STLC30R81 データシートの表示（PDF） - STMicroelectronics

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STLC30R81

INTEGRATED RINGING SLIC FOR SHORT LOOP APPLICATIONS

STMicroelectronics 

Figure 7. Phone detection Diagram

Active R.P.

DET

DET

STLC30R81

HiZ

Phone

T>4ms

No Phone

T<2ms

Short Circuit

DET signal pin changes its logical level depending on the presence (or not) of short circuit at the output of the

Line Card (See Tab.5).

Table 5. Short Circuit Detection

Control Word

D0

D1

D2

D3

1

1

1

1

Short Circuit

0

DET

No Short Circuit

1

Loop back

The test is aimed at cheking detection and feeding circuitry functionalities as described in fig. 8. The external

resistor RLPCK is closed internally between TIP and RING and emulates the phone resistance. Starting from

ACTIVE mode, when loop back mode is selected DET pin will change its level.

If DET pin is low it means that detection and feeding circuits work properly. If DET remains high it means that a

failure has been detected.

Table 6. Loop Back Detection

Control Word

D0

D1

D2

D3

0

0

1

1

DET

Good

Fail

0

1

Figure 8. loop back detection diagram

Active

Loop Back

Active

DET

Protection Mode

Suggested protection circuit is based on programmable LCP1521S Trisil and the surge current is limited by the

resistors RPT2 and RPR2, which are PTC types, protecting the device against both lightning and power-cross.

Thermal overload: the integrated thermal protection is activated when Tj reaches 150°C typ.; the Slic is forced

in Power-down mode, DET and AL are set Low.

For external applications, two diodes 1N4148 are suggested (Pls. see application diagram).

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