Preliminary
Pin Description
Pin #
1
Symbol
CS2
Type
DO
Description
Chip Select 2
Chip select signal for external LCD driver circuit or 2 mA LED
If signal is not activated, a pull down resistor ( 100 k
Ω
) is inserted.
AS2525
2
DPn
DO
D
ial
P
ulse Output
Digital output which holds the line during off-hook operation or pulls low during
break periods of pulse dialling and flash.
3
HF
DI
H
ands
F
ree Switch Input
This is an Schmitt-trigger input that is pulled high to enable handsfree
operation.
4
HS
DI
H
andSet Switch Input
This is an Schmitt-trigger input that is pulled high by the hook switch to enable
handset or headset operation.
5
6
7
8
9
10
11
12
FT1
FT2
M4
M2
M3
M1
STB
CS
AI
AI
AI
AI
AI
AI
AI
AO
Analogue input pin for connecting a capacitor for offset cancellation.
Analogue input pin for connecting a capacitor for offset cancellation.
M
icrophone Input
4
Differential input for the handsfree microphone (electret).
M
icrophone Input
2
Differential input for the handset microphone (electret).
M
icrophone Input
3
Differential input for the handsfree microphone (electret).
M
icrophone Input
1
Differential input for the handset microphone (electret).
S
ide
T
one
B
alance Input
Analogue input for side tone cancellation network.
C
urrent
S
hunt Control Output
N-channel open drain output to control the external high power shunt transistor
for synthesising ac- and dc-impedance, modulation of line voltage and shorting
the line during make periods of pulse dialling.
13
14
15
16
V
SS
LI
RI
SS
Supply
AI
AI
AO
V
oltage
S
ource
S
ource
Negative Power Supply.
L
ine
I
nput
Analogue input used for power extraction and line current sensing.
R
eceive
I
nput
Analogue input for ac-separated receive signal.
S
upply
S
ource Control Output
N-channel open drain output to control the external high power source
transistor for supplying (Vpp) the loudspeaker amplifier in off-hook
loudspeaking/handsfree mode.
17
LS
AI
L
ine Current
S
ense Input
Analogue input for sensing the line current.
Rev. 1.3
Page 2
May 1999
AMSCO [ AUSTRIAMICROSYSTEMS AG ]
