KSZ8081MNXCA [MICREL]
10Base-T/100Base-TX Physical Layer Transceiver;
| 型号： | KSZ8081MNXCA |
| 厂家： | 
MICREL SEMICONDUCTOR |
| 描述： | 10Base-T/100Base-TX Physical Layer Transceiver |
| 文件： | 总69页 (文件大小：1501K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
KSZ8081MNX/KSZ8081RNB
10Base-T/100Base-TX
Physical Layer Transceiver
Revision 1.4
General Description
Features
The KSZ8081 is a single-supply 10Base-T/100Base-TX
Ethernet physical-layer transceiver for transmission and
reception of data over standard CAT-5 unshielded twisted
pair (UTP) cable.
• Single-chip 10Base-T/100Base-TX IEEE 802.3
compliant Ethernet transceiver
• MII interface support (KSZ8081MNX)
• RMII v1.2 Interface support with a 50MHz reference
clock output to MAC, and an option to input a 50MHz
reference clock (KSZ8081RNB)
The KSZ8081 is a highly-integrated PHY solution. It
reduces board cost and simplifies board layout by using
on-chip termination resistors for the differential pairs and
by integrating a low-noise regulator to supply the 1.2V
core.
• Back-to-back mode support for a 100Mbps copper
repeater
• MDC/MDIO management interface for PHY register
configuration
The KSZ8081MNX offers the Media Independent Interface
(MII) and the KSZ8081RNB offers the Reduced Media
Independent Interface (RMII) for direct connection with
MII/RMII-compliant Ethernet MAC processors and
switches.
• Programmable interrupt output
• LED outputs for link, activity, and speed status indication
• On-chip termination resistors for the differential pairs
• Baseline wander correction
• HP Auto MDI/MDI-X to reliably detect and correct
straight-through and crossover cable connections with
disable and enable option
A 25MHz crystal is used to generate all required clocks,
including the 50MHz RMII reference clock output for the
KSZ8081RNB.
The KSZ8081 provides diagnostic features to facilitate
system bring-up and debugging in production testing and
in product deployment. Parametric NAND tree support
enables fault detection between KSZ8081 I/Os and the
board. Micrel LinkMD® TDR-based cable diagnostics
identify faulty copper cabling.
• Auto-negotiation to automatically select the highest link-
up speed (10/100Mbps) and duplex (half/full)
• Power-down and power-saving modes
• LinkMD TDR-based cable diagnostics to identify faulty
copper cabling
• Parametric NAND Tree support for fault detection
The KSZ8081MNX and KSZ8081RNB are available in 32-
pin, lead-free QFN packages (see “Ordering Information”).
Datasheets and support documentation are available on
website at: www.micrel.com.
between chip I/Os and the board
• HBM ESD rating (6kV)
Functional Diagram
LinkMD is a registered trademark of Micrel, Inc.
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
Revision 1.4
August 19, 2015
Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Features (Continued)
Applications
• Game console
• IP phone
• IP set-top box
• IP TV
• LOM
• Printer
•
•
Loopback modes for diagnostics
Single 3.3V power supply with VDD I/O options for
1.8V, 2.5V, or 3.3V
•
•
Built-in 1.2V regulator for core
Available in 32-pin (5mm × 5mm) QFN package
Ordering Information
Temperature
Lead
Part Number
Package
Description
Range
Finish
Pb-Free
Pb-Free
KSZ8081MNXCA
KSZ8081MNXIA(1)
0°C to +70°C
−40°C to +85°C
32-Pin QFN
32-Pin QFN
MII, Commercial Temperature.
MII, Industrial Temperature.
RMII with 25MHz crystal/clock input and 50MHz
RMII REF_CLK output (power-up default),
Commercial Temperature.
KSZ8081RNBCA
KSZ8081RNBIA(1)
0°C to +70°C
32-Pin QFN
32-Pin QFN
Pb-Free
Pb-Free
RMII with 25MHz crystal/clock input and 50MHz
RMII REF_CLK output (power-up default),
Industrial Temperature.
−40°C to +85°C
KSZ8081MNX Evaluation Board
KSZ8081MNX-EVAL
KSZ8081RNB-EVAL
(Mounted with KSZ8081MNX device in commercial
temperature)
KSZ8081RNB Evaluation Board
(Mounted with KSZ8081RNB device in commercial
temperature)
Note:
1. Contact factory for lead time.
Revision 1.4
August 19, 2015
2
Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Revision History
Revision
Date
Summary of Changes
1.0
11/5/12
Initial release of datasheet.
Removed copper wire bonding part numbers from Ordering Information.
Added note for TXC (Pin 22) and Register 16h, Bit [15] regarding a Reserved Factory Mode for
KSZ8081MNX device.
1.1
2/6/14
Corrected TXC (Pin 22) pin type for KSZ8081MNX device.
Removed TXC and RXC clock connections for MII Back-to-Back mode. This is a datasheet correction.
There is no change to the silicon.
Added series resistance and load capacitance for the crystal selection criteria.
Added silver wire bonding part numbers to Ordering Information.
Updated Ordering Information to include Ordering Part Number and Device Marking.
Updated Table 7, add a note for Table 7.
1.2
1.3
12/18/14
Updated Table 8, updated NAND tree I/O testing descriptions.
Add Max frequency for MDC in MII Management (MIIM) Interface section.
Updated Table 23, add a note for Table 23.
04/14/15
Updated Figure 22 and Figure 22 descriptions.
Updated descriptions under Figure 23 for LED strap pins, add a note for Figure 23.
Fixed the missing value for maximum junction and thermal resistance (θJC).
Updated descriptions in local loopback section for data loopback path.
Updated Table 17 and Table 21.
Updated Ordering Information Table.
1.4
08/19/15
Updated pin 22 TXC and register 16h bit [15] description for MNX part.
Updated description and add an equation in LinkMD section.
Add HBM ESD rating in Features.
Revision 1.4
August 19, 2015
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Table of Contents
List of Figures.......................................................................................................................................................................... 6
List of Tables........................................................................................................................................................................... 7
Pin Configuration – KSZ8081MNX ......................................................................................................................................... 8
Pin Description – KSZ8081MNX............................................................................................................................................. 9
Strapping Options – KSZ8081MNX ......................................................................................................................................12
Pin Configuration – KSZ8081RNB........................................................................................................................................14
Pin Description – KSZ8081RNB ...........................................................................................................................................15
Strapping Options – KSZ8081RNB.......................................................................................................................................18
Functional Description: 10Base-T/100Base-TX Transceiver................................................................................................19
100Base-TX Transmit........................................................................................................................................................19
100Base-TX Receive.........................................................................................................................................................19
Scrambler/De-Scrambler (100Base-TX Only) ...................................................................................................................19
10Base-T Transmit............................................................................................................................................................19
10Base-T Receive .............................................................................................................................................................20
SQE and Jabber Function (10Base-T Only)......................................................................................................................20
PLL Clock Synthesizer ......................................................................................................................................................20
Auto-Negotiation................................................................................................................................................................20
MII Interface (KSZ8081MNX Only) .......................................................................................................................................22
MII Signal Definition...........................................................................................................................................................22
Transmit Clock (TXC)........................................................................................................................................................22
Transmit Enable (TXEN) ...................................................................................................................................................22
Transmit Data[3:0] (TXD[3:0]) ...........................................................................................................................................23
Receive Clock (RXC).........................................................................................................................................................23
Receive Data Valid (RXDV)...............................................................................................................................................23
Receive Data[3:0] (RXD[3:0])............................................................................................................................................23
Receive Error (RXER) .......................................................................................................................................................23
Carrier Sense (CRS) .........................................................................................................................................................23
Collision (COL) ..................................................................................................................................................................23
MII Signal Diagram ............................................................................................................................................................23
RMII Data Interface (KSZ8081RNB Only) ............................................................................................................................25
RMII – 25MHz Clock Mode................................................................................................................................................25
RMII – 50MHz Clock Mode................................................................................................................................................25
RMII Signal Definition........................................................................................................................................................25
Reference Clock (REF_CLK) ............................................................................................................................................25
Transmit Enable (TXEN) ...................................................................................................................................................26
Transmit Data[1:0] (TXD[1:0]) ...........................................................................................................................................26
Carrier Sense/Receive Data Valid (CRS_DV)...................................................................................................................26
Receive Data[1:0] (RXD[1:0])............................................................................................................................................26
Receive Error (RXER) .......................................................................................................................................................26
Collision Detection (COL)..................................................................................................................................................26
RMII Signal Diagram .........................................................................................................................................................26
Back-to-Back Mode – 100Mbps Copper Repeater ...............................................................................................................28
MII Back-to-Back Mode (KSZ8081MNX Only) ..................................................................................................................28
RMII Back-to-Back Mode (KSZ8081RNB Only)................................................................................................................29
MII Management (MIIM) Interface.........................................................................................................................................29
Interrupt (INTRP)...................................................................................................................................................................30
HP Auto MDI/MDI-X..............................................................................................................................................................30
Straight Cable....................................................................................................................................................................31
Crossover Cable................................................................................................................................................................31
Loopback Mode.....................................................................................................................................................................32
Local (Digital) Loopback....................................................................................................................................................32
Remote (Analog) Loopback...............................................................................................................................................33
LinkMD® Cable Diagnostic ....................................................................................................................................................34
Usage.............................................................................................................................................................................34
Revision 1.4
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
NAND Tree Support..............................................................................................................................................................35
NAND Tree I/O Testing .....................................................................................................................................................36
Power Management..............................................................................................................................................................37
Power-Saving Mode ..........................................................................................................................................................37
Energy-Detect Power-Down Mode....................................................................................................................................37
Power-Down Mode............................................................................................................................................................37
Slow-Oscillator Mode.........................................................................................................................................................37
Reference Circuit for Power and Ground Connections.........................................................................................................38
Typical Current/Power Consumption ....................................................................................................................................39
Transceiver (3.3V), Digital I/Os (3.3V) ..............................................................................................................................39
Transceiver (3.3V), Digital I/Os (2.5V) ..............................................................................................................................39
Transceiver (3.3V), Digital I/Os (1.8V) ..............................................................................................................................40
Register Map.........................................................................................................................................................................41
Register Description..............................................................................................................................................................42
Absolute Maximum Ratings ..................................................................................................................................................52
Operating Ratings .................................................................................................................................................................52
Electrical Characteristics.......................................................................................................................................................52
Timing Diagrams...................................................................................................................................................................54
MII SQE Timing (10Base-T) ..............................................................................................................................................54
MII Transmit Timing (10Base-T)........................................................................................................................................55
MII Receive Timing (10Base-T).........................................................................................................................................56
MII Transmit Timing (100Base-TX) ...................................................................................................................................57
MII Receive Timing (100Base-TX) ....................................................................................................................................58
RMII Timing .......................................................................................................................................................................59
Auto-Negotiation Timing....................................................................................................................................................60
MDC/MDIO Timing ............................................................................................................................................................61
Power-up/Reset Timing.....................................................................................................................................................62
Reset Circuit..........................................................................................................................................................................63
Reference Circuits – LED Strap-In Pins................................................................................................................................64
Reference Clock – Connection and Selection ......................................................................................................................65
Magnetic – Connection and Selection ..................................................................................................................................66
Package Information and Recommended Land Pattern.......................................................................................................68
Revision 1.4
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
List of Figures
Figure 1. Auto-Negotiation Flow Chart..................................................................................................................................21
Figure 2. KSZ8081MNX MII Interface...................................................................................................................................24
Figure 3. KSZ8081RNB RMII Interface (25MHz Clock Mode)..............................................................................................27
Figure 4. KSZ8081RNB RMII Interface (50MHz Clock Mode)..............................................................................................27
Figure 5. KSZ8081MNX/RNB to KSZ8081MNX/RNB Back-to-Back Copper Repeater .......................................................28
Figure 6. Typical Straight Cable Connection ........................................................................................................................31
Figure 7. Typical Crossover Cable Connection ....................................................................................................................31
Figure 8. Local (Digital) Loopback ........................................................................................................................................32
Figure 9. Remote (Analog) Loopback ...................................................................................................................................33
Figure 10. KSZ8081MNX/RNB Power and Ground Connections.........................................................................................38
Figure 11. MII SQE Timing (10Base-T) ................................................................................................................................54
Figure 12. MII Transmit Timing (10Base-T)..........................................................................................................................55
Figure 13. MII Receive Timing (10Base-T)...........................................................................................................................56
Figure 14. MII Transmit Timing (100Base-TX)......................................................................................................................57
Figure 15. MII Receive Timing (100Base-TX).......................................................................................................................58
Figure 16. RMII Timing – Data Received from RMII.............................................................................................................59
Figure 17. RMII Timing – Data Input to RMII ........................................................................................................................59
Figure 18. Auto-Negotiation Fast Link Pulse (FLP) Timing ..................................................................................................60
Figure 19. MDC/MDIO Timing...............................................................................................................................................61
Figure 20. Power-up/Reset Timing .......................................................................................................................................62
Figure 21. Recommended Reset Circuit...............................................................................................................................63
Figure 22. Recommended Reset Circuit for Interfacing with CPU/FPGA Reset Output ......................................................63
Figure 23. Reference Circuits for LED Strapping Pins .........................................................................................................64
Figure 24. 25MHz Crystal/Oscillator Reference Clock Connection ......................................................................................65
Figure 25. 50MHz Oscillator Reference Clock Connection ..................................................................................................65
Figure 26. Typical Magnetic Interface Circuit........................................................................................................................66
Revision 1.4
August 19, 2015
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
List of Tables
Table 1. MII Signal Definition ................................................................................................................................................22
Table 2. RMII Signal Defintion ..............................................................................................................................................25
Table 3. MII Signal Connection for MII Back-to-Back Mode (100Base-TX Copper Repeater).............................................28
Table 4. RMII Signal Connection for RMII Back-to-Back Mode (100Base-TX Copper Repeater) .......................................29
Table 5. MII Management Frame Format for the KSZ8081MNX/RNB .................................................................................30
Table 6. MDI/MDI-X Pin Definition ........................................................................................................................................30
Table 7. NAND Tree Test Pin Order for KSZ8081MNX........................................................................................................35
Table 8. NAND Tree Test Pin Order for KSZ8081RNB ........................................................................................................36
Table 9. KSZ8081MNX/RNB Power Pin Descriptions ..........................................................................................................38
Table 10. Typical Current/Power Consumption (VDDA_3.3 = 3.3V, VDDIO = 3.3V)...........................................................39
Table 11. Typical Current/Power Consumption (VDDA_3.3 = 3.3V, VDDIO = 2.5V)...........................................................39
Table 12. Typical Current/Power Consumption (VDDA_3.3 = 3.3V, VDDIO = 1.8V)...........................................................40
Table 13. MII SQE Timing (10Base-T) Parameters..............................................................................................................54
Table 14. MII Transmit Timing (10Base-T) Parameters........................................................................................................55
Table 15. MII Receive Timing (10Base-T) Parameters.........................................................................................................56
Table 16. MII Transmit Timing (100Base-TX) Parameters...................................................................................................57
Table 17. MII Receive Timing (100Base-TX) Parameters....................................................................................................58
Table 18. RMII Timing Parameters – KSZ8081RNB (25MHz input to XI pin, 50MHz output from REF_CLK pin) ..............59
Table 19. RMII Timing Parameters – KSZ8081RNB (50MHz input to XI pin) ......................................................................59
Table 20. Auto-Negotiation Fast Link Pulse (FLP) Timing Parameters................................................................................60
Table 21. MDC/MDIO Timing Parameters............................................................................................................................61
Table 22. Power-up/Reset Timing Parameters.....................................................................................................................62
Table 23. 25MHz Crystal/Reference Clock Selection Criteria ..............................................................................................65
Table 24. 50MHz Oscillator/Reference Clock Selection Criteria ..........................................................................................65
Table 25. Magnetics Selection Criteria .................................................................................................................................67
Table 26. Compatible Single-Port 10/100 Magnetics............................................................................................................67
Revision 1.4
August 19, 2015
7
Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Pin Configuration – KSZ8081MNX
32-Pin 5mm × 5mm QFN
Revision 1.4
August 19, 2015
8
Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Pin Description – KSZ8081MNX
Pin Number
Pin Name
Type(2)
Pin Function
1
GND
GND
Ground
1.2V core VDD (power supplied by KSZ8081MNX). Decouple with 2.2µF and 0.1µF
capacitors to ground.
