Datasheet
Table Of Contents
- 1.0 Introduction
- 2.0 Pin Description and Configuration
- 3.0 Functional Description
- 3.1 10BASE-T/100BASE-TX Transceiver
- 3.2 RMII Interface
- 3.3 Back-to-Back Mode – 100 Mbps Copper Repeater
- 3.4 MII Management (MIIM) Interface
- 3.5 Interrupt (INTRP)
- 3.6 HP Auto MDI/MDI-X
- 3.7 Loopback Mode
- 3.8 LinkMD® Cable Diagnostic
- 3.9 NAND Tree Support
- 3.10 Power Management
- 3.11 Reference Circuit for Power and Ground Connections
- 3.12 Typical Current/Power Consumption
- 4.0 Register Descriptions
- 5.0 Operational Characteristics
- 6.0 Electrical Characteristics
- 7.0 Timing Diagrams
- 8.0 Reset Circuit
- 9.0 Reference Circuits — LED Strap-In Pins
- 10.0 Reference Clock - Connection and Selection
- 11.0 Magnetic - Connection and Selection
- 12.0 Package Outline
KSZ8081RNA/RND
DS00002199A-page 16 2016 Microchip Technology Inc.
3.3 Back-to-Back Mode – 100 Mbps Copper Repeater
Two KSZ8081RNA/RND devices can be connected back-to-back to form a managed 100BASE-TX copper repeater.
3.3.1 RMII BACK-TO-BACK MODE
In RMII back-to-back mode, a KSZ8081RNA/RND interfaces with another KSZ8081RNA/RND to provide a 100 Mbps
copper repeater solution.
The KSZ8081RNA/RND devices are configured to RMII back-to-back mode after power-up or reset, and software pro-
gramming, with the following:
• A common 50 MHz reference clock connected to XI (Pin 8)
• Register 1Fh, Bit [7] programmed to ‘1’ to select RMII – 50 MHz clock mode for KSZ8081RNA
KSZ8081RND is set to RMII – 50 MHz clock mode as the default after power up or hardware reset.
• Register 16h, Bits [6] and [1] programmed to ‘1’ and ‘1’, respectively, to enable RMII back-to-back mode.
• RMII signals connected as shown in Table 3-2.
FIGURE 3-4: KSZ8081RNA/RND AND KSZ8081RNA/RND RMII BACK-TO-BACK COPPER
REPEATER
TABLE 3-2: RMII SIGNAL CONNECTION FOR RMII BACK-TO-BACK MODE (100BASE-TX
COPPER REPEATER)
KSZ8081RNA/RND (100BASE-TX Copper)
[Device 1]
KSZ8081RNA/RND (100BASE-TX Copper)
[Device 2]
Pin Name Pin Number Pin Type Pin Name Pin Number Pin Type
CRS_DV 15 Output TXEN 19 Input
RXD1 12 Output TXD1 21 Input
RXD0 13 Output TXD0 20 Input
TXEN 19 Input CRS_DV 15 Output
TXD1 21 Input RXD1 12 Output
TXD0 20 Input RXD0 13 Output
KSZ8081RNA/RND
(COPPER MODE)
RXP/RXM
TXP/TXM
RxD
TxD
RxD
TxD
OSC
XI
XI
50MHz
TXP/TXM
RXP/RXM
(COPPER MODE)
KSZ8081RNA/RND