AS2520B AMSCO [austriamicrosystems AG], AS2520B Datasheet - Page 2

• Manufacturer Part Number: AS2520B
• Description: Telephone Speech Circuit with Loudhearing and Handsfree
• Manufacturer: AMSCO [austriamicrosystems AG]

Preliminary
Pin Description
Rev. 5.1
Pin #
10
11
12
13
14
15
16
17
18
1
2
3
4
5
6
7
8
9
Name
RTH
STB
LLC
A
V
CM
RO
LSI
MT
V
V
PD
HS
LS
LO
LE
CI
TI
GND
SSP
DD
PP
Supply
Supply
Supply
Supply
Type
AO
AO
AO
AO
AI
AI
AI
DI
AI
DI
AI
DI
DI
DI
DI
Description
Line Current Sense Input
This input is used for sensing the line current.
Complex Impedance Input
Input pin for the capacitor in the complex impedance.
Receive Output
This is the output for driving a dynamic earpiece with an impedance of 140
to 300 ohm.
Positive Voltage Supply
This is the supply pin for the circuit.
Analogue Ground
This pin is the analogue ground for the amplifiers.
Side Tone Balance Input
This is the input for the side tone cancellation network.
Line Loss Compensation Selection Pin
LLC = V
LLC = A
LLC = V
Loudspeaker Amplifier Input
This is the input for applying the receive signal to the loudspeaker
amplifier.
Tone Input
This switchable input is intended for transmitting DTMF or other signals
like messages on TAMs (Telephone Answering Machines) onto the line in
off-hook conditions and when in ringing mode to apply a PDM signal to the
loudspeaker (see also table 1).
Receive Threshold Input
The sensibility of the receive peak detector can be adjusted by applying
the signal from RO to the RTH input through a voltage divider.
Converter Make Output
This is an output for controlling the external switching converter. It
converts the ring signal into a 4V supply voltage and is activated when PD
= high and HS, LE, MT = low.
Loudspeaker Power Supply
High power supply for the output driver stage.
Output for Loudspeaker
Output pin for an ac coupled 32
Negative High Power Supply
This pin is the negative high power supply for the loudspeaker amplifier.
Mute Input
Dialling mute input (see also table 1).
MT = V
MT = V
Power Down Input
Input for powering down the speech circuit and loudhearing/handsfree
(see table 1).
Loudhearing Enable Input
Input for enabling loudhearing/handsfree, active high (see table 1).
Handset Switch Input
This is an input that is pulled high by the hook switch (handset) or µC
when off-hook (see table 1).
DD
SS
DD
GND
SS
: Tx and Rx channels not muted.
: Tx and Rx channels muted;
:
: High range
: Low range
No regulation
Page 2
-6 dB from 45 mA to 75 mA;
-6 dB from 20 mA to 50 mA;
gain independent of line current;
(25 to 50
)loudspeaker.
AS2520/21/20B/21B
May 1999