Micrel, Inc.
KSZ8765CLX
A LinkMD® Example
The following is a sample procedure for using LinkMD® on Port 3 and Port 4.
//Disable Auto-MDI/MDI-X and force to MDI-X mode
//’w’ is WRITE the register. ‘r’ is READ register below
w 3d 04
w 4d 04
//Set internal registers temporary by indirect registers, adjust for LinkMD
w 6e a0
w 6f 4d
w a0 80
//Enable LinkMD testing with fault cable for Port 1, Port 2, Port 3 and Port 4
w 3a 10
w 4a 10
//Wait until Port Register Control 8 bit [4] returns a ‘0’ (self-clear)
//Diagnosis results
r 3a
r 3b
r 4a
r 4b
//For example on Port 3, the result analysis based on the values of the register 0x3a and 0x3b
//The register 0x3a bits [6-5] are for the open or the short detection.
//The register 0x3a bit [0] + the register 0x3b bits [7-0] = CDT_Fault_Count [8-0]
//The distance to fault is about 0.4 x (CDT_Fault_Count [8-0])
On-Chip Termination and Internal Biasing
The KSZ8765CLX reduces the board cost and simplifies the board layout by using on-chip termination resistors for all
ports and RX/TX differential pairs without external termination resistors. The combination of the on-chip termination and
the internal biasing will save more PCB space and power consumption in system, compared with using external biasing
and termination resistors for multiple ports’ switches because the transformers do not consume power anymore. The
center taps of the transformer should not need to be tied to the analog power.
July 23, 2014
25
Revision 1.0