2
VDD_1.2
P
3
4
5
6
7
VDDA_3.3
RXM
P
3.3V analog VDD.
I/O
I/O
I/O
I/O
Physical receive or transmit signal (− differential).
RXP
Physical receive or transmit signal (+ differential).
TXM
Physical transmit or receive signal (− differential).
TXP
Physical transmit or receive signal (+ differential).
Crystal feedback for 25MHz crystal.
8
XO
O
This pin is a no connect if an oscillator or external clock source is used.
Crystal / Oscillator / External Clock Input. 25MHz ±50ppm.
Set PHY transmit output current. Connect a 6.49kΩ resistor to ground on this pin.
9
XI
I
I
10
REXT
Management Interface (MII) Data I/O This pin has a weak pull-up, is open-drain, and
requires an external 1.0kΩ pull-up resistor.
11
12
MDIO
MDC
Ipu/Opu
Ipu
Management Interface (MII) Clock Input. This clock pin is synchronous to the MDIO
data pin.
MII Mode: MII Receive Data Output[3](3).
RXD3/
Config Mode: The pull-up/pull-down value is latched as PHYADDR[0] at the de-
assertion of reset.
13
14
15
Ipu/O
Ipd/O
Ipd/O
PHYAD0
See the Strapping Options – KSZ8081MNX section for details.
MII Mode: MII Receive Data Output[2](3).
RXD2/
Config Mode: The pull-up/pull-down value is latched as PHYADDR[1] at the de-
assertion of reset.
PHYAD1
See the Strapping Options – KSZ8081MNX section for details.
MII Mode: MII Receive Data Output[1](3).
RXD1/
Config Mode: The pull-up/pull-down value is latched as PHYADDR[2] at the de-
assertion of reset.
PHYAD2
See the Strapping Options – KSZ8081MNX section for details.
Notes:
2. P = Power supply.
GND = Ground.
I = Input.
O = Output.
I/O = Bi-directional.
Ipu = Input with internal pull-up (see Electrical Characteristics for value).
Ipu/O = Input with internal pull-up (see Electrical Characteristics for value) during power-up/reset; output pin otherwise.
Ipd/O = Input with internal pull-down (see Electrical Characteristics for value) during power-up/reset; output pin otherwise.
Ipu/Opu = Input with internal pull-up (see Electrical Characteristics for value) and output with internal pull-up (see Electrical Characteristics for
value).
3. MII RX Mode: The RXD[3:0] bits are synchronous with RXC. When RXDV is asserted, RXD[3:0] presents valid data to the MAC. RXD[3:0] is invalid
data from the PHY when RXDV is de-asserted.
Revision 1.4
August 19, 2015
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Pin Description – KSZ8081MNX (Continued)
Pin Number
Pin Name
Type(2)
Ipu/O
P
Pin Function
MII Mode: MII Receive Data Output[0](3).
RXD0/
Config Mode: The pull-up/pull-down value is latched as DUPLEX at the de-assertion
of reset.
16
17
18
DUPLEX
See the Strapping Options – KSZ8081MNX section for details.
3.3V, 2.5V, or 1.8V digital VDD
VDDIO
MII Mode: MII Receive Data Valid Output.
RXDV/
Config Mode: The pull-up/pull-down value is latched as CONFIG2 at the de-assertion
of reset.
Ipd/O
CONFIG2
See the Strapping Options – KSZ8081MNX section for details.
MII Mode: MII Receive Clock Output.
RXC/
Config Mode: The pull-up/pull-down value is latched as B-CAST_OFF at the de-
assertion of reset.
19
20
Ipd/O
Ipd/O
B-CAST_OFF
See the Strapping Options – KSZ8081MNX section for details.
MII mode: MII Receive Error Output.
RXER/
ISO
Config Mode: The pull-up/pull-down value is latched as ISOLATE at the de-assertion
of reset.
See the Strapping Options – KSZ8081MNX section for details.
Interrupt Output: Programmable Interrupt Output.
INTRP/
This pin has a weak pull-up, is open-drain, and requires an external 1.0kΩ pull-up
resistor.
21
22
Ipu/Opu
Ipd/O
Config Mode: The pull-up/pull-down value is latched as NAND Tree# at the de-
assertion of reset.
NAND_Tree#
TXC
See the Strapping Options – KSZ8081MNX section for details
MII Mode: MII Transmit Clock Output.
At the de-assertion of reset, this pin needs to latch in a pull-down value for normal
operation. If MAC side pulls this pin high, see Register 16h, Bit [15] for solution. It is
better having an external pull-down resistor to avoid MAC side pulls this pin high.
23
24
25
26
27
TXEN
TXD0
TXD1
TXD2
TXD3
I
I
I
I
I
MII Mode: MII Transmit Enable input.
MII Mode: MII Transmit Data Input[0](4).
MII Mode: MII Transmit Data Input[1](4).
MII Mode: MII Transmit Data Input[2](4).
MII Mode: MII Transmit Data Input[3](4).
MII Mode: MII Collision Detect output.
COL/
Config Mode: The pull-up/pull-down value is latched as CONFIG0 at the de-assertion
of reset.
28
29
Ipd/O
Ipd/O
CONFIG0
See the Strapping Options – KSZ8081MNX section for details.
MII mode: MII Carrier Sense output
CRS/
Config mode: The pull-up/pull-down value is latched as CONFIG1 at the de-assertion
of reset.
CONFIG1
See the Strapping Options – KSZ8081MNX section for details.
Note:
4. MII TX Mode: The TXD[3:0] bits are synchronous with TXC. When TXEN is asserted, TXD[3:0] presents valid data from the MAC. TXD[3:0] has no
effect on the PHY when TXEN is de-asserted.
Revision 1.4
August 19, 2015
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Pin Description – KSZ8081MNX (Continued)
Pin Number
Pin Name
Type(2)
Pin Function
LED Output: Programmable LED0 output.
Config Mode: Latched as auto-negotiation enable (Register 0h, Bit [12]) at the de-
assertion of reset.
See the Strapping Options – KSZ8081MNX section for details.
The LED0 pin is programmable using Register 1Fh bits [5:4], and is defined as
follows:
LED Mode = [00]
Link/Activity
No link
Pin State
High
LED Definition
OFF
LED0/
30
Ipu/O
NWAYEN
Link
Low
ON
Activity
Toggle
Blinking
LED Mode = [01]
Link
Pin State
High
LED Definition
No link
Link
OFF
ON
Low
LED Mode = [10], [11] Reserved
LED Output: Programmable LED1 Output.
Config Mode: Latched as Speed (Register 0h, Bit [13]) at the de-assertion of reset.
See the Strapping Options – KSZ8081MNX section for details.
The LED1 pin is programmable using Register 1Fh bits [5:4], and is defined as
follows:
LED Mode = [00]
Speed
Pin State
High
LED Definition
LED1/
10Base-T
100Base-TX
OFF
ON
31
Ipu/O
SPEED
Low
LED Mode = [01]
Activity
Pin State
High
LED Definition
OFF
No activity
Activity
Toggle
Blinking
LED Mode = [10], [11] Reserved
Chip Reset (active low).
Ground
32
RST#
GND
Ipu
PADDLE
GND
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Strapping Options – KSZ8081MNX
The strap-in pins are latched at the de-assertion of reset. In some systems, the MAC MII receive input pins may drive
high/low during power-up or reset, and consequently cause the PHY strap-in pins on the MII signals to be latched to
unintended high/low states. In this case, external pull-ups (4.7kΩ) or pull-downs (1.0kΩ) should be added on these PHY
strap-in pins to ensure that the intended values are strapped-in correctly.
Type(5)
Pin Number
Pin Name
Pin Function
PHYAD[2:0] is latched at de-assertion of reset and is configurable to any value from 0
to 7 with PHY Address 1 as the default value.
15
14
13
PHYAD2
PHYAD1
PHYAD0
Ipd/O
Ipd/O
Ipu/O
PHY Address 0 is assigned by default as the broadcast PHY address, but it can be
assigned as a unique PHY address after pulling the B-CAST_OFF strapping pin high
or writing a ‘1’ to Register 16h, Bit [9].
PHY Address bits [4:3] are set to 00 by default.
The CONFIG[2:0] strap-in pins are latched at the de-assertion of reset:
18
29
28
CONFIG2
CONFIG1
CONFIG0
Ipd/O
Ipd/O
Ipd/O
CONFIG[2:0]
000
Mode
MII (default)
110
MII back-to-back
Reserved – not used
001 – 101, 111
Isolate Mode:
Pull-up = Enable
20
31
16
ISO
Ipd/O
Ipu/O
Ipu/O
Pull-down (default) = Disable
At the de-assertion of reset, this pin value is latched into Register 0h, Bit [10].
Speed Mode:
Pull-up (default) = 100Mbps
Pull-down = 10Mbps
SPEED
DUPLEX
At the de-assertion of reset, this pin value is latched into Register 0h, Bit [13] as the
speed select, and also is latched into Register 4h (auto-negotiation advertisement) as
the speed capability support.
Duplex Mode:
Pull-up (default) = Half-duplex
Pull-down = Full-duplex
At the de-assertion of reset, this pin value is latched into Register 0h, Bit [8].
Note:
5. Ipu/O = Input with internal pull-up (see Electrical Characteristics for value) during power-up/reset; output pin otherwise.
Ipd/O = Input with internal pull-down (see Electrical Characteristics for value) during power-up/reset; output pin otherwise.
Ipu/Opu = Input with internal pull-up (see Electrical Characteristics for value) and output with internal pull-up (see Electrical Characteristics for
value).
Revision 1.4
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KSZ8081MNX/KSZ8081RNB
Strapping Options – KSZ8081MNX (Continued)
Type(5)
Pin Number
Pin Name
Pin Function
Nway Auto-Negotiation Enable:
Pull-up (default) = Enable auto-negotiation
Pull-down = Disable auto-negotiation
30
NWAYEN
Ipu/O
At the de-assertion of reset, this pin value is latched into Register 0h, Bit [12].
Broadcast Off – for PHY Address 0:
Pull-up = PHY Address 0 is set as an unique PHY address
Pull-down (default) = PHY Address 0 is set as a broadcast PHY address
At the de-assertion of reset, this pin value is latched by the chip.
NAND Tree Mode:
19
21
B-CAST_OFF
NAND_Tree#
Ipd/O
Pull-up (default) = Disable
Ipu/Opu
Pull-down = Enable
At the de-assertion of reset, this pin value is latched by the chip.
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KSZ8081MNX/KSZ8081RNB
Pin Configuration – KSZ8081RNB
32-Pin 5mm × 5mm QFN
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KSZ8081MNX/KSZ8081RNB
Pin Description – KSZ8081RNB
Pin Number
Pin Name
Type(6)
Pin Function
1
GND
GND
Ground
1.2V core VDD (power supplied by KSZ8081RNB). Decouple with 2.2µF and 0.1µF
capacitors to ground.
2
VDD_1.2
P
3
4
5
6
7
VDDA_3.3
RXM
P
3.3V analog VDD.
I/O
I/O
I/O
I/O
Physical receive or transmit signal (− differential).
Physical receive or transmit signal (+ differential).
Physical transmit or receive signal (− differential).
Physical transmit or receive signal (+ differential).
RXP
TXM
TXP
Crystal feedback for 25MHz crystal. This pin is a no connect if an oscillator or external
clock source is used.
8
9
XO
XI
O
I
25MHz Mode:
50MHz Mode:
25MHz ±50ppm Crystal / Oscillator / External Clock Input
50MHz ±50ppm Oscillator / External Clock Input
10
11
REXT
MDIO
I
Set PHY transmit output current. Connect a 6.49kΩ resistor to ground on this pin.
Management Interface (MII) Data I/O. This pin has a weak pull-up, is open-drain, and
requires an external 1.0kΩ pull-up resistor.
Ipu/Opu
Management Interface (MII) Clock Input. This clock pin is synchronous to the MDIO
data pin.
12
13
MDC
Ipu
The pull-up/pull-down value is latched as PHYADDR[0] at the de-assertion of reset.
See the Strapping Options – KSZ8081RNB section for details.
PHYAD0
Ipu/O
The pull-up/pull-down value is latched as PHYADDR[1] at the de-assertion of reset.
See the Strapping Options – KSZ8081RNB section for details.
RMII Mode: RMII Receive Data Output[1](7).
14
15
PHYAD1
Ipd/O
Ipd/O
RXD1/
Config Mode: The pull-up/pull-down value is latched as PHYADDR[2] at the de-
assertion of reset.
