MB86961A Datasheet, PDF (13/29 Pages) Fujitsu Component Limited. – UNIVERSAL INTERFACE FOR 10BASET

MB86961A
data or link pulses are received within 96 to 128 ms, the
polarity is reset to the default non-flipped condition. If
Link Integrity Testing is disabled, polarity detection is
based only on received data. Polarity correction is always
enabled.
COLLISION DETECTION FUNCTION
The collision detection function operates on the twisted-
pair side of the interface. A collision is defined as the
Power On
OUTPUT IDLE
(DO = Active)
OUTPUT DETECTED
(DO = Idle)
SQE WAIT TEST
Start_SQE_Test_Wait_Timer
(XMIT = Disable)
(SQE_Test_Wait_Timer_Done)•
(XMIT = Enable)
SQE TEST
Start_XMIT_Max_Timer
CI = SQE
(SQE_Test_Timer_Done)
Figure 8. SQE Function
simultaneous presence of valid signals on both the TPI
circuit and the TPO circuit. The MB86961A reports colli-
sions to the back-end via the COL pin. If the TPI circuit
becomes active while there is activity on the TPO circuit,
the TPI data is passed to the back-end over the RXD cir-
cuit, disabling normal loopback. Figure 9 is a state dia-
gram of the MB86961A collision detection function.
Refer to Electrical Characteristics for collision detection
and COL/CI output timing.
LOOPBACK FUNCTION
The MB86961A provides the normal loopback function
specified by the 10BASE-T standard for the twisted-pair
port. The loopback function operates in conjunction with
the transmit function. Data transmitted by the back-end is
internally looped back within the MB86961A from the
TXD pin through the Manchester encoder/decoder to the
RXD pin and returned to the back-end. The “normal”
loopback function is disabled when a data collision
occurs, clearing the RXD circuit for the TPI data. Normal
loopback is also disabled during link fail and jabber
states.
The MB86961A also provides additional loopback func-
tions. An external loopback mode, useful for system-level
testing, is controlled by pin 21 (LEDC). When LEDC is
tied low, the MB86961A disables the collision detection
and internal loopback circuits to allow external loopback
or full-duplex operation. The MB86961A provides loop-
back functions controlled by pin 22 (LBK). When the TP
port is selected and LBK=1, TP loopback is “forced,”
overriding collisions on the TP circuit. When LBK=0,
normal loopback is in effect.
(DO= Active)•
(TPI = Idle)•
(XMIT = Enabled)
A
Power On
IDLE
(TPI = Active)
OUTPUT
TPO = DO
DI = DO
A
(DO= Idle) +
(XMIT = Disabled)
INPUT
(DO= Active)•
(TPI = Active)•
(XMIT = Enabled)
(DO= Active)•
(TPI = Active)•
(XMIT = Enabled)
DI = TPI
COLLISION
A
TPO = DO
DI = TPI
CI = SQE
(TPI = Idle)
(DO= Active)•
(TPI = Idle)
(DO= Idle)
Figure 9. Collision Detection Function
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