STLC3085

Functional description

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Functional description

The STLC3085 is a device specifically developed for WLL VoIP and ISDN-TA applications.

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

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

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

It can be set in three different operating modes via the D0, D1, D2 pins of the control logic

interface (0 to 3.3V 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 3.3V and 5V 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.

Table 6.

SLIC operating modes.

3.1

DC/DC converter

The DC/DC converter controller is driving 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 device operation.

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

PGND supply (FlyBack) or to VPOS supply (BuckBoost) allows to fix the maximum allowed

input peak current.

This feature is implemented in order to avoid overload on Vpos supply in case of line transient

(ex. ring trip detection). Typ. value of 130m

Ω guarantees an average current consumption from

Vpos < 600mA for BuckBoost configuration and < 1.25A for Fly- Back configuration.

PD

D0

D1

D2

Operating Mode

000

X

Power Down

1

0

0

X

H.I. Feeding (HI-Z)

1

0

1

0

Active Normal Polarity

1

0

1

1

Active Reverse Polarity

Not used

Not used

1

1

0

0/1

Ring (D2 bit toggles @ fring)