Data Sheet
July 2001
L9311 Full-Feature SLIC with High Longitudinal Balance,
Ringing Relay, and GR-909 Test Access
operating range. During this mode, the NSTAT supervi-
sion output will override the actual hook status and
force an off-hook or logic low.
See the Protection section of this data sheet for more
details on device protection. Please contact your Agere
Account Representative for a recommended secondary
protection device.
Longitudinal balance is consistent with North American
TR-57 requirements.
Transmit and receive gains have been chosen to mini-
mize the number of external components required in
the SLIC-codec ac interface, regardless of the choice
of codec.
The L9311 uses a voltage feed, current sense architec-
ture; thus, the transmit gain is a transconductance. The
L9311 transconductance is set via a single external
resistor, and this device is designed for optimal perfor-
mance with a transconductance set at 300 V/A.
The L9311 offers an option for a single-ended to differ-
ential receive gain of either 8 or 2. These options are
mask programmable at the factory and are selected by
choice of part number.
A receive gain of 8 is more appropriate when choosing
a first-generation type codec where termination imped-
ance, hybrid balance, and overall gains are set by
external analog filters. The higher gain is typically
required for synthesization of complex termination
impedance.
A receive gain of 2 is more appropriate when choosing
a third-generation type codec. Third-generation codecs
will synthesize termination impedance, set hybrid bal-
ance, and set overall gains. To accomplish these func-
tions, third-generation codecs typically have both
analog and digital gain filters. For optimal signal-to-
noise performance, it is best to operate the codec at a
higher gain level. If the SLIC then provides a high gain,
the SLIC output may be saturated causing clipping dis-
tortion of the signal at tip and ring. To avoid this situa-
tion, with a higher-gain SLIC, external resistor dividers
are used. These external components are not neces-
sary with the lower gain offered by the L9311.
The RCVP/RCVN SLIC inputs are floating inputs. If
there is not feedback from RCVP/RCVN to VITR,
RCVP/RCVN may be directly coupled to the codec out-
put. If there is feedback, RCVP/RCVN must be ac-cou-
pled to the codec output.
This device is packaged in a 44-pin PLCC surface-
mount package.
Description
(continued)
For protection against long duration fault conditions,
such as power cross and tip/ring shorts, a thermal shut-
down mechanism is integrated into the device. Upon
reaching the thermal shutdown temperature, the device
will enter an all-off mode. Upon cooling, the device will
re-enter the state it was in prior to thermal shutdown.
Hysteresis is built in to prevent oscillation. During this
mode, the NSTAT supervision output overrides the
actual loop status and forces an off-hook.
The line break switches and tip return switch are
current-limited switches. The current-limit mechanism
limits current through the switch to the specified dc cur-
rent limit under low frequency or dc faults (power cross
and/or tip/ring to ground short) and limits the current to
the specified dynamic current-limit response under
transient faults, such as lightning.
A foldover characteristic is incorporated into the line
break switches within their I-V curve. Under voltage
conditions higher than the normal operating range,
such as may be seen under an extreme lightning or
power cross fault condition, the line break switch will
fold over into a low-current state. This feature allows for
more relaxed specifications on the ring side protector,
thus allowing for higher-voltage ringing signals. (Tip
side protector is limited by the requirements on the tip
return switch.) This feature is part of the overall device
protection scheme.
This device uses a window comparator to force an all-
off condition if the battery drops below, or rises above,
a specified threshold.
Upon loss of V
BAT1
, the L9311 will automatically enter
an all-off mode. The device will enter this mode if the
magnitude of the battery drops below a nominal 15 V
and will remain in this mode until the magnitude of the
battery rises above a typical 20 V. During this mode,
the NSTAT supervision output will override the actual
hook status and force an off-hook or logic low.
When the device is in the scan mode, because of the
design of the scan clamp circuit, common-mode cur-
rent can be forced into or out of the battery supply.
Because of this, and depending upon power supply
design, the magnitude of the battery may rise above
the maximum operating condition during extended lon-
gitudinal currents or during a power cross fault condi-
tion. To prevent excess current from being forced into
or out of the battery, if the magnitude of the battery
rises typically above 75 V to 80 V, the device will enter
an all-off state. The device will remain in the all-off state
until the magnitude of the battery drops into the normal
Agere Systems Inc.
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