am79r70 Advanced Micro Devices, am79r70 Datasheet - Page 13

• Manufacturer Part Number: am79r70
• Description: Ringing Subscriber Line Interface Circuit
• Manufacturer: Advanced Micro Devices

RING-TRIP COMPONENTS
R
Ring waveform rise time
For a 1.25 crest factor @ 20 Hz, tr
C
R
R
C
SLEW
SLEW
RT1
RT2
RT
(R
where R
SLEW
=
=
=
, C
should be changed if a different crest factor is desired.
1.5 F
300 CF
12 k
SLEW
= 150 k , C
LRT
= Loop-detection threshold resistance for ring trip and CF = Crest factor of ringing signal ( 1.25
Battery
----------------------------------------------------------------------------------------------------------------------------------------- -
Vbat 3.5
0
R
SLEW
L
–
0.214 (R
= 0.33 F.)
b
a
–
15 A 300 CF
I
L
10 mS.
SLEW
Feed current programmed by R
V
BAT1
C
A
B
SLEW
Figure 2. Ringing Waveforms
Figure 3. Feed Programming
P R E L I M I N A R Y
)
This is the best time for
switching between RINGING
and other states for minimizing
detect switching transients.
R
SLIC
LRT
tr.
SLIC Products
+
150
+
2R
RSN
RDC
F
DC1
and R
R
LRT
DC2
+
150
R
R
+
DC2
DC1
2R
F
Ringing Reference
(Input to R
B(RING)
A(TIP)
C
SLEW
DC
)
13