internal current consumption of the
TEA106X ( 1 mA)
SS
LINE
drops below the supply voltage V
whenever the instantaneous value of the
TR
= V
I line
int
TR
I CC
/ R20; I
BB
= 2 mA and I
, V
V CC
V EE
SUP
SS
TEA1060
R1
= I
and VA
TR
line
I TR
for the TEA1060 and I
SLPE
I
LN
CC
SUP
R20
R9
I
I SUP
TR
= I
line
Fig.4 Supply arrangement.
BB
SUP
SREF
. V
3 mA.
TEA1085A
TEA1085
BB
is
V int
SUP
7
for the TEA1085/TEA1085A.
VA and V
between VA and V
restricted to 3.0 V; the level of the V
affected (see application report for further information).
The supply at V
The DC voltage (V
transmission IC (V
V
The minimum DC voltage that can be applied to this input
is V
Where: V
depends on the setting of R38, which is connected
between VA and V
The internal current consumption of the
TEA1085/TEA1085A (I
V
for powering the loudspeaker is I
The current I
the circuitry connected to SUP and current I
which is used for the circuitry connected to V
SUP
SUP
BB(max)
I BIAS
TR1
V
V
SS
SS
BB(max)
SS
TR2
= 4.5 V, MUTE off). Thus the current available
= V
or decreased by connecting this resistor
SUP0
0.4 V.
LN SLPE
BB
is the worst case supply voltage (this
consists of a bias current of 0.4 mA for
V SS
LN SLPE
is decoupled by a 470 F capacitor.
SUP
BB
SS
STABILIZER
VOLTAGE
. The minimum level on V
).
TEA1085; TEA1085A
SUP0
V
V
SS
); thus:
I BBO
int
) is typically 4.2 mA (where
) is determined by the
.
VA
R38
SUP
V BB
Preliminary specification
BB
MGR034
I
limiter is also
SUP0
BB0
C20
BB
.
of 3.8 mA
(see Fig.4).
BB
is