stlc3075 STMicroelectronics, stlc3075 Datasheet - Page 8

• Manufacturer Part Number: stlc3075
• Description: Integrated Pots Interface For Home Access Gateway And Wll
• Manufacturer: STMicroelectronics

Functional description
3.2
3.2.1
3.2.2
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The self generated battery voltage is set to a predefined value in on-hook state.
The typical value of -50V can be adjusted via one external resistor (RF1). When RING mode
is selected this typical value is increased to -70V.
Once the line goes in off-hook condition, the DC/DC converter automatically adjusts the
generated battery voltage in order to feed the line with a fixed DC current (programmable via
RLIM) optimizing 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. The line detectors are also disabled therefore the off-hook condition cannot be
detected.
The power down mode can be selected in emergency condition when it is necessary to cut
any current delivered to the line.
The power down mode is also forced by STLC3075 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.
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 (-50V
typical).
When off-hook occurs the DET becomes active (low logic level).
The off-hook threshold value in HI-Z mode is the same as the programmed value in ACTIVE
mode.
The DC characteristics in HI-Z mode are equal to the self generated battery with
2x(1600 +Rp) in series (see
No AC transmission is possible.
Figure 3.
DC characteristics in HI-Z mode.
2x(R1+Rp)
Figure 3
Vbat
IL
), where Rp is the external protection resistance.
Slope: 2x(R1+Rp)
(R1=1600ohm)
Vbat (-50V)
VL
j
STLC3075
> 140°C).