ASAHI KASEI
[
[AK2358FI
D e s c r i p t i o n
I
The AK2358F, abase-band LSI for europian cordless telephone (CT1, CT1+), has built-in
voice filters, a 2400bps MSK MODEM for data communication, a frame detection circuit,
a COMPANDOR for noise reduction, and scrambler circuits.
The CMOS process provides low power operation. Application of 24 pin VSOP package with
the feature of significant reduction of external component provides minimum mounting area.
The time constant circuit for the COMPANDOR output transient response is built into the
LSI.
Using a 2400bps MSK MODEM for data communication has realized high data reliability and
high speed communication at the same time.
This LSI is suitable for cordless system telephones etc. which requires complicated
protocol control.
An oscillation circuit with a 3.58MHz crystal oscillator is built in, and no other
frequency source is required for the MSK MODEM. The oscillator also can be used for the
other DTMF generator etc.
The scrambler circuit uses the simple inversion
u
ethod with inversion of the voice
spectrum around the carrier frequency. Two inversion frequencies can be selected.
Built-in electronic volumes provided for transmission and reception part realize automatic
adjustment of the microphone sensitivity and the modulator/demodulator sensitivity by
external EEPROM and microprocessor.
The transmission part is composed of high-pass filter, compressor, pre-emphasis circuit.
scrambler, limiter, MSK modulator, splatter filter, electronic volume control, etc.
The reception part is composed of band pass filter, de-emphasis circuit, de-scrambler,
expander, buffer amplifier, MSK demodulator, frame detection circuit, electronic volume
control, etc.
s
Pin Arrangement
24pin VSOP
AGNDINC 1 0
TAGNDC 2
TXINC 3
TXINOC 4
LIMLVC 5
MODC 6
Vssc 7
TCLKC 8
TDATAC 9
D1/Oc 10
ROF/FDc 11
SCLK ~ 12
24 a RAGND
23 -J XXIN
22 -J RXINO
21 -J BUFOP
20 -J BUFON
19 -J RXAF
18 aBxAFIx
17 3 EXPOL’T
16 3 VDD
15 3 X1X
14 3 XOL’I
13 ~DIR
0152-E-00
-3-
199612
AKM [ ASAHI KASEI MICROSYSTEMS ]
