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PDF AS2523 Data sheet ( Hoja de datos )
| Número de pieza | AS2523 | |
| Descripción | Telephone Line Interface and Speakerphone Circuit | |
| Fabricantes | austriamicrosystems AG | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de AS2523 (archivo pdf) en la parte inferior de esta página. Total 19 Páginas | ||
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Telephone Line Interface and
Speakerphone Circuit
AS2523, AS2524, AS2524B
austriamicrosystems
PRELIMINARY DATA SHEET
Key Features
- Line/Speakerphone circuit on a 28-pin CMOS-IC, simple
inventory: same die for AS2523/24 and AS2523/24B
- Serial I/F on AS2523, parallel I/F on AS2524
- Enhanced voice switching
- Background noise monitoring
- Tx- and Rx-gain programmable on AS2523 only
- Digital volume control of Rx signals on AS2523 only
- DC characteristic programmable on AS2523 only
- Dual softclipping in handset mode on AS2523 only
- Dual softclipping in handsfree mode on AS2523 only
- Loudspeaker amplifier for loudhearing and handsfree
- Supply voltage generation for external circuitry
- Automatic line loss compensation on AS2523 / 24B only
- Real and complex impedance selectable by external
components
- Side tone adaptation selectable by external components
- Unique EMC performance
- Operating range from 15mA to 100mA (down to 5mA
with reduced performance)
- Few external components
Block Diagram
General Description
AS2523/24 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
softclipping, line loss compensation and Rx-volume control
for handset and handsfree operation. It shall act as an a/b-
line powered device, which is controlled by a CPU via a
serial interface on AS2523 or a standard dialler via a
parallel interface on AS2524 and AS2524B.
Applications
Enhanced handsfree feature phones with CallerID and
extended displays. The AS2524 and AS2524B are
developed to interface with common Taiwanese dialers.
Package
Available in 28-pin SOIC or die
Revision 1.12, Preliminary
Page 1 of 19
1 page  
Data Sheet AS2523, AS2524, AS2524B
austriamicrosystems
Functional Description
DC conditions
The normal operating mode is from 15mA to 100mA. An
operating mode with reduced performance is from 5mA to
15mA. In the line hold range from 0mA to 5mA the device
is in a power down mode.
The DC characteristic is determined by the voltage at LI-
pin and a 30Ω resistor between LI- and LS-pin. It can be
calculated by the following equation: VLS = VLI + ILine *
30Ω. VLI can be programmed to be 3.5V or 4.5V.
2/4 wire conversion
AS2523/24 has built in two Wheatstone bridges with one
common ground. This provides a maximum of
independence of AC-impedance and side tone from each
other. One can adapt side tone without changing the AC-
impedance.
AC-impedance
The AC-impedance of AS2523/24 is set to t.m. 1000Ω.
With the external capacitor at CI-pin it can be programmed
complex. With an external resistor of approx. 1.5kΩ
connected to the LS-pin it can be programmed to 600Ω.
Side Tone
A good side tone cancellation can be achieved by using the
following equation:
ZBAL/ZLINE = 10
Transmit path
The gain of the M1/M2 → LS is set to +37dB. This gain
can be changed by programming on AS2523 from +30dB to
+45dB in 1dB steps (Register Txgain), on AS2524 / 24B it
is set to +37dB per default. The input is differential with an
impedance of 10kΩ. The soft clip circuit limits the output
voltage at LS to 2Vp. There is LLC for this path.
voice switching circuit
The gain of the M3/M4 → LS is set to +46dB.
This gain can be changed by programming from +39dB to
+54dB in 1dB steps on AS2523. The input is differential
with an impedance of 10kΩ. The soft clip circuit limits the
output voltage at LS to 2Vp. There is no LLC for this path.
Receive path
The gain of the LS → RO receive path is set to +7.5dB.
This gain can be changed by programming from –7.5dB to
+7.5dB in 1dB steps (Register Rxgain). The receive input
is the differential signal of RI and STB. The soft clip circuit
limits the output voltage at RO to 1Vp. It prevents harsh
distortion and acoustic shock. There is LLC for this path.
The gain of the LS → LO receive path is set to +32dB.
This gain can be changed by programming from +19dB to -
34dB in 1dB steps. The user can also change the gain via
Register Handsfree receive end gain (See section
"Handsfree"). The receive input is the differential signal of
RI and STB. The soft clip circuit limits the output voltage at
LO to 1.1Vp. It prevents harsh distortion and acoustic
shock. There is optional LLC for this path.
Line Loss Compensation (AS2523, AS2524B)
- programmable on AS2523
- not activated at AS2524
- permanently activated at AS2524B
When it is activated, the transmit and receive gains for
both I/O’s are decreased by 6dB at line currents from
20mA to 50mA or from 45mA to 75mA.
Handsfree
The handsfree function allows voice communication without
using the handset (full 2-way speaker phone). Two voice
controlled attenuators prevent acoustic coupling between
the loudspeaker and the microphone. The voice switching
circuit has three states, namely idle, transmit or receive. In
receive mode the attenuation of the receive path and the
transmit path can be controlled by Register Handsfree
receive end gain between 0dB and -20dB. The following
table shows how voice switching is controlled
TX_atten
RX
Voice
switching
speech
Backgnd
noise
monitor
Revision 1.12, Preliminary
Page 5 of 19
5 Page 
Data Sheet AS2523, AS2524, AS2524B
austriamicrosystems
Parallel Interface on AS2524 and AS2524B
Input Signal on Pin
XPD xMute
00
00
01
01
10
10
11
11
HF Mode
0 Power down
1 Power down
0 Power down
1 Power down
0 Tone mode
1 Tone mode
0 Handset mode
1 Handsfree mode
Power down mode
For low power consumption the analog part is turned off during activated power down mode. The Power down mode is used
during Flash and Pulse dialing and for On-hook operation.
Handset mode
Speech mode is Handset mode (M1-M2, RO active; LO deactivated)
Parameter
AS2524
AS2524B
LI Voltage
4.5V
4.5V
LLC
No LLC
LLC high (45mA to 75mA)
TX-Gain
+37dB
+43dB
RX-Gain
+7.5dB
+7.5dB
Rx-Softclip
Off
Off
Tx-Softclip
Off
Off
Tone Off Off
Handsfree mode
Speech mode is Handsfree mode (M3-M4, RO active; LO active)
Parameter
AS2524
AS2524B
LI Voltage
4.5V
4.5V
LLC
No LLC
LLC high (45mA to 75mA)
HF TX-Gain
+46dB
+52dB
HF RX-Gain
+34dB
+34dB
Rx-Softclip
Off
Off
Tx-Softclip
Off
Off
Tone Off Off
BNM On On
Revision 1.12, Preliminary
Page 11 of 19
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet AS2523.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| AS2520 | Telephone Speech Circuit with Loudhearing and Handsfree | austriamicrosystems AG |
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| AS2520BP | Telephone Speech Circuit with Loudhearing and Handsfree | austriamicrosystems AG |
| AS2520BT | Telephone Speech Circuit with Loudhearing and Handsfree | austriamicrosystems AG |
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