L9215A/G
Short-Loop Sine Wave Ringing SLIC
Data Sheet
September 2001
is input to the device’s RINGIN input. 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.
Supervision
The L9215 offers the loop closure and ring trip supervi-
sion functions. Internal to the device, the outputs of
these detectors are multiplexed into a single package
output, NSTAT. Additionally, a common-mode current
detector for tip or ring ground detection is included for
ground key applications.
Various crest factors are shown below for illustrative
purposes.
80
60
Loop Closure
40
The loop closure has a fixed typical 10.5 mA on- to off-
hook threshold in the active mode and a fixed 11.5 mA
on- to off-hook threshold from the scan mode. In either
case, there is a 2 mA hysteresis with VCC = 5 V and a
1 mA hysteresis with VCC = 3.3 V.
20
0
–20
–40
–60
–80
0.00 0.04 0.08 0.12 0.16 0.20
0.02 0.06 0.10 0.14 0.18
Ring Trip
TIME (s)
12-3346a (F)
The ring trip detector requires only a single-pole filter at
the input, minimizing external components. An R/C
combination of 383 kΩ and 0.1 µF, for a filter pole at
5.15 Hz, is recommended.
Note: Slew rate = 5.65 V/ms; trise = tfall = 23 ms; pwidth = 2 ms;
period = 50 ms.
Figure 9. Ringing Waveform Crest Factor = 1.6
The ring trip threshold is internally fixed as a function of
battery voltage and is given by:
80
60
RT (mA) = 67 * {(0.0045 * VBAT1) + 0.317}
where:
40
RT is ring trip current in mA.
20
VBAT1 is the magnitude of the ring battery in V.
There is a 6 mA to 8 mA hysteresis.
0
–20
–40
–60
Tip or Ring Ground Detector
–80
0.00 0.04 0.08 0.12 0.16 0.20
0.02 0.06 0.10 0.14 0.18
In the ground key or ground start applications, a com-
mon-mode current detector is used to indicate either a
tip- or ring-ground has occurred (ground key) or an off-
hook has occurred (ground start). The detection thresh-
old is set by connecting a resistor from ICM to VCC.
TIME (s)
12-3347a (F)
Note: Slew rate = 10.83 V/ms; trise = tfall = 12 ms; pwidth = 13 ms;
period = 50 ms.
Figure 10. Ringing Waveform Crest Factor = 1.2
170 x VCC/RICM (kΩ) = ITH (mA)
Additionally, a filter capacitor across RICM will set the
time constant of the detector. No hysteresis is associ-
ated with this detector.
Voltage applied to the load may be increased by using
a filtered square wave input to produce a lower crest
factor trapezoidal power ring signal at tip and ring.
Power Ring
The device offers a ring mode, in which a balanced
power ring signal is provided to the tip/ring pair. During
the ring mode, a user-supplied low-voltage ring signal
Agere Systems Inc.
27
AGERE [ AGERE SYSTEMS ]
