AS2525F AMSCO [austriamicrosystems AG], AS2525F Datasheet - Page 10

• Manufacturer Part Number: AS2525F
• Description: Single-Chip Handsfree Phone CMOS Integrated Circuit
• Manufacturer: AMSCO [austriamicrosystems AG]

Datasheet AS2525
Side-Tone
A good side-tone cancellation can be achieved by using
the following equation:
This is assuming that the side-tone reference resistor, R2
(between LI and STB) is 300
Transmit Path
The gain of the M1/M2 —> LS path is default set to 37 dB.
This gain can be changed from 30 dB to 45 dB in 1 dB
steps by set-up programming.
Table 8: Handset Tx gain setting
The input is differential with an impedance of 10 k . The
soft clip circuit limits the output voltage swing at pin LS to
2 V
Table 9: Handset Tx soft clipping selection
There is optional LLC for this path.
The gain of the M3/M4 —> LS path is default set to 46 dB.
This gain can be changed from 39 dB to 54 dB in 1 dB
steps by set-up programming.
Revision 2.1
PEAK
Digit
Key
(x)
[0]
[1]
[2)
[3]
[4]
[5]
[6]
[7]
[0]
[1]
[PG] + [0] + (Password) + [#] + [4] + (digit) + [PG]
[PG] + [0] + (Password) + [0] + [1] + (x) + [PG]
Z
when activated.
BAL
Z
LINE
/Z
Handset Tx Soft Clipping
Disabled
Enabled (2 V
LINE
Figure 5: Side-tone balance
Tx Gain (dB)
M1/2 to LS
= 10
Z
BAL
30
31
32
33
34
35
36
37
PEAK
)
and R1 is 30
R2 = 300 ohm
[M1]
[M2]
[M3]
[M4]
[M5]
[M6]
Key
(x)
R1 = 30 ohm
[8]
[9]
Tx Gain (dB)
M1/2 to LS
.
38
39
40
41
42
43
44
45
Table 10: Handsfree Tx gain setting
The input is differential with an impedance of 10 k .
The soft clip circuit limits the output voltage swing at pin
LS to 2 V
Table 11: Handsfree Tx soft clipping selection
There is no LLC option for this path.
Receive Path
The gain of the LS —> RO receive path is default set to 1
dB. This gain can be changed from -6 dB to 9 dB in 1 dB
steps by set-up programming.
Table 12: Handset Rx gain setting
When the handset volume control is enabled (see Table 3:
Parameter settings), the user can also change the gain
within this range in 4 dB steps via the [V+]/[V-] keys. The
default receive gain in handset and headset mode must lie
between position 5 and 9 for correct operation of the
volume control. The receive input is the differential signal
of RI and STB. The soft clip circuit limits the output voltage
at RO to 1 V
shock.
Digit
Key
Key
(x)
[0]
[1]
[2]
[3]
[4]
[5]
[6]
[7]
(x)
[0]
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[
[0]
[1]
PG] + [0] + (Password) + [9] + [2] + (digit) + [PG]
[PG] + [0] + (Password) + [0] + [3] + (x) + [PG]
[PG] + [0] + (Password) + [0] + [2] + (x) + [PG]
PEAK
PEAK
Handsfree Tx Soft Clipping
Disabled
Enabled (2 V
when activated
Tx Gain (dB)
Rx Gain (dB)
M3/4 to LS
. It prevents harsh distortion and acoustic
LS to RO
39
40
41
42
43
44
45
46
-6
-5
-4
-3
-2
-1
0
1
PEAK
.
)
[M1]
[M2]
[M3]
[M4]
[M5]
[M6]
[M1]
[M2]
[M3]
[M4]
[M5]
[M6]
Key
Key
(x)
[8]
[9]
(x)
[8]
[9]
Rx Gain (dB)
Tx Gain (dB)
M3/4 to LS
LS to RO
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