pbl3853 ETC-unknow, pbl3853 Datasheet - Page 9

• Manufacturer Part Number: pbl3853
• Description: Universal Speech Circuit
• Manufacturer: ETC-unknow

V
V
V
Expression for DC-characteristics. from figure16, (empirical).
If the resistors R
will have somewhat more complex expression:
If the resistors R
NOTE
Figure 14.
Figure 15.
I
Z
L
1
F
X
X
V
5.8 V
R
1. These expressions are
2. These expressions are built
V
L
1
V
V
A
F
TO
R
F
built on the asumption that the
and that the influence of
capacitors except C
neglected.
on an ideal situation and are
only for help to understand
5
R
of the transistors is infinite
R
R
a
2.0 / 45 0.14
b
5
V
5
T
1
X
2.0 / 45 10
x
B
2
V+L
L
0.18
R
Z bal
C
0.18 10
R
6
6
1
A
A
6
PBL 3853
1.3 V
2.5 10
R
R
and R
and R
8
0.65
9
C
I
R
1
L
Z
7
R
R
bal
R
10
11
7
B
R
R
DC
B
3
15
3
are set to infinity in this expression it will take the same form as above.
are connected in the circuit as in figure 16, the V
12
13
3
R
RI
2
R
R
10
0.07 10
1/ 2.5 10
x
11
can be
0.14 10
16
.......................................................................................................................................9
Telephone
set side
Z in
0.65
R
13
3
...........................................................................................................................10
Z
3
3
2
R
0.6 10
19
Z 2.5 10
Line side
Z V
Z
Z
1
Line
L
3
/ 2.5 10
R
3 2
1
R
2
3
Figure 16.
MUTE and Cut-off Function
The receiver mute (pin 17) is a cut-off function. The normal
receiver amplifier is cut-off but a second amplifier is activated
to let the DTMF or the payphone signal injected to pin 17 get
through to the earphone. The input level for cut-off:
V cut-off = Rx output (VDC/2) + 2x V diode
3.5 V
be injected to pin 17 at correct DC level or via a capacitor.
with at diode. The diode is needed in order not to disturb the
DC-level at pin 17 in not muted condition.
(pin 18) with a series resistor (see figure 10).
R
The signal for DTMF confidence tone in the earphone must
The mute signal is taken from pin 18 via a resistor in series
The transmit mute (pin 10) can be taken from the same point
A
....................................................................................8
V
................................................................................11
Active impedance
X
section
+
-
R12
R5
I
V
1
+
-
R13
Telephone
Passive impedance
2.2 V + 1.3 V
section
I
Z
Load
p
PBL 3853
Z
Line
Line
I
L
V
L
9