ksz8041tl-ftl Micrel Semiconductor, ksz8041tl-ftl Datasheet - Page 34

• Manufacturer Part Number: ksz8041tl-ftl
• Description: 10base-t/100base-tx/100base-fx Physical Layer Transceiver
• Manufacturer: Micrel Semiconductor

Micrel, Inc.
RMII Back-to-Back Mode
The KSZ8041FTL and KSZ8041TL are configured in RMII Back-to-Back mode after it is power-up or reset with the
following:
RMII Back-to-Back mode provides the option to disable and tri-state the transmitter on both copper and fiber sides if the
cable is disconnected on the copper side. On the copper side, RXD2 (pin 21) indicates if there is energy detected at the
receive inputs of the UTP port. RXD2 outputs a low if there is no energy detected (cable disconnected), and outputs a
high if there is energy detected (cable connected). The RXD2 output is connected thru an inverter to drive TXD2 (pin 38)
input high to disable and tri-state the transmitters for both copper and fiber sides.
The TXD3 and TXD2 pins should be pulled down with 1K resistors, and RXD3 and RXD2 pins should be left floating, if
they are not used.
April 2007
•
•
•
CONFIG[2:0] (pins 27, 41, 40) set to ‘101’ for both KSZ8041FTL and KSZ8041TL.
A common 50 MHz reference clock connected to REFCLK (pin 15) of both KSZ8041FTL and KSZ8041TL.
RMII signals connected as shown in the following table between KSZ8041FTL in fiber mode and KSZ8041TL in
copper mode.
Pin Name
CRSDV
RXD1
RXD0
TXEN
TXD1
TXD0
KSZ8041FTL in fiber mode
Pin Number
Table 13. RMII Signal Connection for RMII Back-to-Back Mode
27
22
23
34
36
35
Pin Type
Output
Output
Output
Input
Input
Input
34
Pin Name
CRSDV
TXEN
TXD1
TXD0
RXD1
RXD0
KSZ8041TL in copper mode
Pin Number
34
36
35
27
22
23
Pin Type
Output
Output
Output
Input
Input
Input
M9999-042707-1.1
KSZ8041TL/FTL