PHYAD2
See the Strapping Options – KSZ8081RNB section for details.
RMII Mode: RMII Receive Data Output[0](7).
RXD0/
Config Mode: The pull-up/pull-down value is latched as DUPLEX at the de-assertion
of reset.
16
Ipu/O
DUPLEX
See the Strapping Options – KSZ8081RNB section for details.
Notes:
6. P = Power supply.
GND = Ground.
I = Input.
O = Output.
I/O = Bi-directional.
Ipu = Input with internal pull-up (see Electrical Characteristics for value).
Ipu/O = Input with internal pull-up (see Electrical Characteristics for value) during power-up/reset; output pin otherwise.
Ipd/O = Input with internal pull-down (see Electrical Characteristics for value) during power-up/reset; output pin otherwise.
Ipu/Opu = Input with internal pull-up (see Electrical Characteristics for value) and output with internal pull-up (see Electrical Characteristics for
value).
NC = Pin is not bonded to the die.
7. RMII RX Mode: The RXD[1:0] bits are synchronous with the 50MHz RMII Reference Clock. For each clock period in which CRS_DV is asserted, two
bits of recovered data are sent by the PHY to the MAC.
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Pin Description – KSZ8081RNB (Continued)
Pin Number
Pin Name
Type(6)
Pin Function
17
VDDIO
P
3.3V, 2.5V, or 1.8V digital VDD.
RMII Mode: RMII Carrier Sense/Receive Data Valid Output.
CRS_DV/
CONFIG2
Config Mode: The pull-up/pull-down value is latched as CONFIG2 at the de-assertion
of reset.
18
19
20
21
Ipd/O
Ipd/O
See the Strapping Options – KSZ8081RNB section for details.
RMII Mode: 25MHz Mode. This pin provides the 50MHz RMII reference clock output
to the MAC. See also XI (Pin 9).
REF_CLK/
50MHz mode: This pin is a no connect. See also XI (Pin 9).
Config Mode: The pull-up/pull-down value is latched as B-CAST_OFF at the de-
assertion of reset.
B-CAST_OFF
See the Strapping Options – KSZ8081RNB section for details.
RMII Mode: RMII Receive Error Output.
RXER/
ISO
Config Mode: The pull-up/pull-down value is latched as ISOLATE at the de-assertion
of reset.
Ipd/O
See the Strapping Options – KSZ8081RNB section for details.
Interrupt Output: Programmable Interrupt Output.
INTRP/
This pin has a weak pull-up, is open-drain, and requires an external 1.0kΩ pull-up
resistor.
Ipu/Opu
Config Mode: The pull-up/pull-down value is latched as NAND Tree# at the de-
assertion of reset.
NAND_Tree#
See the Strapping Options – KSZ8081RNB section for details.
No Connect. This pin is not bonded and can be left floating.
RMII Transmit Enable input.
RMII Transmit Data Input[0](8).
RMII Transmit Data Input[1](8).
22
23
24
25
26
27
NC
TXEN
TXD0
TXD1
NC
-
I
I
I
-
-
No Connect. This pin is not bonded and can be left floating.
No Connect. This pin is not bonded and can be left floating.
NC
The pull-up/pull-down value is latched as CONFIG0 at the de-assertion of reset. See
the Strapping Options – KSZ8081RNB section for details.
28
29
CONFIG0
CONFIG1
Ipd/O
Ipd/O
The pull-up/pull-down value is latched as CONFIG1 at the de-assertion of reset. See
the Strapping Options – KSZ8081RNB section for details.
Note:
8. RMII TX Mode: The TXD[1:0] bits are synchronous with the 50MHz RMII Reference Clock. For each clock period in which TXEN is asserted, two bits
of data are received by the PHY from the MAC.
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Pin Description – KSZ8081RNB (Continued)
Pin Number
Pin Name
Type(6)
Pin Function
LED Output: Programmable LED0 Output.
Config Mode: Latched as auto-negotiation enable (Register 0h, Bit [12]) at the de-
assertion of reset.
See the Strapping Options – KSZ8081RNB section for details.
The LED0 pin is programmable using Register 1Fh bits [5:4], and is defined as
follows:
LED Mode = [00]
Link/Activity
No link
Pin State
High
LED Definition
OFF
LED0/
30
Ipu/O
NWAYEN
Link
Low
ON
Activity
Toggle
Blinking
LED Mode = [01]
Link
Pin State
High
LED Definition
No link
Link
OFF
ON
Low
LED Mode = [10], [11] Reserved
LED Output: Programmable LED1 Output.
Config Mode: Latched as Speed (Register 0h, Bit [13]) at the de-assertion of reset.
See the Strapping Options – KSZ8081RNB section for details.
The LED1 pin is programmable using Register 1Fh bits [5:4], and is defined as
follows:
LED Mode = [00]
Speed
Pin State
High
LED Definition
LED1/
10Base-T
100Base-TX
OFF
ON
31
Ipu/O
SPEED
Low
LED Mode = [01]
Activity
Pin State
High
LED Definition
OFF
No activity
Activity
Toggle
Blinking
LED Mode = [10], [11] Reserved
Chip Reset (active low).
Ground.
32
RST#
GND
Ipu
PADDLE
GND
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Strapping Options – KSZ8081RNB
The strap-in pins are latched at the de-assertion of reset. In some systems, the MAC RMII receive input pins may drive
high/low during power-up or reset, and consequently cause the PHY strap-in pins on the RMII signals to be latched to
unintended high/low states. In this case, external pull-ups (4.7kΩ) or pull-downs (1.0kΩ) should be added on these PHY
strap-in pins to ensure that the intended values are strapped-in correctly.
Type(9)
Pin Number
Pin Name
Pin Function
PHYAD[2:0] is latched at de-assertion of reset and is configurable to any value from 0
to 7 with PHY Address 1 as the default value.
15
14
13
PHYAD2
PHYAD1
PHYAD0
Ipd/O
Ipd/O
Ipu/O
PHY Address 0 is assigned by default as the broadcast PHY address, but it can be
assigned as a unique PHY address after pulling the B-CAST_OFF strapping pin high
or writing a ‘1’ to Register 16h, Bit [9].
PHY Address bits [4:3] are set to 00 by default.
The CONFIG[2:0] strap-in pins are latched at the de-assertion of reset.
CONFIG[2:0]
Mode
18
29
28
CONFIG2
CONFIG1
CONFIG0
Ipd/O
Ipd/O
Ipd/O
001
RMII
101
RMII back-to-back
Reserved – not used
000, 010 – 100, 110, 111
Isolate mode
Pull-up = Enable
Pull-down (default) = Disable
20
31
ISO
Ipd/O
Ipu/O
At the de-assertion of reset, this pin value is latched into Register 0h, Bit [10].
Speed mode
Pull-up (default) = 100Mbps
Pull-down = 10Mbps
SPEED
At the de-assertion of reset, this pin value is latched into Register 0h, Bit [13] as the
speed select, and also is latched into Register 4h (auto-negotiation advertisement) as
the speed capability support.
Duplex mode
Pull-up (default) = Half-duplex
Pull-down = Full-duplex
16
30
19
21
DUPLEX
NWAYEN
Ipu/O
Ipu/O
At the de-assertion of reset, this pin value is latched into Register 0h, Bit [8].
Nway auto-negotiation enable
Pull-up (default) = Enable auto-negotiation
Pull-down = Disable auto-negotiation
At the de-assertion of reset, this pin value is latched into Register 0h, Bit [12].
Broadcast off – for PHY Address 0
Pull-up = PHY Address 0 is set as an unique PHY address
Pull-down (default) = PHY Address 0 is set as a broadcast PHY address
B-CAST_OFF
NAND_Tree#
Ipd/O
At the de-assertion of reset, this pin value is latched by the chip.
NAND tree mode
Pull-up (default) = Disable
Pull-down = Enable
Ipu/Opu
At the de-assertion of reset, this pin value is latched by the chip.
Note:
9. Ipu/O = Input with internal pull-up (see Electrical Characteristics for value) during power-up/reset; output pin otherwise.
Ipd/O = Input with internal pull-down (see Electrical Characteristics for value) during power-up/reset; output pin otherwise.
Ipu/Opu = Input with internal pull-up (see Electrical Characteristics for value) and output with internal pull-up (see Electrical Characteristics for
value).
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KSZ8081MNX/KSZ8081RNB
Functional Description: 10Base-T/100Base-TX Transceiver
The KSZ8081 is an integrated single 3.3V supply Fast Ethernet transceiver. It is fully compliant with the IEEE 802.3
Specification, and reduces board cost and simplifies board layout by using on-chip termination resistors for the two
differential pairs and by integrating the regulator to supply the 1.2V core.
On the copper media side, the KSZ8081 supports 10Base-T and 100Base-TX for transmission and reception of data over
a standard CAT-5 unshielded twisted pair (UTP) cable, and HP Auto MDI/MDI-X for reliable detection of and correction for
straight-through and crossover cables.
On the MAC processor side, the KSZ8081MNX offers the Media Independent Interface (MII) and the KSZ8081RNB offers
the Reduced Media Independent Interface (RMII) for direct connection with MII and RMII compliant Ethernet MAC
processors and switches, respectively.
The MII management bus option gives the MAC processor complete access to the KSZ8081 control and status registers.
Additionally, an interrupt pin eliminates the need for the processor to poll for PHY status change.
The KSZ8081MNX/RNB is used to refer to both KSZ8081MNX and KSZ8081RNB versions in this datasheet.
100Base-TX Transmit
The 100Base-TX transmit function performs parallel-to-serial conversion, 4B/5B encoding, scrambling, NRZ-to-NRZI
conversion, and MLT3 encoding and transmission.
The circuitry starts with a parallel-to-serial conversion, which converts the MII data from the MAC into a 125MHz serial bit
stream. The data and control stream is then converted into 4B/5B coding and followed by a scrambler. The serialized data
is further converted from NRZ-to-NRZI format, and then transmitted in MLT3 current output. The output current is set by
an external 6.49kΩ 1% resistor for the 1:1 transformer ratio.
The output signal has a typical rise/fall time of 4ns and complies with the ANSI TP-PMD standard regarding amplitude
balance, overshoot, and timing jitter. The wave-shaped 10Base-T output is also incorporated into the 100Base-TX
transmitter.
100Base-TX Receive
The 100Base-TX receiver function performs adaptive equalization, DC restoration, MLT3-to-NRZI conversion, data and
clock recovery, NRZI-to-NRZ conversion, de-scrambling, 4B/5B decoding, and serial-to-parallel conversion.
The receiving side starts with the equalization filter to compensate for inter-symbol interference (ISI) over the twisted pair
cable. Because the amplitude loss and phase distortion is a function of the cable length, the equalizer must adjust its
characteristics to optimize performance. In this design, the variable equalizer makes an initial estimation based on
comparisons of incoming signal strength against some known cable characteristics, then tunes itself for optimization. This
is an ongoing process and self-adjusts against environmental changes such as temperature variations.
Next, the equalized signal goes through a DC-restoration and data-conversion block. The DC-restoration circuit
compensates for the effect of baseline wander and improves the dynamic range. The differential data-conversion circuit
converts MLT3 format back to NRZI. The slicing threshold is also adaptive.
The clock-recovery circuit extracts the 125MHz clock from the edges of the NRZI signal. This recovered clock is then used
to convert the NRZI signal to NRZ format. This signal is sent through the de-scrambler, then the 4B/5B decoder. Finally,
the NRZ serial data is converted to MII format and provided as the input data to the MAC.
Scrambler/De-Scrambler (100Base-TX Only)
The scrambler spreads the power spectrum of the transmitted signal to reduce electromagnetic interference (EMI) and
baseline wander. The de-scrambler recovers the scrambled signal.
10Base-T Transmit
The 10Base-T drivers are incorporated with the 100Base-TX drivers to allow for transmission using the same magnetic.
The drivers perform internal wave-shaping and pre-emphasis, and output 10Base-T signals with a typical amplitude of
2.5V peak. The 10Base-T signals have harmonic contents that are at least 27dB below the fundamental frequency when
driven by an all-ones Manchester-encoded signal.
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10Base-T Receive
On the receive side, input buffer and level detecting squelch circuits are used. A differential input receiver circuit and a
phase-locked loop (PLL) performs the decoding function. The Manchester-encoded data stream is separated into clock
signal and NRZ data. A squelch circuit rejects signals with levels less than 400mV, or with short pulse widths, to prevent
noise at the RXP and RXM inputs from falsely triggering the decoder. When the input exceeds the squelch limit, the PLL
locks onto the incoming signal and the KSZ8081MNX/RNB decodes a data frame. The receive clock is kept active during
idle periods between data receptions.
SQE and Jabber Function (10Base-T Only)
In 10Base-T operation, a short pulse is put out on the COL pin after each frame is transmitted. This SQE test is needed to
test the 10Base-T transmit/receive path. If transmit enable (TXEN) is high for more than 20ms (jabbering), the 10Base-T
transmitter is disabled and COL is asserted high. If TXEN is then driven low for more than 250ms, the 10Base-T
transmitter is re-enabled and COL is de-asserted (returns to low).
PLL Clock Synthesizer
The KSZ8081MNX/RNB generates all internal clocks and all external clocks for system timing from an external 25MHz
crystal, oscillator, or reference clock. For the KSZ8081RNB in RMII 50MHz clock mode, these clocks are generated from
an external 50MHz oscillator or system clock.
Auto-Negotiation
The KSZ8081MNX/RNB conforms to the auto-negotiation protocol, defined in Clause 28 of the IEEE 802.3 Specification.
Auto-negotiation allows unshielded twisted pair (UTP) link partners to select the highest common mode of operation.
During auto-negotiation, link partners advertise capabilities across the UTP link to each other and then compare their own
capabilities with those they received from their link partners. The highest speed and duplex setting that is common to the
two link partners is selected as the mode of operation.
The following list shows the speed and duplex operation mode from highest to lowest priority.
• Priority 1: 100Base-TX, full-duplex
• Priority 2: 100Base-TX, half-duplex
• Priority 3: 10Base-T, full-duplex
• Priority 4: 10Base-T, half-duplex
If auto-negotiation is not supported or the KSZ8081MNX/RNB link partner is forced to bypass auto-negotiation, then the
KSZ8081MNX/RNB sets its operating mode by observing the signal at its receiver. This is known as parallel detection,
which allows the KSZ8081MNX/RNB to establish a link by listening for a fixed signal protocol in the absence of the auto-
negotiation advertisement protocol.
