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
2016 Microchip Technology Inc. DS00002199A-page 23
KSZ8081RNA/RND
Power can be reduced further by extending the time interval between transmissions of link pulses to check for the pres-
ence of a link partner. The periodic transmission of link pulses is needed to ensure two link partners in the same low
power state and with auto MDI/MDI-X disabled can wake up when the cable is connected between them.
By default, energy-detect power-down mode is disabled after power-up.
3.10.3 POWER-DOWN MODE
Power-down mode is used to power down the KSZ8081RNA/RND device when it is not in use after power-up. It is
enabled by writing a ‘1’ to Register 0h, Bit [11].
In this mode, the KSZ8081RNA/RND disables all internal functions except the MII management interface. The
KSZ8081RNA/RND exits (disables) power-down mode after Register 0h, Bit [11] is set back to ‘0’.
3.10.4 SLOW-OSCILLATOR MODE
Slow-oscillator mode is used to disconnect the input reference crystal/clock on XI (Pin 8) and select the on-chip slow
oscillator when the KSZ8081RNA/RND device is not in use after power-up. It is enabled by writing a ‘1’ to Register 11h,
Bit[5].
Slow-oscillator mode works in conjunction with power-down mode to put the KSZ8081RNA/RND device in the lowest
power state, with all internal functions disabled except the MII management interface. To properly exit this mode and
return to normal PHY operation, use the following programming sequence:
1. Disable slow-oscillator mode by writing a ‘0’ to Register 11h, Bit [5].
2. Disable power-down mode by writing a ‘0’ to Register 0h, Bit [11].
3. Initiate software reset by writing a ‘1’ to Register 0h, Bit [15].
3.11 Reference Circuit for Power and Ground Connections
The KSZ8081RNA/RND is a single 3.3V supply device with a built-in regulator to supply the 1.2V core. The power and
ground connections are shown in Figure 3-9 and Table 3-6 for 3.3V VDDIO.
FIGURE 3-9: KSZ8081RNA/RND POWER AND GROUND CONNECTIONS
VDDIO
KSZ8081RNA/RND
GND
3.3V
VDDA_3.3
0.1μF
1
VDD_1.2
2
FERRITE
BEAD
14
22
PADDLE
2.2μF
0.1μF22μF
0.1μF22μF