STLC3075

Functional description

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Functional description

The STLC3075 is a device specifically developed for WLL VoIP and ISDN-TA applications. It

is based on a SLIC core, on purpose optimized for these applications, with the addition of a

DC/DC converter controller to meet the WLL and ISDN-TA design requirements.

The SLIC performs the standard feeding, signalling and transmission functions.

STLC3075 can be set in three 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.

4.1

DC/DC converter

The DC/DC converter controller drives an external power MOS transistor N-Ch plus

transformer (Flyback configuration) or P-Ch plus inductor (Buckboost configuration), in order

to generate the negative battery voltage needed for the device operation.

The DC/DC converter controller is synchronized with an external CLK (125 kHz typ.) or with

input peak current.

transient (ex. ring trip detection). The 110 m

Ω typical value guarantees an average current

Table 6.

SLIC operating modes

PD

D0

D1

D2

Operating mode

00

0

X

Power down

1

0

0

X

H.I. feeding (HI-Z)

1

0

1

0

Active normal polarity

10

11

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)