Auto-negotiation is enabled by either hardware pin strapping (NWAYEN, Pin 42) or software (Register 0h, Bit [12]).
By default, auto-negotiation is enabled after power-up or hardware reset. After that, auto-negotiation can be enabled or
disabled by Register 0h, Bit [12]. If auto-negotiation is disabled, the speed is set by Register 0h, Bit [13], and the duplex is
set by Register 0h, Bit [8].
The auto-negotiation link-up process is shown in Figure 1.
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Figure 1. Auto-Negotiation Flow Chart
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MII Interface (KSZ8081MNX Only)
The Media Independent Interface (MII) is compliant with the IEEE 802.3 Specification. It provides a common interface
between MII PHYs and MACs, and has the following key characteristics:
• Pin count is 15 pins (6 pins for data transmission, 7 pins for data reception, and 2 pins for carrier and collision
indication).
• 10Mbps and 100Mbps data rates are supported at both half- and full-duplex.
• Data transmission and reception are independent and belong to separate signal groups.
• Transmit data and receive data are each 4 bits wide, a nibble.
By default, the KSZ8081MNX is configured to MII mode after it is powered up or hardware reset with the following:
• A 25MHz crystal connected to XI, XO (pins 9, 8), or an external 25MHz clock source (oscillator) connected to XI.
• The CONFIG[2:0] strapping pins (pins 18, 29, 28) set to 000 (default setting).
MII Signal Definition
Table 1 describes the MII signals. Refer to Clause 22 of the IEEE 802.3 Specification for detailed information.
Table 1. MII Signal Definition
Direction
Direction
MII Signal Name
(with respect to PHY,
KSZ8081MNX signal)
Description
(with respect to MAC)
Transmit Clock
TXC
Output
Input
(2.5MHz for 10Mbps; 25MHz for 100Mbps)
Transmit Enable
TXEN
Input
Input
Output
Output
TXD[3:0]
Transmit Data[3:0]
Receive Clock
RXC
Output
Input
(2.5MHz for 10Mbps; 25MHz for 100Mbps)
Receive Data Valid
RXDV
RXD[3:0]
RXER
CRS
Output
Output
Output
Output
Output
Input
Input
Receive Data[3:0]
Input, or (not required) Receive Error
Input
Input
Carrier Sense
COL
Collision Detection
Transmit Clock (TXC)
TXC is sourced by the PHY. It is a continuous clock that provides the timing reference for TXEN and TXD[3:0]. TXC is
2.5MHz for 10Mbps operation and 25MHz for 100Mbps operation.
Transmit Enable (TXEN)
TXEN indicates that the MAC is presenting nibbles on TXD[3:0] for transmission. It is asserted synchronously with the first
nibble of the preamble and remains asserted while all nibbles to be transmitted are presented on the MII. It is negated
before the first TXC following the final nibble of a frame.
TXEN transitions synchronously with respect to TXC.
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Transmit Data[3:0] (TXD[3:0])
TXD[3:0] transitions synchronously with respect to TXC. When TXEN is asserted, TXD[3:0] are accepted by the PHY for
transmission. TXD[3:0] is 00 to indicate idle when TXEN is de-asserted. Values other than 00 on TXD[3:0] while TXEN is
de-asserted are ignored by the PHY.
Receive Clock (RXC)
RXC provides the timing reference for RXDV, RXD[3:0], and RXER.
• In 10Mbps mode, RXC is recovered from the line while the carrier is active. RXC is derived from the PHY’s reference
clock when the line is idle or the link is down.
• In 100Mbps mode, RXC is continuously recovered from the line. If the link is down, RXC is derived from the PHY’s
reference clock.
RXC is 2.5MHz for 10Mbps operation and 25MHz for 100Mbps operation.
Receive Data Valid (RXDV)
RXDV is driven by the PHY to indicate that the PHY is presenting recovered and decoded nibbles on RXD[3:0].
• In 10Mbps mode, RXDV is asserted with the first nibble of the start-of-frame delimiter (SFD), 5D, and remains asserted
until the end of the frame.
• In 100Mbps mode, RXDV is asserted from the first nibble of the preamble to the last nibble of the frame.
RXDV transitions synchronously with respect to RXC.
Receive Data[3:0] (RXD[3:0])
RXD[3:0] transitions synchronously with respect to RXC. For each clock period in which RXDV is asserted, RXD[3:0]
transfers a nibble of recovered data from the PHY.
Receive Error (RXER)
RXER is asserted for one or more RXC periods to indicate that a symbol error (for example, a coding error that a PHY can
detect that may otherwise be undetectable by the MAC sub-layer) was detected somewhere in the frame being
transferred from the PHY.
RXER transitions synchronously with respect to RXC. While RXDV is de-asserted, RXER has no effect on the MAC.
Carrier Sense (CRS)
CRS is asserted and de-asserted as follows:
• In 10Mbps mode, CRS assertion is based on the reception of valid preambles. CRS de-assertion is based on the
reception of an end-of-frame (EOF) marker.
• In 100Mbps mode, CRS is asserted when a start-of-stream delimiter or /J/K symbol pair is detected. CRS is de-
asserted when an end-of-stream delimiter or /T/R symbol pair is detected. Additionally, the PMA layer de-asserts CRS if
IDLE symbols are received without /T/R.
Collision (COL)
COL is asserted in half-duplex mode whenever the transmitter and receiver are simultaneously active on the line. This
informs the MAC that a collision has occurred during its transmission to the PHY. COL transitions asynchronously with
respect to TXC and RXC.
MII Signal Diagram
The KSZ8081MNX MII pin connections to the MAC are shown in Figure 2.
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Figure 2. KSZ8081MNX MII Interface
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RMII Data Interface (KSZ8081RNB Only)
The Reduced Media Independent Interface (RMII) specifies a low pin count Media Independent Interface (MII). It provides
a common interface between physical layer and MAC layer devices, and has the following key characteristics:
• Pin count is 8 pins (3 pins for data transmission, 4 pins for data reception, and 1 pin for the 50MHz reference clock).
• 10Mbps and 100Mbps data rates are supported at both half- and full-duplex.
• Data transmission and reception are independent and belong to separate signal groups.
• Transmit data and receive data are each 2 bits wide, a dibit.
RMII – 25MHz Clock Mode
The KSZ8081RNB is configured to RMII – 25MHz clock mode after it is powered up or hardware reset with the following:
• A 25MHz crystal connected to XI, XO (pins 9, 8), or an external 25MHz clock source (oscillator) connected to XI.
• The CONFIG[2:0] strapping pins (pins 18, 29, 28) set to 001.
• Register 1Fh, Bit [7] is set to 0 (default value) to select 25MHz clock mode.
RMII – 50MHz Clock Mode
The KSZ8081RNB is configured to RMII – 50MHz clock mode after it is powered up or hardware reset with the following:
• An external 50MHz clock source (oscillator) connected to XI (Pin 9).
• The CONFIG[2:0] strapping pins (pins 18, 29, 28) set to 001.
• Register 1Fh, Bit [7] is set to 1 to select 50MHz clock mode.
RMII Signal Definition
Table 2 describes the RMII signals. Refer to RMII Specification v1.2 for detailed information.
Table 2. RMII Signal Defintion
Direction
Direction
RMII Signal Name
(with respect to PHY,
KSZ8081RNB signal)
Description
(with respect to MAC)
REF_CLK
Output (25MHz clock mode) /
Input/
Synchronous 50MHz reference clock for
receive, transmit, and control interface
<no connect> (50MHz clock mode) Input or <no connect>
TXEN
Input
Input
Output
Output
Input
Transmit Enable
TXD[1:0]
CRS_DV
RXD[1:0]
RXER
Transmit Data[1:0]
Output
Output
Output
Carrier Sense/Receive Data Valid
Receive Data[1:0]
Input
Input, or (not required) Receive Error
Reference Clock (REF_CLK)
REF_CLK is a continuous 50MHz clock that provides the timing reference for TXEN, TXD[1:0], CRS_DV, RXD[1:0], and
RX_ER.
For 25MHz clock mode, the KSZ8081RNB generates and outputs the 50MHz RMII REF_CLK to the MAC at REF_CLK
(Pin 19).
For 50MHz clock mode, the KSZ8081RNB takes in the 50MHz RMII REF_CLK from the MAC or system board at XI (Pin
9) and leaves the REF_CLK (Pin 19) as a no connect.
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Transmit Enable (TXEN)
TXEN indicates that the MAC is presenting dibits on TXD[1:0] for transmission. It is asserted synchronously with the first
dibit of the preamble and remains asserted while all dibits to be transmitted are presented on the RMII. It is negated
before the first REF_CLK following the final dibit of a frame.
TXEN transitions synchronously with respect to REF_CLK.
Transmit Data[1:0] (TXD[1:0])
TXD[1:0] transitions synchronously with respect to REF_CLK. When TXEN is asserted, the PHY accepts TXD[1:0] for
transmission.
TXD[1:0] is 00 to indicate idle when TXEN is de-asserted. The PHY ignores values other than 00 on TXD[1:0] while TXEN
is de-asserted.
Carrier Sense/Receive Data Valid (CRS_DV)
The PHY asserts CRS_DV when the receive medium is non-idle. It is asserted asynchronously when a carrier is detected.
This happens when squelch is passed in 10Mbps mode, and when two non-contiguous 0s in 10 bits are detected in
100Mbps mode. Loss of carrier results in the de-assertion of CRS_DV.
While carrier detection criteria are met, CRS_DV remains asserted continuously from the first recovered dibit of the frame
through the final recovered dibit. It is negated before the first REF_CLK that follows the final dibit. The data on RXD[1:0] is
considered valid after CRS_DV is asserted. However, because the assertion of CRS_DV is asynchronous relative to
REF_CLK, the data on RXD[1:0] is 00 until receive signals are properly decoded.
Receive Data[1:0] (RXD[1:0])
RXD[1:0] transitions synchronously with respect to REF_CLK. For each clock period in which CRS_DV is asserted,
RXD[1:0] transfers two bits of recovered data from the PHY.
RXD[1:0] is 00 to indicate idle when CRS_DV is de-asserted. The MAC ignores values other than 00 on RXD[1:0] while
CRS_DV is de-asserted.
Receive Error (RXER)
RXER is asserted for one or more REF_CLK periods to indicate that a symbol error (for example, a coding error that a
PHY can detect that may otherwise be undetectable by the MAC sub-layer) was detected somewhere in the frame being
transferred from the PHY.
RXER transitions synchronously with respect to REF_CLK. . While CRS_DV is de-asserted, RXER has no effect on the
MAC.
Collision Detection (COL)
The MAC regenerates the COL signal of the MII from TXEN and CRS_DV.
RMII Signal Diagram
The KSZ8081RNB RMII pin connections to the MAC for 25MHz clock mode are shown in Figure 3. The connections for
50MHz clock mode are shown in Figure 4.
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Figure 3. KSZ8081RNB RMII Interface (25MHz Clock Mode)
Figure 4. KSZ8081RNB RMII Interface (50MHz Clock Mode)
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Back-to-Back Mode – 100Mbps Copper Repeater
Two KSZ8081MNX/RNB devices can be connected back-to-back to form a 100Base-TX copper repeater.
Figure 5. KSZ8081MNX/RNB to KSZ8081MNX/RNB Back-to-Back Copper Repeater
MII Back-to-Back Mode (KSZ8081MNX Only)
In MII back-to-back mode, a KSZ8081MNX interfaces with another KSZ8081MNX to provide a complete 100Mbps copper
repeater solution.
The KSZ8081MNX devices are configured to MII back-to-back mode after power-up or reset with the following:
• Strapping pin CONFIG[2:0] (Pins 18, 29, 28) set to 110
• A common 25MHz reference clock connected to XI (Pin 9) of both KSZ8081MNX devices
• MII signals connected as shown in Table 3.
Table 3. MII Signal Connection for MII Back-to-Back Mode (100Base-TX Copper Repeater)
KSZ8081MNX (100Base-TX copper)
[Device 1]
KSZ8081MNX (100Base-TX copper)
[Device 2]
Pin Name
Pin Number
Pin Type
Pin Name
Pin Number
Pin Type
RXDV
RXD3
RXD2
RXD1
RXD0
TXEN
TXD3
TXD2
TXD1
TXD0
18
13
14
15
16
23
27
26
25
24
Output
Output
Output
Output
Output
Input
TXEN
TXD3
TXD2
TXD1
TXD0
RXDV
RXD3
RXD2
RXD1
RXD0
23
27
26
25
24
18
13
14
15
16
Input
Input
Input
Input
Input
Output
Output
Output
Output
Output
Input
Input
Input
Input
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RMII Back-to-Back Mode (KSZ8081RNB Only)
In RMII back-to-back mode, a KSZ8081RNB interfaces with another KSZ8081RNB to provide a complete 100Mbps
copper repeater solution.
The KSZ8081RNB devices are configured to RMII back-to-back mode after power-up or reset with the following:
• Strapping pin CONFIG[2:0] (Pins 18, 29, 28) set to 101
• A common 50MHz reference clock connected to XI (Pin 9) of both KSZ8081RNB devices
• RMII signals connected as shown in Table 4.
Table 4. RMII Signal Connection for RMII Back-to-Back Mode (100Base-TX Copper Repeater)
KSZ8081RNB (100Base-TX copper)
[Device 1]
KSZ8081RNB (100Base-TX copper)
[Device 2]
Pin Name
Pin Number
Pin Type
Pin Name
Pin Number
Pin Type
Input
CRSDV
RXD1
RXD0
TXEN
TXD1
TXD0
18
15
16
23
25
24
Output
Output
Output
Input
TXEN
TXD1
23
25
24
18
15
16
Input
TXD0
Input
CRSDV
RXD1
RXD0
Output
Output
Output
Input
Input
MII Management (MIIM) Interface
The KSZ8081MNX/RNB supports the IEEE 802.3 MII management interface, also known as the Management Data
Input/Output (MDIO) interface. This interface allows an upper-layer device, such as a MAC processor, to monitor and
control the state of the KSZ8081MNX/RNB. An external device with MIIM capability is used to read the PHY status and/or
configure the PHY settings. More details about the MIIM interface can be found in Clause 22.2.4 of the IEEE 802.3
Specification.
The MIIM interface consists of the following:
• A physical connection that incorporates the clock line (MDC) and the data line (MDIO).
