MB86437 Datasheet, PDF (17/35 Pages) Fujitsu Component Limited. – 3 V Single Power Supply Audio Interface Unit (AIU)

MB86437
4. Reception Connections
This section describes reception connections, sidetone addition, and melody IC connection.
(1) Reception connections
This describes the connection to the speaker amp for the reception signal.
Provide a high-pass filter at AMP4 to prevent a DC offset being applied to the speaker amp.
• First-order high-pass filter
EV2
PTBO
C1
R1
TBI
R2
SGC
–
+
AMP4
TBO
To speaker amplifier
(2) Sidetone addition
Sidetone addition is implemented by connecting the STA output and AMP4. In this case, use of a resistor of
approximately 100 kΩ at AMP4 is recommended as the SW1 on resistance affects the sidetone gain.
sw1
STA
TBI
SGC
–
+
AMP4
TBO
To speaker amplifier
PTBO
C1
C1
R1
R2
R1: Use a resistor of approximately 100 kΩ.
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