ASAHI KASEI
Block
AMP3
[AK2358FI
Function
The operational amplifier used on the smoothing filter of the
reception SCF output. Set the gain to OdB and the cut-off
frequency to about 20kHz by external resister and capacitor.
The SCF circuit to eliminate the low frequency component lower
than 100Hz from the reception MSK signal.
The circuit to reproduce the 2400bps receiving data and the clock
from the received MSK signal in the RXIN pin.
The inverting and the non-inverting buffer amplifier to drive the
ceramic receiver.
The circuit to generate the reference voltage for the internal
analog signal.
The circuit to oscillate the 3.58 MHz reference clock using an
external crystal oscillator and resistor.
The volume to control the input amplitude of the transmission
voice signal. The adjustment range is -8dB to +7dB by ldB step.
The volume to control the MOD output amplitude. The adjustment
range is -4dB to +3.5dB by 0.5dB step.
The volume to control the input amplitude of the reception
demodulation signal. “The adjustment range is -4dB to t3.5dB by
0.5dB step.
The volume to control the receiving voice amplitude. The
adjustment range is -12dB to +9dB by 3dB step.
The control register contlols the status of internal switches and
internal volumes of the LSI by serial data consists of 2 address
bits and 8 data bits. At the start up a power-on-reset circuit
works and the default values are set to the control register.
(see control register map.)
The data buffer stores 8 bits of the MSK receiving data to smooth
the signal interface with CPU.
P i n / F u n c t i o n
I
MSKHPF
MSK demodulator
AMP4
A!!P5
AGND
Oscillation
circuit
VR1
VR2
VR3
VR4
Control register
and data buffer
I
Pin No.
1
Pin name
AGNDIN
1 / 0
I
2
TAGND
o
3
TXIN
1
4
5
TXINO
LIMLV
o
1
I
\
Function
Analog ground input pin.
Connect the capacitor to stabilize the analog
ground.
Analog ground pin for the transmission system.
Connect the capacitor to stabilize the analog
ground.
-
Transmission voice input pin.
This is the inverting input pin for AMP1. It
composes a microphone amplifier with a external
resister and a caDacitor.
AilPl output pin.
Limitation level adjustment pin.
I The limitation level can be adjusted by applying a
\ DC voltage to this pin. The default limitation level
is adopted if no voltage is applied.
0152-E-00
5-
199612
AKM [ ASAHI KASEI MICROSYSTEMS ]
