stlc30r81 STMicroelectronics, stlc30r81 Datasheet - Page 9

• Manufacturer Part Number: stlc30r81
• Description: Integrated Ringing Slic For Short Loop Applications
• Manufacturer: STMicroelectronics

Figure 7. Phone detection Diagram
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
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
Figure 8. loop back detection diagram
Protection Mode
Suggested protection circuit is based on programmable LCP1521S Trisil and the surge current is limited by the
resistors R
Thermal overload: the integrated thermal protection is activated when T
in Power-down mode, DET and AL are set Low.
For external applications, two diodes 1N4148 are suggested (Pls. see application diagram).
D0
D0
1
0
D1
D1
PT2
1
0
Control Word
Control Word
and R
D2
D2
PR2
1
1
DET
DET
Active R.P.
, which are PTC types, protecting the device against both lightning and power-cross.
Active
DET
D3
D3
1
1
Loop Back
Short Circuit
T<2ms
Good
T>4ms
0
0
HiZ
Active
DET
DET
j
reaches 150°C typ.; the Slic is forced
Phone
No Phone
No Short Circuit
Fail
1
1
STLC30R81
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