U4091BM-N Datasheet, PDF (21/38 Pages) ATMEL Corporation – PROGRAMMABLE TELEPHONE AUDIO PROCESSOR

U4091BM-N
Figure 12. Dial Tone Detector
IN
+
OUT
-
35 mV
to mode
I4 ^control
VM
DTD
Figure 13. Background Noise Monitor
VB
TLDR
(TLDT)
-
+
+
-
-
+
56 kΩ
33 kΩ
36 mV
VM
BNMR
(BNMT)
1 µF
I4
(I3)
Figure 14. Generation of Control Voltage (CT) for Mode Switching
CT
CCT
I _RX
10mA ITX
10mA ^IFI
I _SI
VM VM
AFS
control
to
attenuators
Control
circuit
4
I _1-4
Dial tone det.
21
4666B–CORD–08/04