• A specific protocol that operates across the physical connection mentioned earlier, which allows the external controller
to communicate with one or more PHY devices.
• A set of 16-bit MDIO registers. Registers [0:8] are standard registers, and their functions are defined in the IEEE 802.3
Specification. The additional registers are provided for expanded functionality. See the “Register Map” section for
details.
As the default, the KSZ8081MNX/RNB supports unique PHY addresses 1 to 7, and broadcast PHY address 0. The latter
is defined in the IEEE 802.3 Specification, and can be used to read/write to a single KSZ8081MNX/RNB device, or write
to multiple KSZ8081MNX/RNB devices simultaneously.
PHY address 0 can optionally be disabled as the broadcast address by either hardware pin strapping (B-CAST_OFF, Pin
19) or software (Register 16h, Bit [9]), and assigned as a unique PHY address.
The PHYAD[2:0] strapping pins are used to assign a unique PHY address between 0 and 7 to each KSZ8081MNX/RNB
device.
The MIIM interface can operates up to a maximum clock speed of 10MHz MAC clock.
Table 5 shows the MII management frame format for the KSZ8081MNX/RNB.
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Table 5. MII Management Frame Format for the KSZ8081MNX/RNB
Start of Read/Write PHY Address
Preamble
REG Address
Bits [4:0]
Data
Bits [15:0]
TA
Idle
Frame
01
OP Code
Bits [4:0]
00AAA
Read
Write
32 1’s
32 1’s
10
01
RRRRR
RRRRR
Z0
10
DDDDDDDD_DDDDDDDD
DDDDDDDD_DDDDDDDD
Z
Z
01
00AAA
Interrupt (INTRP)
INTRP (Pin 21) is an optional interrupt signal that is used to inform the external controller that there has been a status
update to the KSZ8081MNX/RNB PHY register. Bits [15:8] of Register 1Bh are the interrupt control bits to enable and
disable the conditions for asserting the INTRP signal. Bits [7:0] of Register 1Bh are the interrupt status bits to indicate
which interrupt conditions have occurred. The interrupt status bits are cleared after reading Register 1Bh.
Bit [9] of Register 1Fh sets the interrupt level to active high or active low. The default is active low.
The MII management bus option gives the MAC processor complete access to the KSZ8081MNX/RNB control and status
registers. Additionally, an interrupt pin eliminates the need for the processor to poll the PHY for status change.
HP Auto MDI/MDI-X
HP Auto MDI/MDI-X configuration eliminates the need to decide whether to use a straight cable or a crossover cable
between the KSZ8081MNX/RNB and its link partner. This feature allows the KSZ8081MNX/RNB to use either type of
cable to connect with a link partner that is in either MDI or MDI-X mode. The auto-sense function detects transmit and
receive pairs from the link partner and assigns transmit and receive pairs to the KSZ8081MNX/RNB accordingly.
HP Auto MDI/MDI-X is enabled by default. It is disabled by writing a ‘1’ to Register 1Fh, Bit [13]. MDI and MDI-X mode is
selected by Register 1Fh, Bit [14] if HP Auto MDI/MDI-X is disabled.
An isolation transformer with symmetrical transmit and receive data paths is recommended to support Auto MDI/MDI-X.
Table 6 shows how the IEEE 802.3 Standard defines MDI and MDI-X.
Table 6. MDI/MDI-X Pin Definition
MDI
MDI-X
RJ-45 Pin
Signal
TX+
RJ-45 Pin
Signal
RX+
RX−
TX+
1
2
3
6
1
2
3
6
TX−
RX+
RX−
TX−
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Straight Cable
A straight cable connects an MDI device to an MDI-X device, or an MDI-X device to an MDI device. Figure 6 shows a
typical straight cable connection between a NIC card (MDI device) and a switch or hub (MDI-X device).
Figure 6. Typical Straight Cable Connection
Crossover Cable
A crossover cable connects an MDI device to another MDI device, or an MDI-X device to another MDI-X device. Figure 7
shows a typical crossover cable connection between two switches or hubs (two MDI-X devices).
Figure 7. Typical Crossover Cable Connection
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Loopback Mode
The KSZ8081MNX/RNB supports the following loopback operations to verify analog and/or digital data paths.
• Local (digital) loopback
• Remote (analog) loopback
Local (Digital) Loopback
This loopback mode checks the MII/RMII transmit and receive data paths between the KSZ8081MNX/RNB and the
external MAC, and is supported for both speeds (10/100Mbps) at full-duplex.
The loopback data path is shown in Figure 8.
1. The MII/RMII MAC transmits frames to the KSZ8081MNX/RNB.
2. Frames are wrapped around inside the KSZ8081MNX/RNB.
3. The KSZ8081MNX/RNB transmits frames back to the MII/RMII MAC.
4. Except the frames back to the RMII MAC, the transmit frames also go out from the copper port.
Figure 8. Local (Digital) Loopback
The following programming action and register settings are used for local loopback mode.
For 10/100Mbps loopback,
• Set Register 0h,
Bit [14] = 1
Bit [13] = 0/1
Bit [12] = 0
Bit [8] = 1
// Enable local loopback mode
// Select 10Mbps/100Mbps speed
// Disable auto-negotiation
// Select full-duplex mode
If don’t want the frames go out from the copper port in the local loopback, please follow the steps as below.
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.
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Remote (Analog) Loopback
This loopback mode checks the line (differential pairs, transformer, RJ-45 connector, Ethernet cable) transmit and receive
data paths between the KSZ8081MNX/RNB and its link partner, and is supported for 100Base-TX full-duplex mode only.
The loopback data path is shown in Figure 9.
1. The Fast Ethernet (100Base-TX) PHY link partner transmits frames to the KSZ8081MNX/RNB.
2. Frames are wrapped around inside the KSZ8081MNX/RNB.
3. The KSZ8081MNX/RNB transmits frames back to the Fast Ethernet (100Base-TX) PHY link partner.
Figure 9. Remote (Analog) Loopback
The following programming steps and register settings are used for remote loopback mode.
1. Set Register 0h,
Bits [13] = 1
Bit [12] = 0
Bit [8] = 1
// Select 100Mbps speed
// Disable auto-negotiation
// 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
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LinkMD® Cable Diagnostic
The LinkMD function uses time-domain reflectometry (TDR) to analyze the cabling plant for common cabling problems.
These include open circuits, short circuits, and impedance mismatches.
LinkMD works by sending a pulse of known amplitude and duration down the MDI or MDI-X pair, then analyzing the shape
of the reflected signal to determine the type of fault. The time duration for the reflected signal to return provides the
approximate distance to the cabling fault. The LinkMD function processes this TDR information and presents it as a
numerical value that can be translated to a cable distance.
LinkMD is initiated by accessing Register 1Dh, the LinkMD Control/Status register, in conjunction with Register 1Fh, the
PHY Control 2 register. The latter register is used to disable Auto MDI/MDI-X and to select either MDI or MDI-X as the
cable differential pair for testing.
Usage
The following is a sample procedure for using LinkMD with Registers 1Dh and 1Fh:
3. Disable auto MDI/MDI-X by writing a ‘1’ to Register 1Fh, bit [13].
4. Start cable diagnostic test by writing a ‘1’ to Register 1Dh, bit [15]. This enable bit is self-clearing.
5. Wait (poll) for Register 1Dh, bit [15] to return a ‘0’, and indicating cable diagnostic test is completed.
6. Read cable diagnostic test results in Register 1Dh, bits [14:13]. The results are as follows:
00 = normal condition (valid test)
01 = open condition detected in cable (valid test)
10 = short condition detected in cable (valid test)
11 = cable diagnostic test failed (invalid test)
The ‘11’ case, invalid test, occurs when the device is unable to shut down the link partner. In this instance, the test is
not run, since it would be impossible for the device to determine if the detected signal is a reflection of the signal
generated or a signal from another source.
7. Get distance to fault by concatenating Register 1Dh, bits [8:0] and multiplying the result by a constant of 0.38. The
distance to the cable fault can be determined by the following formula:
D (distance to cable fault) = 0.38 x (Register 1Dh, bits [8:0])
D (distance to cable fault) is expressed in meters.
Concatenated value of Registers 1Dh bits [8:0] should be converted to decimal before multiplying by 0.38.
The constant (0.38) may be calibrated for different cabling conditions, including cables with a velocity of propagation
that varies significantly from the norm.
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NAND Tree Support
The KSZ8081MNX/RNB provides parametric NAND tree support for fault detection between chip I/Os and board. The
NAND tree is a chain of nested NAND gates in which each KSZ8081MNX/RNB digital I/O (NAND tree input) pin is an
input to one NAND gate along the chain. At the end of the chain, the TXD1 pin provides the output for the nested NAND
gates.
The NAND tree test process includes:
• Enabling NAND tree mode
• Pulling all NAND tree input pins high
• Driving each NAND tree input pin low, sequentially, according to the NAND tree pin order
• Checking the NAND tree output to make sure there is a toggle high-to-low or low-to-high for each NAND tree input
driven low
Table 7 and Table 8 list the NAND tree pin orders for KSZ8081MNX and KSZ8081RNB, respectively.
Table 7. NAND Tree Test Pin Order for KSZ8081MNX
Pin Number
Pin Name
MDIO
NAND Tree Description
11
12
15
16
18
19
21
23
30
24
25
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Output
MDC
RXD1
RXD0
CRS_DV
REF_CLK
INTRP
TXEN
LED0
TXD0
TXD1
Note: KS8081MNX supports partial NAND tree test pins. Table 7 lists partial NAND tree test pins. If full NAND tree testing
is required, please use KSZ8091MNX device that supports all the required pins.
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Table 8. NAND Tree Test Pin Order for KSZ8081RNB
Pin Number
Pin Name
MDIO
NAND Tree Description
11
12
15
16
18
19
21
23
31
30
24
25
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Input
Output
MDC
RXD1
RXD0
CRS_DV
REF_CLK
INTRP
TXEN
LED1
LED0
TXD0
TXD1
NAND Tree I/O Testing
Use the following procedure to check for faults on the KSZ8081MNX/RNB digital I/O pin connections to the board:
1. Enable NAND tree mode using either hardware (NAND_Tree#, Pin 21) or software (Register 16h, Bit [5]).
2. Use board logic to drive all KSZ8081MNX/RNB NAND tree input pins high.
3. Use board logic to drive each NAND tree input pin, in KSZ8081MNX/RNB NAND tree pin order, as follows:
a. Toggle the first pin (MDIO) from high to low, and verify that the TXD1 pin switches from high to low to indicate that
the first pin is connected properly.
b. Leave the first pin (MDIO) low.
c. Toggle the second pin (MDC) from high to low, and verify that the TXD1 pin switches from low to high to indicate
that the second pin is connected properly.
d. Leave the first pin (MDIO) and the second pin (MDC) low.
e. Continue with this sequence until all KSZ8081MNX/RNB NAND tree input pins have been toggled.
Each KSZ8081MNX/RNB NAND tree input pin must cause the TXD1 output pin to toggle high-to-low or low-to-high to
indicate a good connection. If the TXD1 pin fails to toggle when the KSZ8081MNX/RNB input pin toggles from high to low,
the input pin has a fault.
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Power Management
The KSZ8081MNX/RNB incorporates a number of power-management modes and features that provide methods to
consume less energy. These are discussed in the following sections.
Power-Saving Mode
Power-saving mode is used to reduce the transceiver power consumption when the cable is unplugged. It is enabled by
writing a ‘1’ to Register 1Fh, Bit [10], and is in effect when auto-negotiation mode is enabled and the cable is disconnected
(no link).
In this mode, the KSZ8081MNX/RNB shuts down all transceiver blocks, except for the transmitter, energy detect, and PLL
circuits.
By default, power-saving mode is disabled after power-up.
Energy-Detect Power-Down Mode
Energy-detect power-down (EDPD) mode is used to further reduce transceiver power consumption when the cable is
unplugged. It is enabled by writing a ‘0’ to Register 18h, Bit [11], and is in effect when auto-negotiation mode is enabled
and the cable is disconnected (no link).
EDPD mode works with the PLL off (set by writing a ‘1’ to Register 10h, Bit [4] to automatically turn the PLL off in EDPD
mode) to turn off all KSZ8081MNX/RNB transceiver blocks except the transmitter and energy-detect circuits.
Power can be reduced further by extending the time interval between transmissions of link pulses to check for the
presence of a link partner. The periodic transmission of link pulses is needed to ensure the KSZ8081MNX/RNB and its
link partner, when operating 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.
Power-Down Mode
Power-down mode is used to power down the KSZ8081MNX/RNB 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 KSZ8081MNX/RNB disables all internal functions except the MII management interface. The
KSZ8081MNX/RNB exits (disables) power-down mode after Register 0h, Bit [11] is set back to ‘0’.
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 KSZ8081MNX/RNB 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 KSZ8081MNX/RNB 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].
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Reference Circuit for Power and Ground Connections
The KSZ8081MNX/RNB 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 10 and Table 9 for 3.3V VDDIO.
Figure 10. KSZ8081MNX/RNB Power and Ground Connections
Table 9. KSZ8081MNX/RNB Power Pin Descriptions
Power Pin
Pin Number
Description
VDD_1.2
2
Decouple with 2.2µF and 0.1µF capacitors to ground.
Connect to board’s 3.3V supply through a ferrite bead.
Decouple with 22µF and 0.1µF capacitors to ground.
Connect to board’s 3.3V supply for 3.3V VDDIO.
Decouple with 22µF and 0.1µF capacitors to ground.
VDDA_3.3
VDDIO
3
17
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Typical Current/Power Consumption
Table 10, Table 11, and Table 12 show typical values for current consumption by the transceiver (VDDA_3.3) and digital
I/O (VDDIO) power pins and typical values for power consumption by the KSZ8081MNX/RNB device for the indicated
nominal operating voltages. These current and power consumption values include the transmit driver current and on-chip
regulator current for the 1.2V core.
