APPENDIX C

Power Down,

Power Down

HI-Z Feeding,

HI-Z Feeding

HI-Z Feeding,

Power Down

Power Down,

HI-Z Feeding

Line 1 State,

Line 2 State

Act Off Hook,

Ic Feeding

Ic Feeding,

Act Off Hook

Ringing,

Ringing

Ringing,

Ic Feeding

Ic Feeding,

Ringing

Ic Feeding,

Act On Hook

Act On Hook,

Ic Feeding

Act On Hook,

Act On Hook

SW

routine

(*)

P1=1

P2=0

P1=P2=1

P1=0, P2=1

Tj>Tth

Ring Burst

Line 1,

D2=0/1

Ring Burst

Line 2,

D2=0/1

D0=D1=P1=P2=0

Line1Off Hook

Line1,

Off Hook

Line1On Hook,

P1=1, P2=0

Line2Off Hook

Line2Off Hook

Line2On Hook

P1=P2=1

P1=P2=1

Ring Burst

Line1 and 2,

D2=0/1

Line1

On Hook,

Ring Pause

Ring Pause

Ring Pause

Ring Burst

Ring Burst

Ring Burst

Ring Trip

Detection

Line 1

Ring Trip

Detection

Line 2

Line2On Hook,

P1=0, P2=1

Line1Off Hook

Line1Off Hook

Line2 Off Hook

Line2 Off Hook

Off Hook

Detection

Ring Trip

Detection

Figure C1. Typical state diagram for the STLC3065 operation

Note: all state transitions are under the microprocessor control.

(*) = When the ringing signal is sent to both lines, the STLC3065 is not able to detect the answering line. To detect the answering line, a SW

routine is needed that disables first the line 1 (forcing P1=0) and then the line 2 ( forcing P2=0) so as to detect which line is in Off Hook

condition.

The On Hook condition is declared when it persists for T>Tref.

Ic Feeding state is referred to a constant feeding current applied to the local loop and equal to 300

µA.

STLC3065

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