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The technical content of this austriamicrosystems datasheet is still valid.
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austriamicrosystems
Telephone Line Interface and
Speakerphone Circuit
AS2522B
Key Features
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DATA SHEET
General Description
AS2522 is a CMOS integrated circuit that incorporates DC
and AC line adaptation (DC-mask and synthesized AC-
impedance of 1000Ω) as well as a speech circuit with
e
softclipping, line loss compensation and Rx-volume control
ct s
for handset and handsfree operation. It shall act as an a/b-
U
line powered device, which is controlled by a CPU via a
2
rporates
serial interface. Furthermore the AS2522 incorporates a
nger ton
DTMF, FSK transmitter, single tone and ringer tone
generator.
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Applications
plications
cations
Pack
Package
A
Available in 32-pin TQFP
Line/Speech circuit, DTMF dialer, FSK transmitter and
tone ringer on a 32-pin CMOS-IC
Enhanced voice switching
Background noise monitoring
DTMF tone generator
FSK Transmitter V.23, BELL202, V.21, BELL 103
Ringer tone programmable
Tx- and Rx-gain programmable
Digital volume control of Rx signals
DC characteristic programmable
Dual softclipping in handset mode
Tx-softclipping in handsfree mode
Common monitor amplifier for loudhearing, handsfree
and ringing
Supply voltage generation for external circuitry
Automatic line loss compensation (LLC)
Real and complex impedance selectable by external
rnal
components
Side tone adaptation selectable by external components
al componen
Unique EMC performance
Operating range from 15mA to 100mA (down to 5mA
mA
5
with reduced performance)
Few external components
AS2
ff-the-shelf microprocessor
AS2522 allows to use an off-the-shelf micro
withou
without special blocks and functions for telephone
application
pplicati
F, SK transmitter
applications. DTMF, FSK transmitter, single tone and ringer
ge
controlled
tone gen
generator can be controlle via the serial interface as
a
ain set
in se
s ha
well as the gain settings in handset and handsfree mode.
Enhanced hands
anced handsf
handsfree feature phones with CallerID and
dis
disp
extended displays.
Block Diagram
Revision 3.4
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Data Sheet AS2522B
austriamicrosystems
Pin description
Pin #
13
Symbol
LS
Function
L
ine Current
S
ense Input
Analog input for sensing the line current
10
LI
L
ine
I
nput
Analog input used for power extraction and line current sensing
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11
RI
R
eceive
I
nput
Analog input for ac-separated receive signal
7
STB
S
ide
T
one
B
alance Input
Analog input for side tone cancellation network
8
CS
C
urrent
S
hunt Control Output
xtern
ransistor
N-channel open drain output to control the external high power shunt transistor for
synthesizing AC- and DC-impedance, modulation of line voltage and shorting the line during
dulation o
nd horting
lin
make periods of pulse dialing
14
CI
C
omplex
I
mpedance Input
or o
ex pedance
Analog input pin for the capacitor to program a complex impedance
12
SS
S
upply
S
ource Control Output
utput
N-channel open drain output to control the external high pow source transistor for supplying
power
cont
co
nal
(Vpp) the loudspeaker amplifier iin off-hook loudspeaking/handsfree mode
ker
ook loudspeaking/
loudspeaking
9
VSS
V
oltage
S
ource
S
ource
rce
ce
V
oltage
D
rain
D
rain
A
nalog
G
round
d
Negative Analog Powe Supply
nalog Power
y
18
VDD
Positive Analog Power Supply
ppl
19
AGND
ound
d
inte
Special ground for the inter
internal amplifiers
6
M1
M
icrophone Input
1
rophone
M
icrophone Input
2
M
icrophone Input
3
M
icrophone Input
4
Differential input f the handset microphone (electret)
ferential
for
4
M2
Differen
Different
Differential input for the handset microphone (electret)
5
M3
Differential input for the handsfree microphone (electret)
3
M
M4
Differential input for the handsfree microphone (electret)
17
RO
R
eceive
O
utput to
H
andset
O
scillator Input
Output for driving a dynamic earpiece with an impedance from 150Ω to 300Ω
31
OSC
Input for ceramic resonator 3.58MHz.
Revision 3.4
Page 2 of 19
Data Sheet AS2522B
austriamicrosystems
Pin #
22
21
Symbol
VPP
CM
Function
Loudspeaker Power Supply
High power supply for the output driver stage
C
onverter
M
ake Output
This is an output for controlling the external switching converter. During ringing it converts the
ring signal into a 4V supply voltage
Chip select input of the serial interface. Internal pull-up resistor ( 100kOhm )
29
DI
D
ata
I
nput
Data input of the serial interface. Internal pull-up resistor ( 100kOhm )
30
CLK
Cl
oc
k
Clock input of the serial interface. Internal pull-up resistor ( 100kOhm )
Te
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28
DO
D
ata
O
utput
Data output of the serial interface. If xCS=1 DO is in H
HI-Z state
CS=1
=1
24
23
1
2
LO1
LO2
FT1
FT2
L
oudspeaker
O
utput
1 and 2
Output pins for a 50Ω loudspeaker
aker
r
Analog input pin for connecting a capacitor for offset cancellation.
ting
pacito
aci
fset
Analog input pin for connecting a c
onnecting capacitor for offset cancellation.
ca
ffset cancel
cancella
20
CBN
Analog input pin for connecting a capacitor for background noise monitoring.
or connectin
citor
backgrou
15
16
RECI
Analog input for the hand
t
handsfree receive path. Shoul be connected to RO via coupling
ceive
e
Should
capacitor.
Analog input for receive voice switching path.
or
ce
p
RECV
VSSA
25
Power supply pin for LS1-LS2 output amplifier.
or
-LS2 outp
LS2
32
VSSD
V
oltage
S
ource
S
ource
D
igital
rce
urce
V
oltage
D
rain
D
rain
D
igital
ltag
ltage rai
al
Sup
Su
Negative Digital Power Supply
26
VDDD
ive
P
Positive Digital Power Supply
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xCS
C
hip
S
elect
Data Sheet AS2522B
austriamicrosystems
Detailed Block Diagram
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Revision 3.4
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