C2.5X6.3MM-RAD datasheet(26/38 Pages) SILABS

26 / 38 page

Si3226/7

Si3208/9

Preliminary Rev. 0.33

If the Si3226/7 detects a fault condition or overpower

condition on any channel, it automatically sets that

channel to the open state and generates a "power

alarm" interrupt. The interrupt can be masked, but the

automatic transition to open cannot be masked. The

various power alarms and linefeed faults supporting

automatic intervention are described below.

1. LFIC total power exceeded.

2. Power exceeded in one or more transistors of a LFIC

internal transistor group (if capable of measuring

individual power consumption).

3. Excessive foreign current or voltage on TIP and/or

RING.

4. LFIC thermal shutdown event; this event is

automatically performed, and no intervention by the

Si3226/7 is required.

4.5. Thermal Overload Shutdown

If the LFIC die temperature exceeds the maximum

junction temperature threshold, TJmax, of 145 °C or

200 ºC or other programmed temperature threshold

range, the LFIC has the ability to shut itself down to a

low-power state without any assistance from the

Si3226/7. The thermal shutdown circuit contains a

sufficient amount of hysteresis and/or turn-on delay time

so as to remain shut down during a power cross event,

where 50 Hz or 60 Hz, 600 V, is connected to TIP and/

or RING.

4.6. Power Dissipation Considerations

The Dual ProSLIC is designed to source loops up to

20 kft as well as short loop applications. The LFIC

provides all battery sourcing functions and is, therefore,

the determining factor regarding power dissipation in a

specific application. The Dual ProSLIC provides an on-

chip dc-dc controller that can dynamically reduce the

battery supply to ideally match the required line feed

voltage.

4.7. Loop Closure Detection

The Dual ProSLIC provides a completely programmable

loop closure detection mechanism. The loop closure

detection scheme provides two unique thresholds to

allow hysteresis, and also includes a programmable

debounce filter to eliminate false detection. A loop

closure detect status bit provides continuous status, and

a maskable interrupt bit is also provided.

Table 16. Linefeed Operating States

Linefeed State

Description

Open

Output is high-impedance, and all line supervision functions are powered down. Audio is

powered down. This is the default state after powerup or following a hardware reset. This

state can also be used in the presence of line fault conditions and to generate open switch

intervals (OSIs). This state is used in line diagnostics mode as a high-Z state during line-

feed testing. A power fault condition may also force the device into the open state.

Forward Active

Reverse Active

Linefeed circuitry and audio are active. In Forward Active state, the TIP lead is more posi-

tive than the RING lead; in Reverse Active state, the RING lead is more positive than the

TIP lead. Loop closure and ground key detect circuitry are active.

Forward OHT

Reverse OHT

Provides data transmission during an on-hook loop condition (e.g., transmitting caller ID

data between ringing bursts). Linefeed circuitry and audio are active. In Forward OHT

state, the TIP lead is more positive than the RING lead; in Reverse OHT state, the RING

lead is more positive than the TIP lead.

TIP Open

Provides an active linefeed on the RING lead and sets the TIP lead to high impedance

(>400 k

Ω) for ground start operation in forward polarity. Loop closure and ground key

detect circuitry are active.

RING Open

Provides an active linefeed on the TIP lead and sets the RING lead to high impedance

(>400 k

Ω) for ground start operation in reverse polarity. Loop closure and ground key

detect circuitry are active.

Ringing

Drives programmable ringing signal onto TIP and RING leads with or without dc offset.

Line Diagnostics

The channel selected is put into diagnostic mode. In this mode, the selected channel has

special diagnostic resources available.

C2.5X6.3MM-RAD 数据表(PDF) 26 Page - Silicon Laboratories

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