STLC3075(2005) Ver la hoja de datos (PDF) - STMicroelectronics
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STLC3075 Datasheet PDF : 26 Pages
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STLC3075
The output voltage in on-hook condition is equal to the self generated battery voltage (-50V 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(1600Ω+Rp) in series
(see fig. 4), where Rp is the external protection resistance.
No AC transmission is possibile.
Figure 4. DC Characteristic in HI-Z Mode.
IL
Vbat
2x(R1+Rp)
Slope: 2x(R1+Rp)
(R1=1600ohm)
VL
Vbat (-50V)
3.2.3 Active
3.2.3.1 DC Characteristics & Supervision
When this mode is selected the STLC3075 provides both DC feeding and AC transmission.
The STLC3075 feeds the line with a constant current fixed by RLIM (20mA to 40mA range). The on-hook
voltage is typically 40V allowing on-hook transmission; the self generated Vbat is -50V typ.
If the loop resistance is very high and the line current cannot reach the programmed constant current feed
value, the STLC3075 behaves like a 40V voltage source with a series impedance equal to the protection
resistors 2xRp (typ. 2x50Ω). Fig. 5 shows the typical DC characteristic in ACTIVE mode.
The line status (on/off hook) is monitored by the SLIC’S supervision circuit. The off-hook threshold can be
programmed via the external resistor RTH in the range from 5mA to 9mA.
Independently on the programmed constant current value, the TIP and RING buffers have a current
source capability limited to 80mA typ.
Figure 5. DC characteristic in ACTIVE mode
IL
Ilim
(20 to
40mA)
2Rp
VL
10V
Vbat (-50V)
Moreover the power available at Vbat is controlled by the DC/DC converter that limits the peak current
drawn from the Vpos supply. The maximum allowed current peak is set by RSENSE resistor.
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