as2504 austriamicrosystems, as2504 Datasheet - Page 5

• Manufacturer Part Number: as2504
• Description: Cordless Telephone, Answering Machine Line Interface
• Manufacturer: austriamicrosystems

Preliminary Data Sheet
The gain of the ATI1 —> LS is set to 6dB. The
input is unbalanced with an impedance of
25k . There is no softclipping.
The gain of the ATI2 —> LS is set to 20dB.
The input is unbalanced with an impedance of
100k . There is no softclipping.
Intercom path
The gain of the ATI3 —> ROH1 is set to 6dB.
The input is unbalanced with an impedance of
100k . There is no softclipping.
The gain of the ATI3 —> ROH2 is set to 12dB.
The input is unbalanced with an impedance of
100k . There is no softclipping.
The gain of the M1/M2 —> ARO1 is set to
23dB. The input is differential with an
impedance of 20k . The soft clip circuit limits
the output voltage at ARO1 to 0.4V
attack time is 30µs/6dB and the decay time is
20ms/6dB.
The gain of the M3/M4 —> ARO1 is set to
29dB. The input is differential with an
impedance of 10k . The soft clip circuit limits
the output voltage at ARO1 to 0.4V
attack time is 30µs/6dB and the decay time is
20ms/6dB.
Receive path
The gain of the LS —> ROH1 receive path is
set to 3dB. The receive input is the differential
signal of RI and STB. The soft clip circuit limits
the output voltage at ROH1 to 0.7V
prevents harsh distortion and acoustic shock.
There is volume control and LLC for this path.
The gain of the LS —> ROH2 receive path is
set to 9dB. The receive input is the differential
signal of RI and STB. The soft clip circuit limits
the output voltage at ROH2 to 1.4V
prevents harsh distortion and acoustic shock.
There is volume control and LLC for this path.
The gain of the LS —> ARO1 receive path is
set to 3dB. The receive input is the differential
signal of RI and STB. There is no softclipping,
no LLC and no volume control for this path.
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Rx volume control
The volume control is available for LS —>
ROH1 and LS —> ROH2. It can be decreased
by 6dB and increased by 8dB in 2dB steps
from the default levels as described in the last
paragraph. It remains in the pre-set position as
long as VDD does not decrease less than 2.2V
Line Loss Compensation
The line loss compensation is a pin option.
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 when the
LLC-pin is connected to AGND and from 45mA
to 75mA when the LLC-pin is connected to
VDD. The line loss compensation is
deactivated when LLC-pin is connected to
VSS.
Digital interface
The selection of the available signal paths
must be set via the digital control pins. The
following modes are possible:
HSS: bit
AUX0: bit
TX0: bit
0
0
0
1
1
0
1
0
1
1
0
0
1
0



TX1: bit
RX0: bit
AUX1: bit
0
0
1
0
1
0
0
1
1
1
1
1
0
0



HSS: bit
LS —> ROH1
LS —> ROH2
ATI3 —> ROH1
ATI3 —> ROH2
HSS: bit
0
1
X
X
X
X
X
X

0
1

M1/M2 —> LS
M3/M4 —> LS
ATI1 —> LS
ATI2 —> LS
MUTE
August 1998
MUTE
M1/M2 —>
ARO1
M3/M4 —>
ARO1
LS —>
ARO1
MUTE
AS2504