STLC3075

Functional description

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Once the ring trip is detected, the DET output is activated (logic level low). At this point the

card controller or a simple logic circuit stops the D2 toggling in order to effectively

disconnect the ring signal and then set the STLC3075 in the proper operating mode

(normally active).

Ring level in presence of more telephones in parallel

As already mentioned in the previous section, the maximum current that can be drawn from

available at the self generated negative battery.

If for any reason the ringer load is too low, the self generated battery drops in order to keep

the power consumption to the fixed limit and consequently the ring voltage level is also

reduced.

limited to around 900 mApk, which correspond to an average current of 700 mA max. In this

condition the STLC3075 can drive up to 3REN with a ring frequency fr=25 Hz

(1REN = 1800

Ω + 1.0 µF, European standard).

In order to drive up to 5REN (1REN= 6930

Ω + 8 µF, US standard) it is necessary to modify

the external components as follows:

CREV = 15nF; RD = 2.2 k

Ω; R

and USA standards. In order to drive 5REN (US standard) it is necessary to modify the