E-STLC3055N View Datasheet(PDF) - STMicroelectronics
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Description
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E-STLC3055N Datasheet PDF : 34 Pages
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STLC3055N
4
Functional description
Functional description
The STLC3055N is a device specifically developed for WLL VoIP and ISDN-TA applications.
It is based on a SLIC core, on purpose optimised for these applications, with the addition of
a DC/DC converter controller to fulfil the WLL and ISDN-TA design requirements.
The SLIC performs the standard feeding, signalling and transmission functions.
It can be set in four different operating modes via the D0, D1, D2 pins of the control logic
interface (0 to 3.3 V logic levels). The loop status is carried out on the DET pin (active low).
The DET pin is an open drain output to allow easy interfacing with both 3.3 V and 5 V logic
levels.
The four possible SLIC’s operating modes are:
● Power down
● High impedance feeding (HI-Z)
● Active
● Ringing
Table 6 shows how to set the different SLIC operating modes.
Table 6. SLIC operating modes.
PD D0 D1 D2
Operating mode
0
0
0
X Power down
1
0
0
X H.I. feeding (HI-Z)
1
0
1
0 Active normal polarity
1
0
1
1 Active reverse polarity
1
1
1
0 Active TTX injection (N.P.)
1
1
1
1 Active TTX injection (R.P.)
1
1
0
0/1 Ring (D2 bit toggles @ fring)
4.1
DC/DC converter
The DC/DC converter controller is driving an external power MOS transistor (P-channel) in
order to generate the negative battery voltage needed for device operation.
The DC/DC converter controller is synchronised with an external CLK (125 kHz typ.) or with
an internal clock generated when the pin CLK is connected to CVCC. One sensing resistor
in series to Vpos supply allows to fix the maximum allowed input peak current. This feature
is implemented in order to avoid overload on Vpos supply in case of line transient (ex. ring
trip detection).
The typical value is obtained for a sensing resistor equal to 110 mΩ that will guarantee an
average current consumption from Vpos < 700 mA. When in on-hook the self generated
battery voltage is set to a predefined value.
This value can be adjusted via one external resistor (RF1) and it is typical -50 V. When
RING mode is selected this value is increased to -70 V typ.
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