STLC3055N_09 STMICROELECTRONICS [STMicroelectronics], STLC3055N_09 Datasheet - Page 10

• Manufacturer Part Number: STLC3055N_09
• Description: WLL and ISDN-TA subscriber line interface circuit
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Functional description
4.2
4.2.1
4.2.2
4.2.3
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Once the line goes in off-hook condition, the DC/DC converter automatically adjust the
generated battery voltage in order to feed the line with a fixed DC current (programmable via
RLIM) optimising in this way the power dissipation.
Operating modes
Power down
When this mode is selected the SLIC is switched off and the TIP and RING pins are in high
impedance. Also the line detectors are disabled therefore the off-hook condition cannot be
detected.
This mode can be selected in emergency condition when it is necessary to cut any current
delivered to the line.
This mode is also forced by STLC3055N in case of thermal overload (T
In this case the device goes back to the previous status as soon as the junction temperature
decrease under the hysteresis threshold.
No AC transmission is possible in this mode.
High impedance feeding (HI-Z)
This operating mode is normally selected when the telephone is in on-hook in order to
monitor the line status keeping the power consumption at the minimum.
The output voltage in on-hook condition is equal to the self generated battery voltage (-50 V
typ).
When off-hook occurs the DET becomes active (low logic level).
The off-hook threshold in HI-Z mode is the same value as programmed in ACTIVE mode.
The DC characteristic in HI-Z mode is just equal to the self generated battery with
2x(1600 Ω+Rp) in series (see
No AC transmission is possible in this mode.
Figure 3.
Active
DC characteristics and supervision
When this mode is selected the STLC3055N provides both DC feeding and AC
transmission.
DC characteristic in HI-Z mode.
2x(R1+Rp)
Figure
Vbat
IL
3), where Rp is the external protection resistance.
Slope: 2x(R1+Rp)
(R1=1600ohm)
Vbat (-50V)
VL
j
> 140 °C).
STLC3055N