PBL 385 71
June 1999
PBL 385 71
High current Speech and
Line interface Circuit
Description.
PBL 38571 is a monolithic integrated speech transmission circuit for use in
electronic telephones and as DECT line interface with balanced in - and output. It is
designed to accomodate either a low impedance dynamic microphone or an electret
microphone that can be supplied from the circuits own DC - supply. A signal summing
point at the transmitter input is available. An internally preset line length
compensation can be adjusted with external resistors to fit into different current feed
systems as for ex. 48 V, 2 x 200 ohms, 48 V, 2 x 400 ohms and 48 V, 2 x 800
ohms.The line regulation can be shut off in low mode. Application dependent para-
meters such as line balance, side tone level, transmitter and receiver gains and
frequency responces are set independently by external components which means an
easy adaption to various market needs. The setting of the parameters, if carried out in
certain order will counteract the interaction between the settings. It features high line
current capability on a small footprint. Function compatible with the PBL 3781 family
of speech circuits.
Key features.
•
Minimum number of external
components, 5 capacitors and 10
resistors.
Easy adaption to various market
needs.
Mute control input for operation with
DTMF - generator.
Transmitter and receiver gain
regulation for automatic loop loss
compensation. Disconnectable.
Extended current and voltage range
5 - 130 mA, down to 2 V.
Differential microphone input for
good balance to ground.
Balanced receiver output stage.
In 16 - pin DIP and SO BW batwing
packages.
Short start up time.
Excellent RFI performance.
•
•
•
•
•
•
•
•
•
1
15
10
AM
11
AT
PBL 385 71
AR
REC
4,5,
12,13.
8
7
9
3
2
14
+6
16
Mute
(active low)
4
3
2
+
16-pin plastic BW SO
1
P
B
L
38
Telephone
line
1. Impedance to the line and radio interference suppression
2. Transmitter gain and frequency responce network
3. Receiver gain and frequency responce network
4. Sidetone balance network
Figure 1. Functional diagram.
1
P
16-pin plastic BW DIP
B
L
38
57
1
57
1
ERICSSON [ ERICSSON ]
