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 20 2016 Microchip Technology Inc.
The following programming action and register settings are used for local loopback mode:
For 10/100 Mbps loopback:
Set Register 0h,
Bit [14] = 1 // Enable local loopback mode
Bit [13] = 0/1 // Select 10 Mbps/100 Mbps speed
Bit [12] = 0 // Disable auto-negotiation
Bit [8] = 1 // Select full-duplex mode
Follow the steps below if you don’t want the frames go out from the copper port in the local loopback.
1. Set register 1Fh bit [3] to ‘1’ to disable the transmitter.
2. Run local loopback test as above.
3. Set register 1Fh bit [3] to ‘0’ to enable the transmitter.
3.7.2 REMOTE (ANALOG) LOOPBACK
This loopback mode checks the line (differential pairs, transformer, RJ-45 connector, Ethernet cable) transmit and
receive data paths between the KSZ8081RNA/RND and its link partner, and is supported for 100BASE-TX full-duplex
mode only.
The loopback data path is shown in Figure 3-8.
1. The Fast Ethernet (100BASE-TX) PHY link partner transmits frames to the KSZ8081RNA/RND.
2. Frames are wrapped around inside the KSZ8081RNA/RND.
3. The KSZ8081RNA/RND transmits frames back to the Fast Ethernet (100BASE-TX) PHY link partner.
The following programming steps and register settings are used for remote loopback mode:
1. Set Register 0h,
Bits [13] = 1 // Select 100Mbps speed
Bit [12] = 0 // Disable auto-negotiation
Bit [8] = 1 // Select full-duplex mode
Or just auto-negotiate and link up at 100BASE-TX full-duplex mode with the link partner.
2. Set Register 1Fh,
Bit [2] = 1 // Enable remote loopback mode
FIGURE 3-8: REMOTE (ANALOG) LOOPBACK
RJ-45
RJ-45
CAT-5
(UTP)
KSZ8081RNA/RND
100BASE-TX
LINK PARTNER
AFE
(ANALOG)
PCS
(DIGITAL)
RMII