Preliminary
AS2525
Single-Chip Handsfree Phone
CMOS Integrated Circuit
Austria Mikro Systeme International AG
Key Features
q
Line/speech handsfree circuit, LD/MF repertory
dialler, and tone ringer on one 44 pin CMOS chip
q
Operating range from 15 to 100 mA line current
(down to 5 mA with slightly reduced performance)
q
All significant parameters programmable with
external EEPROM
q
Volume control of receiver signal
q
Handsfree function with enhanced voice switching
q
Low noise (max. -72 dBmp)
q
Unique EMC performance
q
LD/MF switchable dialling with temporary MF
mode
q
Repertory dialling with last number redial and
memory dialling (8 x 2 direct and 10 indirect)
q
Call restriction with PIN code
q
Serial interface for EEPROM and LCD driver
q
2-tone/3-tone ringer with ring frequency detection
General Description
The AS2525 is a CMOS mixed-mode integrated
circuit for use in feature phones, answering machines
and fax machines. It contains an analogue line
interface and speech circuit for a/b terminals,
loudhearing, handsfree, enhanced LD/MF dialler, tone
ringer with dc/dc converter and serial interface to
EEPROM and LCD-driver (AS2591), all in a 44 pin
package. The circuit is fully line powered.
The AS2525 uses an external EEPROM for a 31 digit
last number redial storage and memories for 26
numbers each containing up to 21 digits/data.
The device provides a volume control for the earpiece
and the loudspeaker. The volume can be controlled by
pressing the
[V-]/[V+]
keys.
The versatility of the circuit is provided by
programming all parameters through an external
EEPROM. This allows easy adaptation to various PTT
requirements worldwide.
Package
Available in 44 pin TQFP.
Block Diagramme
LS
V
DD
V
DD
LINE
SENSE
SUPPLY
V
REF
FT2
A
GND
A
GND
NOISE
DET.
+
CS
–
SS
+
+
A
GND
–
M3
PEAK
DET.
M4
V
PP
V
SS
CI
300
Ω
RI
STB
+
Z
BAL
–
PEAK
DET.
LO2
V
SSA
RECI
HS
HF
DM/HM
DEBOUNCE
DTMF
MELODY
RECV
V
SS
–
+
VOICE
SWITCHING
V
PP
LO1
M2
CBN
FT1
M1
V
DD
30
Ω
LI
AS2525
V
DD
V
PP
RO
FCI
DPN
LED
CPU
DIALLER
DC/DC
CONVERTER
KEYSCANNING
OSCILLATOR
DI DO CLK
CS1 CS2
KEYBOARD (C1-4/R1-3)
3.58
MHz
CM
Rev. 1.3
Page 1
May 1999
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
