Data Sheet
July 2001
Forward Battery SLIC and Ringing Relay for TR-57 Applications
L9312 Line Interface and Line Access Circuit
Agere Systems Inc.
11
State Definitions
Primary Control Modes
Powerup, Forward Battery
I
Normal talk and battery feed state.
I
Pin PT is positive with respect to pin PR.
I
All ac transmission and dc feed circuits are powered
up.
I
On-hook transmission is enabled.
I
Thermal shutdown is active.
I
Battery window comparator sense shutdown is on.
I
Switch break switches (SW1 and SW2) are closed,
and ring access switches (SW3 and SW4) are open.
I
V
BAT1
is applied to tip and ring during on-hook condi-
tions.
I
Automatic battery switch selects V
BAT1
or V
BAT2
dur-
ing off-hook conditions.
I
All supervision circuits except for ring trip detector
are active.
I
NSTAT represents the loop closure detector status.
Scan
I
Scan clamp circuitry is active.
I
Loop closure is active.
I
All ac transmission, dc feed, and other supervision
circuits, including ring trip, are shut down.
I
Thermal shutdown is active.
I
Battery window comparator sense shutdown is on.
I
On-hook transmission is disabled.
I
Pin PT is positive with respect to PR, and V
BAT1
is
applied to tip/ring.
I
Switch break switches (SW1 and SW2) are closed,
and ring access switches (SW3 and SW4) are open.
I
NSTAT represents the loop closure detector status.
Ringing
I
Switch break switches (SW1 and SW2) are open,
and ring access switches (SW3 and SW4) are
closed.
I
Tip/ring drive amplifiers are powered down.
I
Ring trip circuit is active.
I
Loop supervision and common-mode current detec-
tors are powered down.
I
NSTAT represents the ring trip detector status.
Disconnect
—
Break Before Make
I
The tip and ring amplifiers are turned off to conserve
power.
I
Break switches (SW1 and SW2) are open, and ring
access switches (SW3 and SW4) are open. This
mode is also used as a transitional mode to achieve
break-before-make switching from the power ring to
active or scan mode.
I
All supervision circuits are powered down; NSTAT
overrides the actual loop condition and is forced high
(on-hook).
Reset
I
Selection of device reset via the RESET pin will set
the device into the disconnect break-before-make
state.
Special States
Thermal Shutdown
I
Not controlled via truth table inputs.
I
This mode is caused by excessive heating of the
device, such as may be encountered in an extended
power cross situation.
I
Upon reaching the thermal shutdown temperature,
the device will enter an all-off mode.
I
Upon cooling, the device will re-enter the state it was
in prior to thermal shutdown.
I
Hysteresis is built in to prevent oscillation. In this
mode, supervision output NSTAT is forced low
(off-hook) regardless of loop status or if the discon-
nect logic state is selected.