as2525 austriamicrosystems, as2525 Datasheet - Page 12

• Manufacturer Part Number: as2525
• Description: Single Chip Handsfree Phone Cmos Integrated Circuit
• Manufacturer: austriamicrosystems

Datasheet AS2525
Table 18: Handsfree attenuation scheme
Revision 2.1
RO
RX > TX_atten
TX_atten > RX
TX_atten > RX
+3dB
LINE
+14dB
Vol max
+8dB
RECV
RECI
FT2
Offset
Offset
comp
comp
Speech
Yes
No
CTXoffset
X
Vol default
Compress
Compress
RX-mode
Transmit
Receive
Mode
Idle
detector
detector
Peak
Peak
Figure 8: Gain transition of voice switching
Figure 7: Signal path of handsfree circuit
0 dB to -20 dB
Vol min
RX-gain
-25 dB
-50 dB
IDLE-mode
switching
Voice
0dB
-10dB
-20dB
-30dB
-40dB
-50dB
-50 dB to -30 dB
-25dB
TX-gain
Gmax = +9dB
Gmin = -21dB … -40dB (VOL)
Gmax = -4dB … +16dB (VOL)
Gmin = -33dB
-25 dB
0 dB
CBN
speech
CBckgnd
adjustable with [V+]/[V-] keys in 8 steps
TX-mode
independent of [V+]/[V-] keys
TX-gain
RX-gain
austriamicrosystems
detector
Peak
middle position
Remark
Compress
Cmicoffset
FT1
Page 12 of 27
Offset
comp
+23dB
+12dB