U4083 TEMIC Semiconductors, U4083 Datasheet - Page 2

• Manufacturer Part Number: U4083
• Description: Low-Power Audio Amplifier for Telephone Applications
• Manufacturer: TEMIC Semiconductors

Pin Description
Functional Description
Including External Circuitry
Pin 1: Chip disable
Pin 1 (chip disable) is used to power down the IC to con-
serve power or muting or both.
Input impedance at pin 1 is typically 90 k
Figure 15 shows power supply current diagram. The
change in differential gain from normal operation to
muted operation (muting) is more than 70 dB.
Switching characteristics are as follows:
They are independent of C
Voltages at Pins 2 and 3 are supplied from V
fore do not change when the U4083B is disabled.
Outputs– V
pedance condition by removing the signal from the
speaker.
When signals are applied from an external source to the
outputs (disabled), they must not exceed the range be-
tween the supply voltage, V
Pins 2 and 3: Filtering, power supply rejection
Power supply rejection is provided by capacitors C
C
frequencies whereas C
(figures 4 to 7). Values of C
conditions of each application. For example, a line
powered speakerphone (telephone amplifier) will require
more filtering than a system powered by regulated power
supply.
The amount of rejection is a function of the capacitors and
the equivalent impedance looking into Pin 3 and Pin 2
U4083B
2 (11)
Logic 0 < 0.8 V
Logic 1 > 2 V
2
at Pin 3 and Pin 2, respectively. C
turn-on time
turn-off time
CD
FC2
FC1
V i
O1
(Pin 5) and V
1
2
3
4
Figure 2. Pinning
*
IC enabled (normal operation)
IC disabled
2
digital input (CD)
is dominant at low frequencies
1
, C
s
O2
t
t
, and Ground.
on
off
2
(Pin 8) –turn to a high im-
1
= 12 to 15 ms
v
and V
and C
2
1
m
Preliminary Information
8
7
6
5
S
is dominant at high
s
.
2
W
depend on the
VO2
GND
V S
VO1
.
S
and there-
94 8022
1
and
(see electrical characteristic equivalent resistance, R).
Apart from filtering, capacitors C
the turn-on time of the circuit at power-up since capaci-
tors are charged up through the internal resistors (50 k
and 125 k
Figure 1 shows turn-on time versus C
different C
Turn-on time is 60% longer when V
shorter when V
Turn-off time is less than 10
Pin 4: Amplifier input
Pin 5: Amplifier output 1 V
Pin 8: Amplifier output 2 V
There are two identical operational amplifiers. Amp.1 has
an open loop gain
the closed loop gain is set by external resistors, Rf and Ri
(figure 3). The amplifier is unity gain stable, and has a
unity gain frequency of approximately 1.5 MHz. A closed
loop gain of 46 dB is recommended for a frequency range
of 300 to 3400 Hz (voice band). Amp.2 is internally set
to a gain of –1.0 (0 dB). The outputs of both amplifiers are
capable of sourcing and sinking a peak current of 200 mA.
Output voltage swing is between 0.4 V and V
maximum current (figures 18 and 19).
The output dc offset voltage between Pins 5 and 8 (V
– V
because the input offset voltage of the two amplifiers
generally neutralize each other.
Bias current of Amp. 1 which is constant with respect to
V
forcing V
and V
The output offset voltage specified in the electrical char-
acteristics is measured with the feedback resistor
(R
into account bias current as well as internal offset voltages
of the amplifiers.
s
Pin
, however flows out of Pin 4 (V
f
1
2
3
4
5
6
7
8
O2
= 75 k
O2
) is mainly a function of the feedback resistor, R
positive to an equal amount.
01
W
W
Symbol
1
) as shown in the block diagram.
GND
) shown in typical application circuit. It takes
VO1
VO2
to shift negative by an amount equal to R
values.
FC2
FC1
CD
V
V
S
i
S
= 9 V.
w
80 dB at 100 Hz (figure 2), whereas
Chip disable
Filtering, power supply rejection
Filtering, power supply rejection
Amplifier input
Amplifier output 1
Voltage supply
Ground
Amplifier output 2
TELEFUNKEN Semiconductors
V
m
i
O1
O2
s
1
Function
and C
2
Rev. A2, 07-Apr-97
i
at V
S
) and through R
= 3 V and 20%
2
S
also influence
= 6 V, for two
s
– 1.3 V at
f
I
O1
IB
W
f
f
,
,