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PDF AS2522BF Data sheet ( Hoja de datos )
| Número de pieza | AS2522BF | |
| Descripción | Telephone Line Interface and Speakerphone Circuit | |
| Fabricantes | austriamicrosystems AG | |
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Telephone Line Interface and
Speakerphone Circuit
AS2522B
austriamicrosystems
DATA SHEET
Key Features
- 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
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
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
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. Furthermore the AS2522 incorporates a
DTMF, FSK transmitter, single tone and ringer tone
generator.
AS2522 allows to use an off-the-shelf microprocessor
without special blocks and functions for telephone
applications. DTMF, FSK transmitter, single tone and ringer
tone generator can be controlled via the serial interface as
well as the gain settings in handset and handsfree mode.
Applications
Enhanced handsfree feature phones with CallerID and
extended displays.
Package
Available in 32-pin TQFP
Revision 3.4
Page 1 of 19
1 page  
Data Sheet AS2522B
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
AS2522 has a built-in dual Wheatstone bridge 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 AS2522 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 from +30dB to +45dB in
1dB steps (Register Txgain). 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.
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. 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 +1dB.
This gain can be changed by programming from -6dB to
+9dB 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 → LO1/LO2 receive path is set to
+29dB. This gain can be changed by programming from
+22dB to -37dB in 1dB steps. The user can also change
the gain via Register VOL (See section "Handsfree"). The
receive input is the differential signal of RI and STB. The
soft clip circuit limits the output voltage at LO1 of LO2 to
1Vp. It prevents harsh distortion and acoustic shock. There
is optional LLC for this path.
Line Loss Compensation
The line loss compensation is programmable (Register
0x0C). 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 VOL between
0dB and -20dB. The following table shows how voice
switching is controlled
Revision 3.4
Page 5 of 19
5 Page 
Data Sheet AS2522B
austriamicrosystems
Electrical characteristics
Electrical characteristics are measured with the Test Circuit
application. Typical mean values will not be tested.
Absolute maximum ratings
Positive Supply Voltage
Input Current
Input Voltage (LS)
Input Voltage (LI, CS)
Input Voltage (STB, RI)
Digital Input Voltage
Electrostatic Discharge (HBM 1.5kΩ-100pF)
Storage Temperature
-0.3V <= VDD <= 7V
+/- 25mA
-0.3V <= Vin <= 12V
-0.3V <= Vin <= 8V
-2V <= Vin <= VDD+0.3V
-0.3V <= Vin <= VDD+0.3V
+/- 1000V
-65°C to +125°C
Recommended operating conditions
Supply Voltage (generated internally)
Operating Temperature
3V <= VDD <= 5V
-25°C to +70°C
DC characteristics
ILine=15mA w/o operation of any additional external
circuitry, unless other specified
Symbol
Parameter
IDDS
Operating Current
IDDH
Operating Current
VLI Line Voltage LIVolt=0
Line Voltage LIVolt=1
IOL Output Current, Sink
CS,SS
Conditions
Speech Mode
Handsfree Mode
15mA<=ILINE<=100mA
VOL=0.4V
Min Type Max Units Test
3 6 mA Y
7
10 mA
Y
3.2 3.5 3.8
4.2 4.5 4.8
V
V
Y
Y
1 mA N
Revision 3.4
Page 11 of 19
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet AS2522BF.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| AS2522B | Telephone Line Interface and Speakerphone Circuit | austriamicrosystems AG |
| AS2522BF | Telephone Line Interface and Speakerphone Circuit | austriamicrosystems AG |
| AS2522BQ | Telephone Line Interface and Speakerphone Circuit | austriamicrosystems AG |
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