le9531cmqc Zarlink Semiconductor, le9531cmqc Datasheet - Page 26

• Manufacturer Part Number: le9531cmqc
• Description: Ringing Subscriber Line Interface Circuit
• Manufacturer: Zarlink Semiconductor

Supervision
The Le9531 device offers the loop closure and ring trip supervision functions. Internal to the device, the outputs of
these detectors are multiplexed into a single package output, NSTAT. The ring trip detector is valid on NSTAT
during the ring state, and loop closure detector is valid on NSTAT during active and on-hook transmission states.
Additionally, common-mode current is detected for ground start applications. This status is output onto NSTAT and
is valid during ground start mode.
Loop Closure
The loop closure has a fixed typical 11.2 mA on-hook to off-hook threshold in the Active and Scan states. In either
case, there is a 2.2-mA hysteresis.
For systems designed to set the SLIC in Scan state while the loop is in on hook condition and to set the SLIC in
Active state when the loop condition becomes off hook and to operate with a less negative potential battery it is
desirable to set the SLIC in the Active state first before ramping the battery from a more negative potential to a less
negative potential for enhanced system performance.
Ring Trip
The ring trip detector requires only a single-pole filter at the input, minimizing external components. An R/C
combination of 383 k and 0.1 µF, for a filter pole at 4.15 Hz, is recommended.
The ring trip threshold is internally fixed as a function of battery voltage and is given by the following:
where:
The ring trip detection hysteresis is about 10mA.
Ground Start
In the ground start applications, the loop closure detector is also used to indicate ring-ground has occurred. During
ground start mode, loop current will be common mode, rather than differential as in loop start mode. Thus, in
ground start the threshold of the loop closure detector is reduced by one half the threshold seen in the loop start
mode. This output is seen at the NSTAT output pin.
Power Ring
The device offers a ring state, in which a balanced power ring signal is provided to the tip/ring pair. During the ring
state, a user-supplied low-voltage ring signal is input to the device’s RINGP/N inputs. This signal is amplified to
produce the balanced power ring signal. The user may supply a sine wave input, PWM input, or a square wave to
produce sinusoidal or trapezoidal ringing at tip and ring.
R
R
V
T
T
BAT
(mA) = 33 * {(0.0045 * V
is ring trip current in mA.
is the magnitude of the ring battery in volts.
BAT
) + 1.146}
Zarlink Semiconductor Inc.
Le9531
26
Data Sheet