Transceiver (3.3V), Digital I/Os (3.3V)
Table 10. Typical Current/Power Consumption (VDDA_3.3 = 3.3V, VDDIO = 3.3V)
3.3V Transceiver
(VDDA_3.3)
3.3V Digital I/Os
(VDDIO)
Total Chip Power
Condition
mA
34
34
14
30
14
10
mA
12
13
11
11
10
10
mW
152
155
82.5
135
79.2
66.0
100Base-TX Link-up (no traffic)
100Base-TX Full-duplex @ 100% utilization
10Base-T Link-up (no traffic)
10Base-T Full-duplex @ 100% utilization
Power-saving mode (Reg. 1Fh, Bit [10] = 1)
EDPD mode (Reg. 18h, Bit [11] = 0)
EDPD mode (Reg. 18h, Bit [11] = 0) and PLL off (Reg. 10h,
Bit [4] = 1)
3.77
2.59
1.36
1.54
1.51
0.45
17.5
13.5
5.97
Software power-down mode (Reg. 0h, Bit [11] =1)
Software power-down mode (Reg. 0h, Bit [11] =1) and slow-
oscillator mode (Reg. 11h, Bit [5] =1)
Transceiver (3.3V), Digital I/Os (2.5V)
Table 11. Typical Current/Power Consumption (VDDA_3.3 = 3.3V, VDDIO = 2.5V)
3.3V Transceiver
2.5V Digital I/Os
(VDDIO)
Total Chip Power
(VDDA_3.3)
Condition
mA
mA
11
12
10
10
10
10
mW
140
142
74.5
114
74.5
61.3
100Base-TX Link-up (no traffic)
34
34
15
27
15
11
100Base-TX Full-duplex @ 100% utilization
10Base-T Link-up (no traffic)
10Base-T Full-duplex @ 100% utilization
Power-saving mode (Reg. 1Fh, Bit [10] = 1)
EDPD mode (Reg. 18h, Bit [11] = 0)
EDPD mode (Reg. 18h, Bit [11] = 0) and
PLL off (Reg. 10h, Bit [4] = 1)
3.55
2.29
1.15
1.35
1.34
0.29
15.1
10.9
4.52
Software power-down mode (Reg. 0h, Bit [11] =1)
Software power-down mode (Reg. 0h, Bit [11] =1) and
slow-oscillator mode (Reg. 11h, Bit [5] =1)
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Transceiver (3.3V), Digital I/Os (1.8V)
Table 12. Typical Current/Power Consumption (VDDA_3.3 = 3.3V, VDDIO = 1.8V)
3.3V Transceiver
1.8V Digital I/Os
Total Chip Power
(VDDA_3.3)
(VDDIO)
mA
11
Condition
mA
mW
132
134
65.7
105
65.7
52.5
100Base-TX Link-up (no traffic)
34
34
15
27
15
11
100Base-TX Full-duplex @ 100% utilization
10Base-T Link-up (no traffic)
12
9.0
10Base-T Full-duplex @ 100% utilization
Power-saving mode (Reg. 1Fh, Bit [10] = 1)
EDPD mode (Reg. 18h, Bit [11] = 0)
9.0
9.0
9.0
EDPD mode (Reg. 18h, Bit [11] = 0) and
PLL off (Reg. 10h, Bit [4] = 1)
4.05
2.79
1.65
1.21
1.21
0.19
15.5
11.4
5.79
Software power-down mode (Reg. 0h, Bit [11] =1)
Software power-down mode (Reg. 0h, Bit [11] =1) and
slow-oscillator mode (Reg. 11h, Bit [5] =1)
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Register Map
Register Number (Hex)
Description
0h
1h
Basic Control
Basic Status
2h
PHY Identifier 1
3h
PHY Identifier 2
4h
Auto-Negotiation Advertisement
Auto-Negotiation Link Partner Ability
Auto-Negotiation Expansion
Auto-Negotiation Next Page
Link Partner Next Page Ability
Reserved
5h
6h
7h
8h
9h
10h
11h
12h – 14h
15h
16h
17h
18h
19h – 1Ah
1Bh
1Ch
1Dh
1Eh
1Fh
Digital Reserved Control
AFE Control 1
Reserved
RXER Counter
Operation Mode Strap Override
Operation Mode Strap Status
Expanded Control
Reserved
Interrupt Control/Status
Reserved
LinkMD Control/Status
PHY Control 1
PHY Control 2
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KSZ8081MNX/KSZ8081RNB
Register Description
Address
Name
Description
Mode(10)
Default
Register 0h – Basic Control
1 = Software reset
0.15
0.14
Reset
0 = Normal operation
This bit is self-cleared after a ‘1’ is written to it.
1 = Loopback mode
0 = Normal operation
1 = 100Mbps
RW/SC
RW
0
Loopback
0
Set by the SPEED strapping pin.
0 = 10Mbps
0.13
0.12
Speed Select
RW
RW
See the Strapping Options –
KSZ8081MNX section for details.
This bit is ignored if auto-negotiation is enabled
(Register 0.12 = 1).
1 = Enable auto-negotiation process
0 = Disable auto-negotiation process
Set by the NWAYEN strapping
pin.
Auto-
Negotiation
Enable
See the Strapping Options –
KSZ8081MNX section for details.
If enabled, the auto-negotiation result overrides
the settings in registers 0.13 and 0.8.
1 = Power-down mode
0 = Normal operation
If software reset (Register 0.15) is used to exit
power-down mode (Register 0.11 = 1), two
software reset writes (Register 0.15 = 1) are
required. The first write clears power-down
mode; the second write resets the chip and re-
latches the pin strapping pin values.
0.11
Power-Down
RW
0
Set by the ISO strapping pin.
1 = Electrical isolation of PHY from MII/RMII
0 = Normal operation
0.10
0.9
Isolate
RW
See the Strapping Options –
KSZ8081MNX section for details.
1 = Restart auto-negotiation process
0 = Normal operation.
Restart Auto-
Negotiation
RW/SC
0
This bit is self-cleared after a ‘1’ is written to it.
The inverse of the DUPLEX
strapping pin value.
1 = Full-duplex
0 = Half-duplex
0.8
Duplex Mode
RW
See the Strapping Options –
KSZ8081MNX section for details.
1 = Enable COL test
0 = Disable COL test
Reserved
0.7
Collision Test
Reserved
RW
RO
0
0.6:0
000_0000
Note:
10. RW = Read/Write.
RO = Read only.
SC = Self-cleared.
LH = Latch high.
LL = Latch low.
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KSZ8081MNX/KSZ8081RNB
Register Description (Continued)
Address
Name
Description
Mode(10)
Default
Register 1h – Basic Status
1 = T4 capable
1.15
1.14
1.13
1.12
100Base-T4
RO
RO
RO
RO
0
1
1
1
0 = Not T4 capable
1 = Capable of 100Mbps full-duplex
0 = Not capable of 100Mbps full-duplex
1 = Capable of 100Mbps half-duplex
0 = Not capable of 100Mbps half-duplex
1 = Capable of 10Mbps full-duplex
0 = Not capable of 10Mbps full-duplex
1 = Capable of 10Mbps half-duplex
0 = Not capable of 10Mbps half-duplex
Reserved
100Base-TX
Full-Duplex
100Base-TX
Half-Duplex
10Base-T
Full-Duplex
10Base-T
Half-Duplex
1.11
1.10:7
1.6
RO
RO
RO
1
000_0
1
Reserved
1 = Preamble suppression
No Preamble
0 = Normal preamble
Auto-
Negotiation
Complete
1 = Auto-negotiation process completed
0 = Auto-negotiation process not completed
1.5
1.4
1.3
1.2
RO
RO/LH
RO
0
0
1
0
1 = Remote fault
Remote Fault
0 = No remote fault
Auto-
Negotiation
Ability
1 = Can perform auto-negotiation
0 = Cannot perform auto-negotiation
1 = Link is up
Link Status
RO/LL
0 = Link is down
1 = Jabber detected
1.1
1.0
Jabber Detect
RO/LH
RO
0
1
0 = Jabber not detected (default is low)
Extended
Capability
1 = Supports extended capability registers
Register 2h – PHY Identifier 1
Assigned to the 3rd through 18th bits of the
Organizationally Unique Identifier (OUI).
KENDIN Communication’s OUI is 0010A1
(hex).
PHY ID
2.15:0
RO
0022h
Number
Register 3h – PHY Identifier 2
Assigned to the 19th through 24th bits of the
Organizationally Unique Identifier (OUI).
KENDIN Communication’s OUI is 0010A1
(hex).
PHY ID
3.15:10
RO
0001_01
Number
3.9:4
3.3:0
Model Number Six-bit manufacturer’s model number
RO
RO
01_0110
Revision
Four-bit manufacturer’s revision number
Number
Indicates silicon revision
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KSZ8081MNX/KSZ8081RNB
Register Description (Continued)
Address
Name
Description
Mode(10)
Default
Register 4h – Auto-Negotiation Advertisement
1 = Next page capable
0 = No next page capability
Reserved
4.15
4.14
4.13
4.12
Next Page
Reserved
RW
RO
RW
RO
0
0
0
0
1 = Remote fault supported
0 = No remote fault
Remote Fault
Reserved
Reserved
[00] = No pause
[10] = Asymmetric pause
[01] = Symmetric pause
[11] = Asymmetric and symmetric pause
1 = T4 capable
4.11:10
Pause
RW
00
4.9
4.8
100Base-T4
RO
RW
0
0 = No T4 capability
Set by the SPEED strapping pin.
1 = 100Mbps full-duplex capable
100Base-TX
Full-Duplex
See the Strapping Options –
KSZ8081MNX section for details.
0 = No 100Mbps full-duplex capability
Set by the SPEED strapping pin.
1 = 100Mbps half-duplex capable
100Base-TX
Half-Duplex
4.7
4.6
RW
RW
See the Strapping Options –
KSZ8081MNX section for details.
0 = No 100Mbps half-duplex capability
1 = 10Mbps full-duplex capable
0 = No 10Mbps full-duplex capability
1 = 10Mbps half-duplex capable
0 = No 10Mbps half-duplex capability
[00001] = IEEE 802.3
10Base-T
Full-Duplex
1
10Base-T
Half-Duplex
4.5
RW
RW
1
4.4:0
Selector Field
0_0001
Register 5h – Auto-Negotiation Link Partner Ability
1 = Next page capable
5.15
5.14
Next Page
RO
RO
0
0
0 = No next page capability
1 = Link code word received from partner
0 = Link code word not yet received
1 = Remote fault detected
0 = No remote fault
Acknowledge
5.13
5.12
Remote Fault
Reserved
RO
RO
0
0
Reserved
[00] = No pause
[10] = Asymmetric pause
[01] = Symmetric pause
5.11:10
Pause
RO
00
[11] = Asymmetric and symmetric pause
1 = T4 capable
5.9
5.8
100Base-T4
RO
RO
0
0
0 = No T4 capability
1 = 100Mbps full-duplex capable
0 = No 100Mbps full-duplex capability
100Base-TX
Full-Duplex
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KSZ8081MNX/KSZ8081RNB
Register Description (Continued)
Address
Name
Description
Mode(10)
Default
Register 5h – Auto-Negotiation Link Partner Ability
1 = 100Mbps half-duplex capable
100Base-TX
Half-Duplex
5.7
5.6
RO
RO
0
0
0 = No 100Mbps half-duplex capability
1 = 10Mbps full-duplex capable
0 = No 10Mbps full-duplex capability
1 = 10Mbps half-duplex capable
0 = No 10Mbps half-duplex capability
[00001] = IEEE 802.3
10Base-T
Full-Duplex
10Base-T
Half-Duplex
5.5
RO
RO
0
5.4:0
Selector Field
0_0001
Register 6h – Auto-Negotiation Expansion
6.15:5
6.4
Reserved
Reserved
RO
0000_0000_000
0
1 = Fault detected by parallel detection
0 = No fault detected by parallel detection
1 = Link partner has next page capability
Parallel
Detection Fault
RO/LH
Link Partner
Next Page
Able
6.3
RO
0
0 = Link partner does not have next page
capability
1 = Local device has next page capability
Next Page
Able
6.2
6.1
RO
1
0
0 = Local device does not have next page
capability
1 = New page received
Page Received
RO/LH
0 = New page not received yet
Link Partner
Auto-
Negotiation
Able
1 = Link partner has auto-negotiation capability
6.0
RO
0
0 = Link partner does not have auto-negotiation
capability
Register 7h – Auto-Negotiation Next Page
1 = Additional next pages will follow
0 = Last page
7.15
7.14
7.13
Next Page
Reserved
RW
RO
RW
0
0
1
Reserved
1 = Message page
Message Page
0 = Unformatted page
1 = Will comply with message
0 = Cannot comply with message
7.12
Acknowledge2
Toggle
RW
0
1 = Previous value of the transmitted link code
word equaled logic 1
7.11
RO
RW
0
0 = Logic 0
7.10:0
Message Field 11-bit wide field to encode 2048 messages
000_0000_0001
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KSZ8081MNX/KSZ8081RNB
Register Description (Continued)
Address
Name
Description
Mode(10)
Default
Register 8h – Link Partner Next Page Ability
1 = Additional next pages will follow
0 = Last page
8.15
8.14
8.13
8.12
Next Page
Acknowledge
Message Page
Acknowledge2
RO
RO
RO
RO
0
0
0
0
1 = Successful receipt of link word
0 = No successful receipt of link word
1 = Message page
0 = Unformatted page
1 = Can act on the information
0 = Cannot act on the information
1 = Previous value of transmitted link code word
equal to logic 0
0 = Previous value of transmitted link code word
equal to logic 1
8.11
Toggle
RO
RO
0
8.10:0
Message Field 11-bit wide field to encode 2048 messages
000_0000_0000
Register 10h – Digital Reserved Control
10.15:5
Reserved
Reserved
RW
RW
RW
0000_0000_000
1 = Turn PLL off automatically in EDPD mode
0 = Keep PLL on in EDPD mode.
See also Register 18h, Bit [11] for EDPD mode
10.4
PLL Off
0
10.3:0
Reserved
Reserved
0000
Register 11h – AFE Control 1
11.15:6
Reserved
Reserved
RW
0000_0000_00
Slow-oscillator mode is used to disconnect the
input reference crystal/clock on the XI pin and
select the on-chip slow oscillator when the
KSZ8081MNX/RNB device is not in use after
Slow-Oscillator power-up.
11.5
RW
0
Mode Enable
1 = Enable
0 = Disable
This bit automatically sets software power-down
to the analog side when enabled.
11.4:0
Reserved
Reserved
RW
0_0000
0000h
Register 15h – RXER Counter
15.15:0 RXER Counter Receive error counter for symbol error frames
Register 16h – Operation Mode Strap Override
0 = Normal operation
RO/SC
1 = Factory test mode
0
Reserved
16.15
If TXC (Pin 22) latches in a pull-up value at the
de-assertion of reset, write a ‘0’ to this bit to
clear Reserved Factory Mode.
