pbl385822sot ETC-unknow, pbl385822sot Datasheet - Page 8

• Manufacturer Part Number: pbl385822sot
• Description: Telephone Line Interface Circuit Dect Unisolated Isolated
• Manufacturer: ETC-unknow

Note that the signals at points a. and b. are
180 degrees off phase.
10 x R6
R7
The ac-signal at point c. is now 1/10 of the
signal on the line because it is further
divided by two from point b. (R7 Zbal).
Hence 10 x R1 R2 to satisfy the balancing
criteria. R12 is to set the receiver gain. (
can also be a volume control potentio-
meter).
frequency behaviour of the transmitter is
not influenced. With the ratio 1/10 the
influence is 1 dB, and with ratio 1/20 it´s 0.5
dB.
compared with Zbal, it will load the latter
and
perfomannce, again if the R7 is made high
ohmic compared with Zbal will result in a
Figure 12. Typical insulated DECT-set line interface. DIP package.
PBL 385 82
Note #1 These values ensure that the
Note #2
8
RECEIVE
TRANSMIT
Zbal
result in a bad side tone
R7 + Zbal
If the R7 is made low ohmic
1m F
C7
3
C3
0.1m F
Note#2
2
2
Note #1
1 7
1 8
PBL 38582
6
10k
R14
Limiter
C6
low signal to balance the side tone with and
make the balancing difficult. Making any of
the impedances unnecessary high will
make the circuit sensitive to RFI. All values
given here are approximate and serve as
starting entities only. The
of side tone network is a cut and try propo-
sition because a part of the balance lies
in the acoustical path between the
microphone and earphone.
3
Start up circuit
which function is to fast charge capacitor
C1 when the circuit goes into hook- off
condition. The fast charge circuit is a
thyristor function between pins 1 and 4 that
will stop conducting when the current
drainat pin 4 is lower than
The circuit contains a start up device
1
2
>0.5W
75W
R1 6.2k
R6
C4
1 5
Reference
Fast start - up
47nF
R2 62k
5,
14,16
700 A + the
final trimming
supply
DC
+
4
68 m F
910 W
C1
R3
Figure 11. Fast startup function.
internal current consumption ( about 1
mA). Care must be taken when connecting
external load to pin 4 in order not to exeed
the
would result in an inoperative speech
funktion. This circuit can not retrigger before
the voltage level at C1 drops below 2V or
the line voltage is below 1V. See fig. 10.
700 A limit. Should this happen, it
R6
Tx
1
2
C2 15nF
1
PBL 38 5 82
D3
D1
DC supply
4
D5
D2
D4
R3
C1
Telephone
line
+Line
-Line