6) RINGING MODE

When the ringing function is selected by the con-

trol processor a low level signal (1.5Vrms) with a

frequency in the range from 16 to 70Hz, perma-

nently applied to the L3092 (pin RGIN), is ampli-

fied and injected in balanced mode into the line

through the L3000N with a super imposed DC

voltage of 24V typ.

This low level sinewave can be obtained also

from COMBO connecting RGIN pin to RX

COMBO output with a decoupling capacitor.

The first and the last ringing cycles are synchro-

nized by the L3092 so that the ringing signal al-

ways starts and stops when the line voltage

crosses zero.

When this mode is activated, the L3000N oper-

ates between the negative and the positive bat-

tery voltages typically - 48V and + 72V. The im-

pedance to the line is just equal to the two

external resistors (typ. 100

Ω).

Ring trip detection is performed autonomously by

the SLIC, without waiting for a command from the

control processor, using a patented system which

allows detection during a ringing burst ; when the

off-hook condition is detected, the SLIC stops the

ringing signal and forces the Conversation Mode.

In this condition, if CS = 0V, the output pin ONHK

goes to 0V.

After the detection of the ONHK = 0, the Card

Controller must set the SLIC in Conversation

Mode to remove the internal latching of the

On/Off hook information.

CONTROL INTERFACE BETWEEN THE SLIC

AND THE CARD CONTROLLER

The SLIC states and functions are controlled by

microprocessor or interface latches of a second

generation combo through seven wires that de-

fine a parallel digital interface.

The seven pins of the digital interface have the

following functions :

- Chip select input (CS)

- Power on/off input (PWON)

- Ring enable input (RNG)

- Automatic SBY input (AUT)

- Limiting current input (LIM)

- On hook/Off hook detection output (ONHK)

- Ground Key detection output (GDK)

The four input pins PWON, RNG, AUT and LIM,

set the status of the SLIC as shown in the follow-

ing table.

The output pin ONHK is equals to 0V when the

equal to + 5V when the line is in On hook condi-

The output pin GDK monitors the ground key

function when the SLIC is in Conversation (CVS)

Mode and the DC operating region (limiting or re-

sistive) in Test (TS) Mode. When the SLIC is in

current) > 12mA, pin GDK is set to 0V ;

Operating Mode

Input Pin

Output Pin

RNG

PWON

AUT

LIM

ONHK

GDK

Conversation 25mA

Conversation 40mA

Conversation 60mA

0

0

0

1

1

1

1

0

0

X

1

0

1 on-hook

0 off-hook

1 Ground key not detected.

0 Ground key detected.

Stand-by

0

0

0

X

Disable

Automatic Stand-by

1

0

1

X

Power-down

1

0

0

X

C1 Comparator Output

Disable

Test Mode

0

0

1

X

1 on-hook

0 off-hook

0 Limiting Region

Ringing (CVS 25mA)

Ringing (CVS 40mA)

Ringing (CVS 60mA)

1

1

1

1

1

1

1

0

0

X

1

0

1 Resistive Region

Disable

N.B. : When Ringing Mode is selected, you must choose also which of the three possible Conversation Modes. The SLIC will automatically

select if Off-Hook condition will be detected during ringing.

lows :

2

The CS input pin allows to connect the I/O pins of

the digital interfaces of many SLIC together.

L3000N - L3092

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