FEDL7732-01-10

OKI Semiconductor

MSM7732-01

6/29

PIN FUNCTIONAL DESCRIPTION

AIN+, AIN–, GSX

Transmit analog inputs and the output for transmit gain adjustment.

AIN– connects to inverting input of the internal transmit amplifier. AIN+ connects to non-inverting input of the

internal transmit amplifier. GSX connects to the internal transmit amplifier output. Refer to Figure 1 for gain

adjustment.

VFRO, SAO, AOUT+, AOUT–, PWI

Receive analog outputs and the outputs for receive gain adjustment.

VFRO is the receive filter output for the voice signal. SAO is the receive filter output for an acoustic component of

the sound tone. SAO can directly drive 32

Ω load. AOUT+ and AOUT– are differential analog signal outputs

which can directly drive a 32

Ω load. Refer to Figure 1.

Figure 1 Analog Input/Output Interface

AIN–

R2

R1

C1

Vi

+

–

10 µF

Transmit Gain:

+

–

AIN+

GSX

SG

VREF

to ENCODER

SAO

VFRO

D/A

Conv.

–1

AOUT+

AOUT–

PWI

R3

R4

Sounder output signal

×2

0.1 µF