TEA1081 Philips Semiconductors, TEA1081 Datasheet - Page 5

• Manufacturer Part Number: TEA1081
• Description: Supply circuit with power-down for telephone set peripherals
• Manufacturer: Philips Semiconductors

Philips Semiconductors
Input and output currents I
The maximum available current into pin 1 (I
determined by:
That is I
At V
I
Where:
With large line signals the instantaneous line voltage may
drop below V
instantaneous current flows from LN to QS (pin 1 to pin 7)
to the output load.
When V
diverted to pin 2 to prevent distortion of the line signal.
September 1994
1
handbook, halfpage
The minimum line current (I
the telephone set
The specified minimum input current (I
speech/transmission circuit.
= I
I
k = correction factor (k < 1.1 for the specified output
current range).
Supply circuit with power-down for
telephone set peripherals
R
(1) I
(2) I
(3) I
INT
V
Fig.4 Output voltage as a function of line voltage.
LN(rms)
INT
connected between QS and VA.
V O
(V)
= internal supply current (0.8 mA at V
1
1
1
= 5 mA.
= 20 mA.
= 30 mA; not valid for TEA1081T.
1max
LN
+ k
6
4
2
0
0
< V
< 150 mV, the input current I
= I
O
I
O
O
+ 0.4 V. Normally (when V
LINEmin
+ 0.4 V, the instantaneous current is
(mA)
2
(2)
(1)
I
LNmin
4
(3)
1
LINEmin
.
and I
6
R = 100 k
O
V
) that is available for
(pins 1 and 7)
1
75 k
50 k
8
LN
LNmin
is approximately:
V
LN
> V
1
LN
MLC169
) is
(V)
) for the
= 4 V);
O
10
+ 0.4 V),
5
Input current at V
approximates to:
I
The maximum supply current (within the specified output
current limits) available for peripheral devices is shown by:
I
Where:
Input low-pass filter: IF (pin 5)
The input impedance between LN and VN at audio
frequencies is determined by the filter elements C
(between pins 1 and 5), R
internal resistor R
At audio frequencies the TEA1081 behaves as an inductor
of the value L
C
Amplifier decoupling: AD (pin 3)
To ensure stability, a 68 pF decoupling capacitor is
required between AD (pin 3) and LN (pin 1).
If I
between AD (pin 3) and VA (pin 6).
Power-down inputs: PD and SP (pins 4 and 8)
During pulse dialling or register recall, or if the input current
to pin 1 is insufficient to maintain the output current, the
supply to peripheral devices can be switched off by
activating the PD input at pin 4. With PD = HIGH, the input
current is reduced to 40 A (typ.) at V
internal circuits are isolated from the load at QS (pin 7).
The power-down circuit is supplied via the SP input (pin 8).
SP can be wired to QS in conditions where V
during line interruptions. When V
wired to an external supply point (e.g. to V
TEA1060 family circuit).
When power-down is not required, the PD and SP inputs
can be left open-circuit.
1
Omax
L
= I
I
I
speech/transmission circuit.
Omin
LINEmin
LNmin
= 2.2 F and R
INT
=
< 1.5 mA, a 47 pF capacitor has to be added
+ 2
I
---------------------------------------------------------- -
is the specified minimum input current of the
LINEmin
is the minimum line current of the telephone set;
I
I
= C
O
(mA)
–
LN(rms)
L
S
I
L
2
LNmin
(typical value 20 ).
= 100 k is 4.4 H.
R
L
= 1 V and without R
–
L
R
I
(between pins 5 and 7) and the
INT
S
(H). The typical value of L
O
< V
Product specification
LN
SPmin
= 4 V and the
TEA1081
CC
, SP should be
V
O
of the
> V
L
SPmin
I
at