L6726
LINEAR INTEGRATED CIRCUIT
APPLICATION INFORMATION(Cont.)
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.
6. Side-tone.
7. Components to suppress radio interference, specially the wires up to the handset.
Others:
The circuit can be placed either in the telephone or in the handset.
Cut off 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 (5mA, 2V), two resistors have to be connected from the
microphone inputs to ground as shown in fig. 13.
11
3
11
3
2
15
+Line
RA
R11
R10
CA
RA
RA
RB
CA
CB
R6
R6
R6
RB
11
3
11
3
2
15
RA
RB
RA
+Line
R10
RA
RB
R11
CA
CA
CB
RB
CB
CA
RC
11
3
3
11
3
3
CA
RA
RA
RB
2
15
CA
CA
+Line
R10
RA
R11
CB
RB
11
RB
RC
11
CA
RA
RA
RB
CA
CA
Fig. 8 Examples of network "4"
RB
CB
CB
Fig. 7 Examples of network "2"
UNISONIC TECHNOLOGIES CO., LTD
11 of 13
QW-R108-015, C
www.unisonic.com.tw
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