Preliminary AS2525
Rev. 1.3 Page 1 May 1999
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
Block Diagramme
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.
CS
SS
LI
VPP
LS
+ –
+
–
+
–
+
VSS
30 Ω
RI
STB
300 Ω
ZBAL
AGND
VDD
VDD
VDD
–
+
VPP
VPP
M1
M2
M3
M4
LO1
LO2
VSSA
RECI
RECV
RO
NOISE
DET.
LINE
SENSE
PEAK
DET.
VOICE
SWITCHING
PEAK
DET.
DTMF
MELODYDEBOUNCE
CPU
DIALLER DC/DC
CONVERTEROSCILLATORKEYSCANNING
CMKEYBOARD (C1-4/R1-3)
HS
HF
DM/HM
FCI
DPN
LED
DI DO CLK CS1 CS2
VSS
CI
SUPPLY VREF
VDD
AGND
AGND
FT2 CBN FT1
AS2525
3.58
MHz
Austria Mikro Systeme International AG
Single-Chip Handsfree Phone
CMOS Integrated Circuit