msm7542 Oki Semiconductor, msm7542 Datasheet - Page 4

• Manufacturer Part Number: msm7542
• Description: Single Rail Codec
• Manufacturer: Oki Semiconductor

¡ Semiconductor
PIN AND FUNCTIONAL DESCRIPTIONS
AIN+, AIN–, GSX
Transmit analog input and transmit level adjustment.
AIN+ is a non-inverting input to the op-amp; AIN– is an inverting input to the op-amp; GSX is
connected to the output of the op-amp and is used to adjust the level, as shown below.
When not using AIN– and AIN+, connect AIN– to GSX and AIN+ to SG. During power saving
and power down modes, the GSX output is at AG voltage.
AG
Analog signal ground.
VFRO
Receive filter output.
The output signal has an amplitude of 2.0 V
when the digital signal of +3 dBmO is input to PCMIN and can drive a load of 20 kW or more.
For driving a load of 20 kW or less, the output signal of AOUT+ and AOUT– is available.
To apply the output signal of AOUT+ and AOUT– for driving, connect a resistor of 20 kW or more
between the pins VFRO and PWI.
When adding the frequency characteristics to the receive signal, refer to the application example.
During power saving or power down mode, the output of VFRO is at the voltage level of AG.
1) Inverting input type
2) Non inverting input type
Analog input
Analog input
R5
C1
C2
R1
R3
R4
R2
GSX
AIN–
AIN+
SG
AIN+
AIN–
GSX
SG
PP
above and below the signal ground voltage (SG)
–
+
+
–
R1 : variable
R2 > 20 kW
C1 > 1/(2 ¥ 3.14 ¥ 30 ¥ R1)
Gain = R2/R1 £ 10
R3 > 20 kW
R4 > 20 kW
R5 > 50 kW
C2 > 1/ (2 ¥ 3.14 ¥ 30 ¥ R5)
Gain = 1 + R4 / R3 £ 10
MSM7541/7542
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