PBL 3786
+ Line
IL
+
20
C +
Speech IC
1
15
2V DC
V
c
-suppy
audio input
22
16
18
22
from Rx
channel
T
X
2,6V
Level shift
21
19
-
+
-
I
+
2
IC
IB
Vs
Z ≈ 0
PBL3786
R
VRE
VR
RE
IR
- Line
V
RE = VR
= IB
+ I C
VR
IL = I R
= 50
= I R
I
x R
VR
x
R
RE
x
V
I = 0
C < 50
I
x
x
C= 0 when
= 50
IR
C
RE
Figure 21. Current biasing regulated by the speech circuit working in parallel with PBL 3786.
+Line
V
IL
IC
I
B
VLine
Handsfree
Circuit
Speech
Circuits
Z ≈ 0
VR
R
IR
ILine
-Line
Figure 23. Schematic of parallel operation.
Figure 22. Speech circuit DC characteristics.
17
RVin
18
15
LS1
LS2
+
-
Ref.
Figure 25. Toneringer threshold circuit
Figure 24. Toneringer frequency generation diagram.
10
Figure 25. Toneringer threshold circuit.
ERICSSON [ ERICSSON ]
