A parallel interface allow to control the operation

of STLC30R80 through a control bus:

- D0 D1 D2 latched input bits defining the Slic

operation mode

- DET and GDK/AL , tri-state outputs, signal the

status of the loop: On/Off-Hook and Ground-Key.

Pin GDK/AL goes low also when the device

thermal protection is activated or a line fault (Tip to

Ring, Tip and/or Ring to Ground or VBAT) is

detected (flowing current

≥ 7.5mA).

-CSIN: chip select for input bits, active Low,

strobes the data present on the control bus into

the internal latch.

- CSOUT: chip select for output bits ; active Low ,

when high DET and GDK/AL goes tri-state.

D0 D1 D2 CSIN and CSOUT inputs are provided

with a 15

µA pull-down current to prevent uncon-

trolled conditions in case the control bus goes

floating.

According to the table 6 operating modes can be

set:

1) Power-Down.

2) Stand-By.

3) Active N.P.

4) Active R.P.

5) Ringing

6) High Impedance Feeding.

Power-Down

It’s an idle state characterised by a very low

power consumption; any functionality is disabled.

It can be set during out of service periods just to

reduce the power consumption.

It is worth noticing that two other conditions can

set the Slic in idle state but with some differences

as reported in the table:

Idle State

DET

GDK/AL

Power Down

Disable

Disable

Reset

Disable

Disable

Thermal Alarm

Low

Low

Stand-By.

Mode selected in On-Hook condition when high

immunity to common mode currents is needed for

the DET bit.

To reduce the current consumption, AC feedback

loop is disabled and only DET and GDK/AL de-

tectors are active.

DC current is limited at 16mA (not programma-

ble); feeding characteristic shown in fig. a.

The voltage drop in on-hook condition is 7.8V.

Active

Mode selected to allow voice signal transmission.

When in ACTIVE mode the voltage drop in on-

hook condition is 7.8V in order to allow proper on-

hook transmission (Fig. b).

Resistive Region is programmable by means of

CONTROL INTERFACE

INPUTS

OPERATING MODE

OUTPUTS

D0

D1

D2

DET

(Active Low)

GDK/AL

(Active Low)

0

0

0

0

1

1

1

0

0

1

1

0

1

1

0

1

0

1

0/1

1

0

Power down

Stand-by

Active N.P.

Active R.P.

Ringing

High Impedance Feeding

Ground Start

disable

off/hk

off/hk

off/hk

ring/trip

off/hk

off/hk

disable

gnd-key

gnd-key

gnd-key

disable

disable

gnd-key

16mA

D98TL307

I

V

Figure a: STLC30R80 DC Characteristic in

Stand-By Mode.

5

D99TL435

I

V

Figure b. STLC30R80 DC Characteristic in

Active Mode.

STLC30R80

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