Lucent Technologies Inc.
17
Data Sheet
October 1998
Relay, and Protector (SRP) for Long Loop and TR-57 Applications
L8574D Resistive Subscriber Line Interface Circuit (SLIC), Ring
Operating States
(continued)
Disconnect State
I
Forward disconnect state.
I
The receive transmission path is powered down; the
transmit path is powered up.
I
The current limiter is powered down and disabled.
I
SW1, SW2, and SW3 are open.
I
Pins PT, PR, and V
BF
are high impedance
(>100 k
).
I
NSTAT is forced high (on-hook).
Alternate Talk State
I
Alternate talk state.
I
The battery feed is connected to the high battery
supply (V
BAT1
).
I
The receive and transmit transmission paths are both
powered up.
I
The current limiter is powered up and active.
I
SW1 and SW2 are closed; SW3 is open.
I
NSTAT reflects the status of the switchhook detector.
Talk State
I
Normal talk state.
I
The battery feed is connected to the high battery
supply (V
BAT2
).
I
The receive and transmit transmission paths are both
powered up.
I
The current limiter is powered up and active.
I
SW2 is closed; SW1 and SW3 are open.
I
NSTAT reflects the status of the switchhook detector.
Scan Current-Limit State
I
Alternate on-hook supervision state.
I
Same as scan state but with the current limiter pow-
ered up and active.
I
The receive transmission path is powered down; the
transmit path is powered up.
I
SW1 is closed; SW2 and SW3 are open.
I
NSTAT reflects the status of the switchhook detector.
Ringing State
I
Normal ringing state.
I
The receive and transmit transmission paths are both
powered down.
I
SW3 is closed; SW1 and SW2 are open.
I
The current limiter is powered down and disabled.
I
NSTAT reflects the status of the ring trip detector.
On-Hook Transmission State
I
Normal on-hook transmission state.
I
The battery feed is connected to the high battery
supply (V
BAT1
).
I
The receive and transmit transmission paths are both
powered up.
I
The current limiter is powered down and disabled.
I
A 10 mA dc bias current flows out of the Ring current
driver into PR, and a 5 mA dc bias current flows into
the Tip current driver from PT (the switchhook detec-
tor is adjusted to compensate for this dc bias cur-
rent).
I
SW1 and SW2 are closed; SW3 is open.
I
NSTAT reflects the status of the switchhook detector.