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SSI78Q902Ethernet Twisted-Pair MediaAttachment UnitLINK INTEGRITY TEST FUNCTIONFigure 5 is a state diagram of the SSI 780902 linkIntegrity Test Function. The link Integrity Test is usedto determine the status of the receive side twisted paircable. The link integrity test is enabled when the LI pinis tied high. When enabled, the receiver recognizes linkintegrity pulses which are transmitted in the absence ofreceive traffic. If no serial data stream or link integritypulses are detected within 50 - 150 ms, the chip entersa link fail state and disables the transmit and loopbackfunctions. The SSI 780902 ignores any link integritypulse with intervals less than 2 - 7 ms. The SSI 780902will remain in the link fail state until it detects either aserial data packet or two or more link integrity pulses.1Power On,-OUTPUT IDLETEST MODEThe SSI 780902 Test mode is selected when a 2 to2.5 MHz clock is input on the MOO mode select pin.Test mode sets the internal counter chains to run at1024 times their normal speed. The maximum transmittime, unjab time, link Integrity timing and LED timingare reduced by a factor of 1024. During test operation,10 MHzand20 MHz signals areoutputonthe PRC andSOE pins, respectively. When Test mode is selected,the SOE function cannot be disabled. I n Test mode thePRC function can be disabled by the LI pin. Jabbercanbe disabled by setting MD1 = O.,P ower 0 n•NO OUTPUT+ DO = ActiveOUTPUT DETECTEDt 00= IdleSOE WAIT TESTStart_SOE_Test_Waie Timer.. I t SOE Test W ait_Timer_Done·XMIT = Disable XMIT= Enabl eSOE TESTStart_SOE_ Tese TimerCI = SOESOE_ Test_ Timer_Done J, DO = ActiveNONJABBER OUTPUTStarcXMIT _Max_Timer.. DO = Idlel, DO = Active'XMIT _Max_ Timer_D one-JAB ~XMIT = DisableLPBK = DisableCI = SQE.. 00= IdleUNJAB WAITStart_Unjab_ TimerXMIT = DisableLPBK = DisableCI = SQEIUnjab Timer DoneIDO = Active'Unjab_ Timer_NoCDoneFIGURE 3: SaE Test FunctionFIGURE 4: Jabber Control Function7-4