PBL 3726/18A
placed between pin 17 (19) and 18 (20).
See figure17.
value by applying one or two resistor
(RDC1, RDC2) in parallel with the
internal resistors (each 15 kΩ + /-20 %).
It is possible to get a rather high voltage
and current from the DC-supply as long
as the high current and voltage is
Design procedure:
1. Circuit impedance to the line.
2. DC-characteristic.
3. Gain regulation.
4. Transmitter gain and frequency
response.
5. Receiver gain and frequency
response.
R15
This resistor is used to set the driving
capability of the receiver output amplifier.
Common values are 0 ohm to 50 ohm.
Setting it for low driving capability results
in function at lower line current. Breaking
up pin 16 (18) will give lower power
consumption and total mute of the
available from the line. The DC voltage
has to be filtered by a capacitor and this
can, at high DC-voltage and low line
current, interfere with the signal on the
line and course distortion. The interfer-
ence can be minimized, with a resistor in
series with the filter capacitor. The DC
voltage will, of course, be more depen-
dent of the DC-supply current. The DC-
output pin has a very low input leak
current, to allow stand-by feeding of the
dialler. It is also possible to use pin 9 to
feed microphones etc. that do not need
stand-by feeding, without interfering with
the stand-by feeding on pin 8. Note that a
high current consumption by the external
device will alter the DC characteristics of
the speech circuit.
6. Side-tone.
7. Components to suppress radio
interference, specially the wires
up to the handset.
receiver when muting the circuit.
Others:
D1, D2, D3, D4, D5
The circuit can be placed either in the
telephone or in the handset.
Cut-off of the transmitter can be done
at F1 without interference of other
functions of the circuit.
When using the extended low current
and low voltage range (5 mA, 2 V), two
resistors have to be connected from the
microphone inputs to ground as shown in
figure 14.
Rectifier bridge and overvoltage protec-
tor. The zener voltage at D5 should be
as low as possible. Common values are
between 12 V - 16 V.
RDC1, RDC2
Refer to figure 7.
The preset output voltage of 2.35 V can
easily, if needed, be changed to another
Ordering Information
Package
Temp. Range
Part No.
Plastic DIP
Plastic SO
Plastic SO
-40 to +70°C
-40 to +70°C
-40 to +70°C
PBL 3726/18AN
PBL 3726/18ASO
PBL 3726/18ASO-T
Information given in this data sheet is believed to be
accurate and reliable. However no responsibility is
assumed for the consequences of its use nor for any
infringement of patents or other rights of third parties
which may result from its use. No license is granted
by implication or otherwise under any patent or patent
rights of Ericsson Components. These products are
sold only according to Ericsson Components' general
conditions of sale, unless otherwise confirmed in
writing.
Specifications subject to change without
notice.
IC4 (88087) B-Ue
© Ericsson Components AB 1996
Ordering number: PZA 2510
Ericsson Components AB
S-164 81 Kista-Stockholm, Sweden
Telephone: (08) 757 50 00
8
ERICSSON [ ERICSSON ]
