STLC30R80 Datasheet, PDF (6/13 Pages) STMicroelectronics – INTEGRATED RINGING SLIC FOR SHORT LOOP APPLICATIONS

STLC30R80
Figure 1. Logic Interface Input Timing
t1
t3
t2
Min.
t1
100ns
t2
100ns
t3
500ns
t4
100ns
t5
100ns
t6
500ns
CSIN
D0.1.2
CSOUT
Note: All measurements are performed with 100pF on outputs
pin and with TTL compatible voltage levels.
the total power consumption in On-hook to 30mW
(typical).
The Off-Hook detection threshold is not program-
mable but defined at a fixed IDETHI = 8mA(max.)
Ground Start.
This mode is selected when the SLIC is adopted
in a system using the Ground Start feature. In this
mode the TIP termination is set in High Imped-
ance (100kΩ) while the RING one is active and
fixed at Vbat +4.8V. In the case of connection of
RING termination to GND the sinked current is
limited to 30mA. When RING is connected to
GND both Off-Hook and Ground-Key detectors
become active. Power dissipation in this mode
with a -48V battery voltage is 100mW.
PROTECTION CIRCUIT
Suggested protection circuit is based on program-
mable Trisils (like LCP1511/2) as shown in Fig.2
and Fig. 3, and the surge current is limited by the
resistors RPT2 and RPR2, which are PTC types ,
protecting the device against both lightning and
power-cross.
METERING PULSE INJECTION
STLC30R80 provides external pins and compo-
nents for Metering Pulse injection. TTXIN pin is
the input for the 12kHz or 16kHz Metering Pulse
injection. This pin also provides a DC constant
current source that is injected into the external
RDA resistor (typ. 10kΩ) connected between
TTXIN pin and AGND. The voltage drop across
TIP and RING line amplifiers and, consequentally
the AC swing available.
When Metering Pulse injection is not used and
voltage drop is not required, TTXIN must be
shorted to AGND and RTTX, RDA and CTTX ex-
ternal components must be removed. The TTX
cancellation is obtained through an external
RTTX and CTTX network connected between
DET, GDK
t4
t6
t5
TTXIN and CAC pins.
Figure1_STLC30R80
MISCELLANEOUS
- Thermal overload: the integrated thermal pro-
tection is activated when Tj reaches 150°C typ.;
the Slic is forced in Power-down mode, DET
and AL are set Low.
- One low cost external transistor allows to re-
duce the power dissipated in the SLIC itself al-
lowing the use of extreme small size package
(TQFP44). The external transistor size/package
can be selected depending on the max. power
requested by the particular application.
EXTERNAL COMPONENTS LIST
To set the SLIC into operation the following pa-
rameters have to be defined:
- The DC feeding resistance "Rfeed" defined as
the resistance of the traditional feeding sys-
tem (most common Rfeed values are: 400,
800, 1000 ohm).
- The AC SLIC impedance at line terminals "Zs"
to which the return loss measurements is re-
ferred. It can be real (typ. 600 ohm) or com-
plex.
- The equivalent AC impedance of the line "Zl"
used for evaluation of the trans-hybrid loss per-
formance (2/4wire conversion). It is usually a
complex impedance.
- The value of the two protection resistors Rp in
series with the line termination.
- The reverse polarity transition time defined as
"∆VTR/∆T".
- The constant current limit value "Ilim".
- Rth: sets the OFF/Hook DETection threshold
Once, the above parameters are defined, it is
possible to calculate all the external components
using the following table.
6/13