RW
Set by the pull-up/pull-down value
of TXC (Pin 22).
Factory Mode
This bit applies only to KSZ8081MNX.
16.14:11
16.10
Reserved
Reserved
Reserved
Reserved
RW
RO
000_0
0
B-CAST_OFF 1 = Override strap-in for B-CAST_OFF
Override If bit is ‘1’, PHY Address 0 is non-broadcast.
16.9
RW
0
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KSZ8081MNX/KSZ8081RNB
Register Description (Continued)
Address
Name
Description
Mode(10)
Default
Register 16h – Operation Mode Strap Override
16.8
16.7
Reserved
Reserved
RW
RW
0
0
1 = Override strap-in for MII back-to-back mode
(also set Bit 0 of this register to ‘1’)
MII B-to-B
Override
This bit applies only to KSZ8081MNX.
1 = Override strap-in for RMII Back-to-Back
mode (also set Bit 1 of this register to ‘1’)
RMII B-to-B
Override
16.6
RW
0
This bit applies only to KSZ8081RNB.
NAND Tree
Override
16.5
1 = Override strap-in for NAND tree mode
RW
RW
0
16.4:2
Reserved
Reserved
0_00
1 = Override strap-in for RMII mode
This bit applies only to KSZ8081RNB.
1 = Override strap-in for MII mode
This bit applies only to KSZ8081MNX.
16.1
16.0
RMII Override
RW
RW
0
1
MII Override
Register 17h – Operation Mode Strap Status
[000] = Strap to PHY Address 0
[001] = Strap to PHY Address 1
[010] = Strap to PHY Address 2
[011] = Strap to PHY Address 3
[100] = Strap to PHY Address 4
[101] = Strap to PHY Address 5
[110] = Strap to PHY Address 6
[111] = Strap to PHY Address 7
Reserved
PHYAD[2:0]
Strap-In Status
17.15:13
RO
17.12:10
17.9
Reserved
RO
RO
RO
RO
1 = Strap to B-CAST_OFF
B-CAST_OFF
Strap-In Status
If bit is ‘1’, PHY Address 0 is non-broadcast.
Reserved
17.8
Reserved
1 = Strap to MII back-to-back mode
This bit applies only to KSZ8081MNX.
1 = Strap to RMII Back-to-Back mode
This bit applies only to KSZ8081RNB.
MII B-to-B
Strap-In Status
17.7
RMII B-to-B
Strap-In Status
17.6
RO
NAND Tree
Strap-In Status
17.5
1 = Strap to NAND tree mode
RO
RO
17.4:2
Reserved
Reserved
1 = Strap to RMII mode
RMII Strap-In
Status
17.1
17.0
RO
RO
This bit applies only to KSZ8081RNB.
1 = Strap to MII mode
MII Strap-In
Status
This bit applies only to KSZ8081MNX.
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KSZ8081MNX/KSZ8081RNB
Register Description (Continued)
Address
Name
Description
Mode(10)
Default
Register 18h – Expanded Control
18.15:12
18.11
Reserved
Reserved
RW
0000
Energy-detect power-down mode
1 = Disable
EDPD
Disabled
RW
RW
1
0
0 = Enable
See also Register 10h, Bit [4] for PLL off.
1 = MII output is random latency
0 = MII output is fixed latency
100Base-TX
Latency
18.10
For both settings, all bytes of received preamble
are passed to the MII output.
This bit applies only to KSZ8081MNX.
Reserved
18.9:7
18.6
Reserved
RW
RW
RW
00_0
0
1 = Restore received preamble to MII output
10Base-T
Preamble
Restore
0 = Remove all seven bytes of preamble before
sending frame (starting with SFD) to MII output
This bit applies only to KSZ8081MNX,
Reserved
18.5:0
Reserved
00_0000
Register 1Bh – Interrupt Control/Status
Jabber
Interrupt
Enable
1 = Enable jabber interrupt
0 = Disable jabber interrupt
1B.15
1B.14
1B.13
1B.12
RW
RW
RW
RW
0
0
0
0
Receive Error
Interrupt
1 = Enable receive error interrupt
0 = Disable receive error interrupt
Enable
Page Received
Interrupt
1 = Enable page received interrupt
0 = Disable page received interrupt
Enable
Parallel Detect
Fault Interrupt
Enable
1 = Enable parallel detect fault interrupt
0 = Disable parallel detect fault interrupt
Link Partner
Acknowledge
Interrupt
1 = Enable link partner acknowledge interrupt
0 = Disable link partner acknowledge interrupt
1B.11
RW
0
Enable
Link-Down
Interrupt
Enable
1= Enable link-down interrupt
0 = Disable link-down interrupt
1B.10
1B.9
1B.8
RW
RW
RW
0
0
0
Remote Fault
Interrupt
1 = Enable remote fault interrupt
0 = Disable remote fault interrupt
Enable
Link-Up
Interrupt
Enable
1 = Enable link-up interrupt
0 = Disable link-up interrupt
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KSZ8081MNX/KSZ8081RNB
Register Description (Continued)
Address
Name
Description
Mode(10)
Default
Register 1Bh – Interrupt Control/Status
1 = Jabber occurred
Jabber
Interrupt
1B.7
1B.6
1B.5
1B.4
RO/SC
RO/SC
RO/SC
RO/SC
0
0
0
0
0 = Jabber did not occur
1 = Receive error occurred
Receive Error
Interrupt
0 = Receive error did not occur
1 = Page receive occurred
Page Receive
Interrupt
0 = Page receive did not occur
1 = Parallel detect fault occurred
0 = Parallel detect fault did not occur
Parallel Detect
Fault Interrupt
Link Partner
Acknowledge
Interrupt
1 = Link partner acknowledge occurred
1B.3
RO/SC
0
0 = Link partner acknowledge did not occur
1 = Link-down occurred
0 = Link-down did not occur
1 = Remote fault occurred
0 = Remote fault did not occur
1 = Link-up occurred
Link-Down
Interrupt
1B.2
1B.1
1B.0
RO/SC
RO/SC
RO/SC
0
0
0
Remote Fault
Interrupt
Link-Up
Interrupt
0 = Link-up did not occur
Register 1Dh – LinkMD Control/Status
1 = Enable cable diagnostic test. After test has
completed, this bit is self-cleared.
Cable
1D.15
Diagnostic
Test Enable
RW/SC
0
0 = Indicates cable diagnostic test (if enabled)
has completed and the status information is
valid for read.
[00] = Normal condition
[01] = Open condition has been detected in
cable
Cable
Diagnostic
Test Result
1D.14:13
RO
00
[10] = Short condition has been detected in
cable
[11] = Cable diagnostic test has failed
Short Cable
Indicator
1 = Short cable (<10 meter) has been detected
by LinkMD
1D.12
1D.11:9
1D.8:0
RO
RW
RO
0
Reserved
Reserved
000
Cable Fault
Counter
Distance to fault
0_0000_0000
Revision 1.4
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Register Description (Continued)
Address
Name
Description
Mode(10)
Default
Register 1Eh – PHY Control 1
1E.15:10
1E.9
Reserved
Reserved
RO
RO
0000_00
0
1 = Flow control capable
0 = No flow control capability
1 = Link is up
Enable Pause
(Flow Control)
1E.8
Link Status
RO
0
0 = Link is down
1 = Polarity is reversed
0 = Polarity is not reversed
Reserved
1E.7
1E.6
1E.5
Polarity Status
Reserved
RO
RO
RO
0
1 = MDI-X
MDI/MDI-X
State
0 = MDI
1 = Signal present on receive differential
pair
1E.4
1E.3
Energy Detect
PHY Isolate
RO
RW
0
0
0 = No signal detected on receive differential
pair
1 = PHY in isolate mode
0 = PHY in normal operation
[000] = Still in auto-negotiation
[001] = 10Base-T half-duplex
[010] = 100Base-TX half-duplex
[011] = Reserved
Operation
Mode
Indication
1E.2:0
RO
000
[100] = Reserved
[101] = 10Base-T full-duplex
[110] = 100Base-TX full-duplex
[111] = Reserved
Register 1Fh – PHY Control 2
1 = HP Auto MDI/MDI-X mode
0 = Micrel Auto MDI/MDI-X mode
When Auto MDI/MDI-X is disabled,
1 = MDI-X mode
1F.15
HP_MDIX
RW
RW
1
0
Transmit on RXP,RXM (pins 5, 4) and
Receive on TXP,TXM (pins 7, 6)
MDI/MDI-X
Select
1F.14
0 = MDI mode
Transmit on TXP,TXM (pins 7, 6) and
Receive on RXP,RXM (pins 5, 4)
1 = Disable Auto MDI/MDI-X
0 = Enable Auto MDI/MDI-X
Reserved
Pair Swap
Disable
1F.13
1F.12
RW
RW
0
0
Reserved
Revision 1.4
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KSZ8081MNX/KSZ8081RNB
Register Description (Continued)
Address
Name
Description
Mode(10)
Default
Register 1Fh – PHY Control 2
1 = Force link pass
0 = Normal link operation
1F.11
Force Link
RW
0
This bit bypasses the control logic and allows
the transmitter to send a pattern even if there is
no link.
1 = Enable power saving
0 = Disable power saving
1 = Interrupt pin active high
0 = Interrupt pin active low
1 = Enable jabber counter
0 = Disable jabber counter
1F.10
1F.9
1F.8
Power Saving
Interrupt Level
Enable Jabber
RW
RW
RW
0
0
1
1 = RMII 50MHz clock mode; clock input to XI
(Pin 9) is 50MHz
RMII
1F.7
1F.6
Reference
Clock Select
0 = RMII 25MHz clock mode; clock input to XI
(Pin 9) is 25MHz
RW
RW
0
0
This bit applies only to KSZ8081RNB.
Reserved
Reserved
LED Mode
[00] = LED1: Speed
LED0: Link/Activity
1F.5:4
[01] = LED1: Activity
LED0: Link
RW
00
[10], [11] = Reserved
1 = Disable transmitter
0 = Enable transmitter
1 = Remote (analog) loopback is enabled
0 = Normal mode
Disable
Transmitter
1F.3
1F.2
1F.1
1F.0
RW
RW
RW
RW
0
0
0
0
Remote
Loopback
1 = Enable SQE test
0 = Disable SQE test
1 = Disable scrambler
0 = Enable scrambler
Enable SQE
Test
Disable Data
Scrambling
Revision 1.4
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Micrel, Inc.
KSZ8081MNX/KSZ8081RNB
Absolute Maximum Ratings(11)
Operating Ratings(12)
Supply Voltage (VIN)
Supply Voltage
(VDD_1.2) .................................................. –0.5V to +1.8V
(VDDIO, VDDA_3.3) ...................................... –0.5V to +5.0V
Input Voltage (all inputs) .............................. –0.5V to +5.0V
Output Voltage (all outputs) ......................... –0.5V to +5.0V
Lead Temperature (soldering, 10s)............................ 260°C
Storage Temperature (TS).........................–55°C to +150°C
(VDDIO_3.3, VDDA_3.3).......................... +3.135V to +3.465V
(VDDIO_2.5)........................................ +2.375V to +2.625V
(VDDIO_1.8)........................................ +1.710V to +1.890V
Ambient Temperature
(TA, Commercial) ......................................0°C to +70°C
(TA, Industrial).......................................–40°C to +85°C
Maximum Junction Temperature (TJ(MAX)).................. 125°C
Thermal Resistance (θJA)...................................34°C/W
Thermal Resistance (θJC) ....................................6°C/W
Electrical Characteristics(13)
Symbol
Parameter
Condition
Min.
Typ.
Max.
Units
Supply Current (VDDIO, VDDA_3.3 = 3.3V)(14)
IDD1_3.3V
IDD2_3.3V
IDD3_3.3V
IDD4_3.3V
10Base-T
Full-duplex traffic @ 100% utilization
Full-duplex traffic @ 100% utilization
Ethernet cable disconnected (reg. 18h.11 = 0)
Software power-down (reg. 0h.11 = 1)
41
47
20
4
mA
mA
mA
mA
100Base-TX
EDPD Mode
Power-Down Mode
CMOS Level Inputs
VDDIO = 3.3V
VDDIO = 2.5V
VDDIO = 1.8V
VDDIO = 3.3V
VDDIO = 2.5V
VDDIO = 1.8V
VIN = GND ~ VDDIO
2.0
1.8
1.3
VIH
Input High Voltage
V
0.8
0.7
0.5
10
VIL
Input Low Voltage
Input Current
V
|IIN|
µA
CMOS Level Outputs
VDDIO = 3.3V
VDDIO = 2.5V
VDDIO = 1.8V
VDDIO = 3.3V
VDDIO = 2.5V
VDDIO = 1.8V
2.4
2.0
1.5
VOH
Output High Voltage
V
0.4
0.4
0.3
10
VOL
Output Low Voltage
V
|Ioz|
Output Tri-State Leakage
Output Drive Current
µA
mA
LED Output
ILED
Each LED pin (LED0, LED1)
8
Notes:
11. Exceeding the absolute maximum ratings can damage the device. Stresses greater than the absolute maximum rating can cause permanent
damage to the device. Operation of the device at these or any other conditions above those specified in the operating sections of this specification is
not implied. Maximum conditions for extended periods may affect reliability.
12. The device is not guaranteed to function outside its operating ratings.
13. TA = 25°C. Specification for packaged product only.
14. Current consumption is for the single 3.3V supply KSZ8081MNX/RNB device only, and includes the transmit driver current and the 1.2V supply
voltage (VDD_1.2) that are supplied by the KSZ8081MNX/RNB.
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Electrical Characteristics(13) (Continued)
Symbol
Parameter
Condition
Min.
Typ.
Max.
