KSZ9031RNX(2012) Просмотр технического описания (PDF) - Micrel
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KSZ9031RNX Datasheet PDF : 75 Pages
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Micrel, Inc.
KSZ9031RNX
LinkMD® Cable Diagnostic
The LinkMD function uses time domain reflectometry (TDR) to analyze the cabling plant for common cabling problems,
such as open circuits, short circuits, and impedance mismatches.
LinkMD operates by sending a pulse of known amplitude and duration down the selected differential pair, then analyzing
the polarity and shape of the reflected signal to determine the type of fault: open circuit for a positive/non-inverted
amplitude reflection and short circuit for a negative/inverted amplitude reflection. The time duration for the reflected signal
to return provides the approximate distance to the cabling fault. The LinkMD function processes this TDR information and
presents it as a numerical value that can be translated to a cable distance.
LinkMD is initiated by accessing register 12h, the LinkMD – Cable Diagnostic register, in conjunction with register 1Ch,
the Auto MDI/MDI-X register. The latter register is needed to disable the Auto MDI/MDI-X function before running the
LinkMD test. Additionally, a software reset (Reg. 0h, bit [15] = 1) should be performed before and after running the
LinkMD test. The reset helps to ensure the KSZ9031RNX is in the normal operating state before and after the test.
NAND Tree Support
The KSZ9031RNX provides parametric NAND tree support for fault detection between chip I/Os and board. NAND tree
mode is enabled at power-up/reset with the MODE[3:0] strap-in pins set to ‘0100’.
Table 11 lists the NAND tree pin order.
Pin
LED2
LED1/PME_N1
TXD0
TXD1
TXD2
TXD3
GTX_CLK
TX_EN
RX_DV
RX_CLK
INT_N/PME_N2
MDC
MDIO
CLK125_NDO
Description
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Output
Table 11. NAND Tree Test Pin Order for KSZ9031RNX
October 2012
31
M9999-103112-1.0
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