AM79R70-1SC AMD [Advanced Micro Devices], AM79R70-1SC Datasheet - Page 13

• Manufacturer Part Number: AM79R70-1SC
• Description: Ringing Subscriber Line Interface Circuit
• Manufacturer: AMD [Advanced Micro Devices]

RING-TRIP COMPONENTS
R
Ring waveform rise time ≈ 0.214 • (R
For a 1.25 crest factor @ 20 Hz, tr ≈ 10 mS.
∴ (R
C
R
R
C
SLEW
SLEW
RT1
RT2
RT
where R
SLEW
=
=
=
, C
should be changed if a different crest factor is desired.
1.5 µF
320 CF
12 kΩ
SLEW
= 150 kΩ, C
LRT
•
= Loop-detection threshold resistance for ring trip and CF = Crest factor of ringing signal (≈ 1.25)
Battery
•
------------------------------------------------------------------------------------------------------------------------------------ -
Vbat 5
0
R
SLEW
L
–
–
= 0.33 µF.)
b
a
(
24 µA 320 CF
I
L
SLEW
•
Feed current programmed by R
V
• C
BAT1
•
A
B
Figure 2. Ringing Waveforms
SLEW
Figure 3. Feed Programming
•
(
R
) ≈ tr.
This is the best time for
switching between RINGING
and other states for minimizing
detect switching transients.
LRT
SLIC
SLIC Products
+
150
+
2R
RSN
RDC
F
)
)
DC1
•
(
R
and R
LRT
+
DC2
150
+
R
R
2R
DC2
DC1
F
)
Ringing Reference
(Input to R
A(TIP)
B(RING)
C
SLEW
DC
)
13