Units
kΩ
All Pull-Up/Pull-Down Pins (including Strapping Pins)
VDDIO = 3.3V
30
39
48
26
34
53
45
61
99
43
59
99
73
pu
pd
Internal Pull-Up Resistance
VDDIO = 2.5V
VDDIO = 1.8V
VDDIO = 3.3V
VDDIO = 2.5V
VDDIO = 1.8V
102
178
79
Internal Pull-Down Resistance
113
200
kΩ
100Base-TX Transmit (measured differentially after 1:1 transformer)
VO
Peak Differential Output Voltage 100Ω termination across differential output
0.95
1.05
2
V
VIMB
tr, tf
Output Voltage Imbalance
Rise/Fall Time
100Ω termination across differential output
%
3
0
5
ns
ns
ns
%
Rise/Fall Time Imbalance
Duty Cycle Distortion
Overshoot
0.5
±0.25
5
Output Jitter
Peak-to-peak
0.7
ns
10Base-T Transmit (measured differentially after 1:1 transformer)
VP
Peak Differential Output Voltage 100Ω termination across differential output
2.2
2.8
3.5
V
Jitter Added
Peak-to-peak
ns
ns
tr, tf
Rise/Fall Time
25
10Base-T Receive
VSQ
Squelch Threshold
5MHz square wave
400
0.65
mV
V
Transmitter – Drive Setting
VSET
Reference Voltage of ISET
R(ISET) = 6.49kΩ
REF_CLK Output
Peak-to-peak. (Applies only to KSZ8081RNB
in RMII – 25MHz clock mode)
50MHz RMII Clock Output Jitter
300
20
ps
ns
100Mbps Mode – Industrial Applications Parameters
XI (25MHz clock input) to MII TXC (25MHz
Clock Phase Delay – XI Input to clock output) delay, referenced to rising edges
15
25
MII TXC Output
of both clocks. (Applies only to KSZ8081MNX
in MII mode)
Link loss detected at receive differential inputs
to PHY signal indication time for each of the
following:
1. For LED mode 00, Speed LED output
changes from low (100Mbps) to high (10Mbps,
default state for link-down).
Link Loss Reaction (Indication)
Time
tllr
4.4
µs
2. For LED mode 01, Link LED output changes
from low (link-up) to high (link-down).
3. INTRP pin asserts for link-down status
change.
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Timing Diagrams
MII SQE Timing (10Base-T)
Figure 11. MII SQE Timing (10Base-T)
Table 13. MII SQE Timing (10Base-T) Parameters
Timing Parameter
Description
Min.
Typ.
400
200
200
2.2
Max.
Units
ns
tP
TXC period
tWL
TXC pulse width low
TXC pulse width high
COL (SQE) delay after TXEN de-asserted
COL (SQE) pulse duration
ns
tWH
tSQE
tSQEP
ns
µs
1.0
µs
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MII Transmit Timing (10Base-T)
Figure 12. MII Transmit Timing (10Base-T)
Table 14. MII Transmit Timing (10Base-T) Parameters
Timing Parameter
Description
Min.
Typ.
400
200
200
Max.
Units
ns
tP
TXC period
tWL
TXC pulse width low
ns
tWH
TXC pulse width high
ns
tSU1
tSU2
tHD1
tHD2
tCRS1
tCRS2
TXD[3:0] setup to rising edge of TXC
TXEN setup to rising edge of TXC
TXD[3:0] hold from rising edge of TXC
TXEN hold from rising edge of TXC
TXEN high to CRS asserted latency
TXEN low to CRS de-asserted latency
120
120
0
ns
ns
ns
0
ns
600
1.0
ns
µs
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KSZ8081MNX/KSZ8081RNB
MII Receive Timing (10Base-T)
Figure 13. MII Receive Timing (10Base-T)
Table 15. MII Receive Timing (10Base-T) Parameters
Timing Parameter
Description
Min.
Typ.
400
200
200
Max.
Units
ns
tP
RXC period
tWL
tWH
RXC pulse width low
RXC pulse width high
ns
ns
(RXDV, RXD[3:0], RXER) output delay from rising
edge of RXC
tOD
205
7.2
ns
µs
tRLAT
CRS to (RXDV, RXD[3:0]) latency
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MII Transmit Timing (100Base-TX)
Figure 14. MII Transmit Timing (100Base-TX)
Table 16. MII Transmit Timing (100Base-TX) Parameters
Timing Parameter
Description
Min.
Typ.
40
Max.
Units
ns
tP
TXC period
tWL
TXC pulse width low
20
ns
tWH
TXC pulse width high
20
ns
tSU1
tSU2
tHD1
tHD2
tCRS1
tCRS2
TXD[3:0] setup to rising edge of TXC
TXEN setup to rising edge of TXC
TXD[3:0] hold from rising edge of TXC
TXEN hold from rising edge of TXC
TXEN high to CRS asserted latency
TXEN low to CRS de-asserted latency
10
10
0
ns
ns
ns
0
ns
72
72
ns
ns
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MII Receive Timing (100Base-TX)
Figure 15. MII Receive Timing (100Base-TX)
Table 17. MII Receive Timing (100Base-TX) Parameters
Timing Parameter
Description
Min.
Typ.
40
Max.
Units
ns
tP
RXC period
tWL
tWH
RXC pulse width low
RXC pulse width high
20
ns
20
ns
(RXDV, RXD[3:0], RXER) output delay from rising
edge of RXC
tOD
16
21
25
ns
ns
tRLAT
CRS to (RXDV, RXD[3:0] latency
170
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KSZ8081MNX/KSZ8081RNB
RMII Timing
Figure 16. RMII Timing – Data Received from RMII
Figure 17. RMII Timing – Data Input to RMII
Table 18. RMII Timing Parameters – KSZ8081RNB (25MHz input to XI pin, 50MHz output from REF_CLK pin)
Timing Parameter
Description
Clock cycle
Setup time
Hold time
Min.
Typ.
Max.
Units
ns
tCYC
t1
20
4
2
7
ns
t2
ns
tOD
Output delay
10
13
ns
Table 19. RMII Timing Parameters – KSZ8081RNB (50MHz input to XI pin)
Timing Parameter
Description
Clock cycle
Setup time
Hold time
Min.
Typ.
Max.
Units
ns
tCYC
t1
20
4
2
8
ns
t2
ns
tOD
Output delay
11
13
ns
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KSZ8081MNX/KSZ8081RNB
Auto-Negotiation Timing
Figure 18. Auto-Negotiation Fast Link Pulse (FLP) Timing
Table 20. Auto-Negotiation Fast Link Pulse (FLP) Timing Parameters
Timing Parameter
Description
Min.
Typ.
16
Max.
Units
ms
ms
ns
tBTB
tFLPW
tPW
FLP burst to FLP burst
FLP burst width
8
24
2
Clock/Data pulse width
Clock pulse to data pulse
Clock pulse to clock pulse
Number of clock/data pulses per FLP burst
100
64
tCTD
tCTC
55.5
111
17
69.5
139
33
µs
128
µs
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MDC/MDIO Timing
Figure 19. MDC/MDIO Timing
Table 21. MDC/MDIO Timing Parameters
Timing Parameter
Description
Min.
Typ.
2.5
Max.
Units
MHz
ns
fc
MDC Clock Frequency
MDC period
10
tP
400
tMD1
tMD2
tMD3
MDIO (PHY input) setup to rising edge of MDC
MDIO (PHY input) hold from rising edge of MDC
MDIO (PHY output) delay from rising edge of MDC
10
4
ns
ns
5
222
ns
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KSZ8081MNX/KSZ8081RNB
Power-up/Reset Timing
The KSZ8081MNX/RNB reset timing requirement is summarized in Figure 20 and Table 22.
Figure 20. Power-up/Reset Timing
Table 22. Power-up/Reset Timing Parameters
Parameter
Description
Min.
300
10
5
Max.
Units
µs
tVR
tSR
tCS
tCH
tRC
Supply voltage (VDDIO, VDDA_3.3) rise time
Stable supply voltage (VDDIO, VDDA_3.3) to reset high
Configuration setup time
ms
ns
Configuration hold time
5
ns
Reset to strap-in pin output
6
ns
The supply voltage (VDDIO and VDDA_3.3) power-up waveform should be monotonic. The 300µs minimum rise time is from
10% to 90%.
For warm reset, the reset (RST#) pin should be asserted low for a minimum of 500µs. The strap-in pin values are read
and updated at the de-assertion of reset.
After the de-assertion of reset, wait a minimum of 100µs before starting programming on the MIIM (MDC/MDIO) interface.
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KSZ8081MNX/KSZ8081RNB
Reset Circuit
Figure 21 shows a reset circuit recommended for powering up the KSZ8081MNX/RNB if reset is triggered by the power
supply.
Figure 21. Recommended Reset Circuit
Figure 22 Shows a reset circuit recommended for applications where reset is driven by another device (for example, the
CPU or an FPGA). The reset out RST_OUT_n from CPU/FPGA provides the warm reset after power up reset. D2 is used
if using different VDDIO between the switch and CPU/FPGA, otherwise, the different VDDIO will fight each other. If
different VDDIO have to use in a special case, a low VF (<0.3V) diode is required (For example, VISHAY’s BAT54,
MSS1P2L and so on), or a level shifter device can be used too. If Ethernet device and CPU/FPGA use same VDDIO
voltage, D2 can be removed to connect both devices directly. Usually, Ethernet device and CPU/FPGA should use same
VDDIO voltage.
VDDIO
R 10K
D1
CPU/FPGA
KSZ8081MNX/RNB
RST
RST_OUT_n
D2
C 10uF
Figure 22. Recommended Reset Circuit for Interfacing with CPU/FPGA Reset Output
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KSZ8081MNX/KSZ8081RNB
Reference Circuits – LED Strap-In Pins
The pull-up, float, and pull-down reference circuits for the LED1/SPEED and LED0/NWAYEN strapping pins are shown in
Figure 23 for 3.3V and 2.5V VDDIO.
Figure 23. Reference Circuits for LED Strapping Pins
For using 1.8V VDDIO, should select parts with low 1.8V operation voltage and forwarding current IF about 2mA LED
indicator. It is ok using internal pull-up or external pull-up resistor for the LED pin pull-up strap function, and use an
external 0.75K to 1K pull-down resistor for the LED pin pull-down strap function.
Note: If using RJ45 jacks with integrated LEDs and 1.8V VDDIO, a level shifting is required from LED 3.3V to 1.8V. For
example, use a bipolar transistor or a level shift device.
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KSZ8081MNX/KSZ8081RNB
Reference Clock – Connection and Selection
A crystal or external clock source, such as an oscillator, is used to provide the reference clock for the KSZ8081MNX/RNB.
For the KSZ8081MNX in all operating modes and for the KSZ8081RNB in RMII – 25MHz Clock Mode, the reference clock
is 25MHz. The reference clock connections to XI (Pin 9) and XO (Pin 8), and the reference clock selection criteria, are
provided in Figure 24 and Table 23.
Figure 24. 25MHz Crystal/Oscillator Reference Clock Connection
Table 23. 25MHz Crystal/Reference Clock Selection Criteria
Characteristics
Value
25
Units
MHz
ppm
Ω
Frequency
Frequency tolerance (max)(15)
Crystal series resistance (typ)
Crystal load capacitance (typ)
±50
40
22
pF
Note:
15. ±60ppm for overtemperature crystal.
For the KSZ8081RNB in RMII – 50MHz clock mode, the reference clock is 50MHz. The reference clock connections to XI
(Pin 9), and the reference clock selection criteria are provided in Figure 25 and Table 24.
Figure 25. 50MHz Oscillator Reference Clock Connection
Table 24. 50MHz Oscillator/Reference Clock Selection Criteria
Characteristics
Value
50
Units
MHz
ppm
Frequency
Frequency tolerance (maximum)
±50
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KSZ8081MNX/KSZ8081RNB
Magnetic – Connection and Selection
A 1:1 isolation transformer is required at the line interface. Use one with integrated common-mode chokes for designs
exceeding FCC requirements.
The KSZ8081MNX/RNB design incorporates voltage-mode transmit drivers and on-chip terminations.
With the voltage-mode implementation, the transmit drivers supply the common-mode voltages to the two differential
pairs. Therefore, the two transformer center tap pins on the KSZ8081MNX/RNB side should not be connected to any
power supply source on the board; instead, the center tap pins should be separated from one another and connected
through separate 0.1µF common-mode capacitors to ground. Separation is required because the common-mode voltage
is different between transmitting and receiving differential pairs.
Figure 26 shows the typical magnetic interface circuit for the KSZ8081MNX/RNB.
Figure 26. Typical Magnetic Interface Circuit
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Table 25 lists recommended magnetic characteristics.
Table 25. Magnetics Selection Criteria
Parameter
Value
Test Condition
Turns ratio
1 CT : 1 CT
350µH
Open-circuit inductance (minimum)
Insertion loss (typical)
HIPOT (minimum)
100mV, 100kHz, 8mA
100kHz to 100MHz
–1.1dB
1500Vrms
Table 26 is a list of compatible single-port magnetics with separated transformer center tap pins on the PHY chip side that
can be used with the KSZ8081MNX/RNB.
Table 26. Compatible Single-Port 10/100 Magnetics
Manufacturer
Bel Fuse
Bel Fuse
Bel Fuse
Delta
Part Number
S558-5999-U7
SI-46001-F
SI-50170-F
LF8505
Temperature Range
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
–40°C to 85°C
0°C to 70°C
0°C to 70°C
–40°C to 85°C
Magnetic + RJ-45
No
Yes
Yes
No
HALO
HFJ11-2450E
TG110-E055N5
LF-H41S-1
H1102
Yes
No
HALO
LANKom
Pulse
No
No
Pulse
H1260
No
Pulse
HX1188
No
Pulse
J00-0014
Yes
Yes
Yes
No
Pulse
JX0011D21NL
TLA-6T718A
HB726
TDK
Transpower
Wurth/Midcom
000-7090-37R-LF1
No
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KSZ8081MNX/KSZ8081RNB
Package Information and Recommended Land Pattern(16)
32-Pin 5mm × 5mm QFN
Note:
16. Package information is correct as of the publication date. For updates and most current information, go to www.micrel.com.
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MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com
Micrel, Inc. is a leading global manufacturer of IC solutions for the worldwide high performance linear and power, LAN, and timing & communications
markets. The Company’s products include advanced mixed-signal, analog & power semiconductors; high-performance communication, clock
management, MEMs-based clock oscillators & crystal-less clock generators, Ethernet switches, and physical layer transceiver ICs. Company
customers include leading manufacturers of enterprise, consumer, industrial, mobile, telecommunications, automotive, and computer products.
Corporation headquarters and state-of-the-art wafer fabrication facilities are located in San Jose, CA, with regional sales and support offices and
advanced technology design centers situated throughout the Americas, Europe, and Asia. Additionally, the Company maintains an extensive network
of distributors and reps worldwide.
Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this datasheet. This
information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry,
specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual
property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability
whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product
can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant
into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A
Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully
indemnify Micrel for any damages resulting from such use or sale.
© 2013 Micrel, Incorporated.
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