U4030B TEMIC Semiconductors, U4030B Datasheet - Page 3

• Manufacturer Part Number: U4030B
• Description: Telephone Speech Circuit
• Manufacturer: TEMIC Semiconductors

Rev. A2, 27-Jan-98
Circuit Description
Reference for all descriptions is figure 9, unless otherwise
specified.
Power Supply
DC characteristic
The power supply stage determines the voltage/ current
characteristic of the circuit. The DC-slope is adjusted to
100
used to reduce the line voltage ( figure 2 ).
V
IRDC
with:
I
VRS
R30
IDC
V
An unregulated voltage, V
internal and external circuits. The maximum voltage at
this pin is limited by an internal Z-diode to a value of
6.2 V. The available output current is shown in figure 3.
V
The supply voltage for an electret microphone is derived
from V
OFFSET
L
D
M
93 7619 e
= ( 0.0033
W.
D
A resistor connected from Pin 2 to Pin 14 may be
16
12
RDC
8
4
0
(see figure 4). The output resistance is set to
0
= 150
= 150 mV
= 30 k
= I
Figure 2. DC characteristics
I
DC
L
20
- ( 750
m
W
+ I
RC =
A
OFFSET
RDC = 10 k
40
m
D
I
A + 0.023
L
, is generated to supply the
( mA )
)
RC = 100 k
60
W
( R30 || RC) + VRS+
80
I
W
L
)
100
300
V
Swamp
Line current which is not used for internal and external
circuits is converted into heat via resistance Rswamp in
order to prevent the IC from thermal destruction at high
line currents.
The speech circuit will be high ohmic when the voltage
at SWAMP reaches 6 V. Typical characteristics for
various resistors are shown in figure 5.
M
93 7620 e
93 7621 e
-pin is virtual ground for the receiving amplifier.
W
and the maximum output current is 300
Figure 4. Electret microphone supply, V
6
4
2
0
2
1
0
3
0
Figure 3. Supply voltage, V
V (MIC) = 10 mV
4
Supply voltage V
Supply current I
4
8
19 mA
I
eff
L
= 50 mA
12
D
D
U4030B
( mA )
5
( mA )
D
24 mA
16
M
m
20
6
A. The
3 (14)