¡ Semiconductor

MSM7541/7542

4/20

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.

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.

–

+

AIN–

AIN+

C1

Analog input

1) Inverting input type

R1 : variable

R2 > 20 kW

C1 > 1/(2 ¥ 3.14 ¥ 30 ¥ R1)

Gain = R2/R1 £ 10

R2

GSX

SG

+

–

AIN+

AIN–

2) Non inverting input type

R3 > 20 kW

R4 > 20 kW

R5 > 50 kW

C2 > 1/ (2 ¥ 3.14 ¥ 30 ¥ R5)

Gain = 1 + R4 / R3 £ 10

R4

GSX

SG

C2

Analog input

R3

R5

R1