AMD AM79C875

D A T A
S H E E T
Am79C875
NetPHY™ 4LP Low Power Quad 10/100-TX/FX Ethernet Transceiver
DISTINCTIVE CHARACTERISTICS
■ Four 10/100BASE-TX Ethernet PHY transceivers
■ Supports RMII (Reduced MII) interface
■ Automatic Polarity Detection during AutoNegotiation and 10BASE-T signal reception
■ 125 meter (m) MLT-3 and Baseline Wander
operation
■ Unique scramble seed per port reduces EMI in
switch and repeater applications
■ Low power consumption
■ One port supports 100BASE-FX function
— 1.3 Watt (W) typical (1:1 magnetics)
— 1.2 W typical (1.25:1 magnetics)
■ Power management modes:
— Selectable 1:1 or 1.25:1 transmit transformer
— Unplugged - approximately 100 mW per port
— Power Down - approximately 3 mW per port
■ Single 3.3 V power supply with 5 V I/O tolerance
■ Patent-pending DC restoration technique
reduces baseline wander susceptibility
■ Full and half-duplex operation with full-featured
Auto-Negotiation function
■ Next Page register support
■ Supports Inter Packet Gap as low as 40 ns for
high throughput applications
■ No external filters or chokes required
■ Compliant with IEEE 802.3 standards for
100BASE-TX, 100BASE-FX, and 10BASE-T
■ Built-in loopback and test modes
■ Small 14 x 20 mm 100-pin PQR package
■ Small package allows side-by-side PHY layout
— Fits neatly behind quad magnetics
— Saves board space over larger 208 PQFP
packages
■ Support for Industrial Temperature
(-40°C to +85°C)
GENERAL DESCRIPTION
The NetPHY™ 4LP device is a highly integrated, low
power 10BASE-T/100BASE-TX/FX Quad Ethernet
transceiver. The NetPHY™ 4LP device includes
integrated RMII, ENDECs, Scrambler/Descrambler,
and full-featured Auto-Negotiation with support for Parallel Detection and Next Page. Port 3 can be configured as a 100BASE-FX transmitter to output an NRZI
PECL level signal. Each receiver has an adaptive
equalizer/DC restoration circuit for accurate clock/data
recovery on the 100BASE-TX signal at different cable
lengths and can perform to 125 m and beyond.
The NetPHY™ 4LP device operates on a 3.3 V supply
and offers 5 V I/O tolerance for mixed signal designs.
Power consumption is 1.3 W typical for the device, or
0.3 W per port using 1:1 magnetics. The NetPHY™
4LP device can use 1.25:1 magnetics, which decreases transmit power consumption and reduces device power consumption to 1.2 W typical.
The NetPHY™ 4LP device offers an optimized pinout
for network applications. RMII pins can be routed di-
rectly to the MAC and TX/RX media pins are routed directly to the magnetics. Direct routing of high speed
traces is imperative for project system design and EMI
noise reduction.
The NetPHY™ 4LP device’s on-chip input filtering and
output waveshaping eliminates the need of external hybrid filters for media connection. Integrated LED logic
allows three LEDs per port to be driven directly. These
features greatly simplify the design of a 100BASE-X repeater/switch board, thus requiring minimum external
components.
For ease of system and chip setup and testing, the NetPHY™ 4LP device offers loopback and various advanced testing and monitoring capabilities.
The NetPHY™ 4LP device is available in the Commercial (0°C to 70°C) or Industrial (-40°C to +85°C) temperature ranges. The Industrial temperature range is
well suited to environment such as enclosures with restricted air flow or outdoor equipment.
Publication# 22236 Rev: H Amendment/0
Issue Date: February 2003
Refer to AMD’s Website (www.amd.com) for the latest information.
BLOCK DIAGRAM (PER PORT)
PCS
Framer
Carrier Detect
4B/5B
100TX
TP_PMD
MLT-3
BLW
Stream Cipher
100RX
PMA
Clock Recovery
Link Monitor
Signal Detect
RMII Data
Interface
TX+
TX-
25 MHz
Interface
Mux
10TX
10BASE-T
MAC
10RX
RX+
Transformer
RX-
MDC/MDIO
Control/Status
20 MHz
RX
MII Serial Management
Interface and Registers
PHYAD[4:0]
PLL Clk Generator
Test LED Control
25 MHz
FLP
AutoNegotiation
REFCLK TEST LED
[3:0] Drivers
22236G-1
2
Am79C875
CONNECTION DIAGRAM
22236G-2
Am79C875
3
LOGIC SYMBOL
4
Am79C875
ORDERING INFORMATION
Standard Products
AMD standard products are available in several packages and operating ranges. The order number (Valid Combination) is formed
by a combination of the elements below.
AM79C875
K
C/I
ALTERNATE PACKAGING OPTION
TEMPERATURE RANGE
C = Commercial (0°C to +70°C)
I = Industrial (-40°C to +85°C)
PACKAGE TYPE
K = 100-Pin Plastic Quad Flat Pack (PQR100)
SPEED OPTION
Not Applicable
DEVICE NUMBER/DESCRIPTION
AM79C875
NetPHY™ 4LP Low Power Quad 10/100-TX/FX
Ethernet Transceiver
Valid Combinations
Valid Combinations
AM79C875
KC
AM79C875
KI
Valid Combinations list configurations planned to be supported in volume for this device. Consult the local AMD sales
office to confirm availability of specific valid combinations and
to check on newly released combinations.
Am79C875
5
RELATED AMD PRODUCTS
Part No.
Description
Integrated Controllers
Am97C973B/975B PCnet-FAST™ III Single-Chip 10/100 Mbps PCI Ethernet Controller with Integrated PHY
Am79C976
PCnet-PRO™ 10/100 Mbps PCI Ethernet Controller
Am79C978A
PCnet-Home™ Single-Chip 1/10 Mbps PCI Home Networking Controller
Physical Layer Devices (Single-Port)
Am79C874
NetPHY™ 1LP Low Power 10/100-TX/FX Ethernet Transceiver
Am79C901A
HomePHY™ Single-Chip 1/10 Mbps Home Networking PHY
6
Am79C875
TABLE OF CONTENTS
DISTINCTIVE CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
GENERAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1
BLOCK DIAGRAM (PER PORT). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
CONNECTION DIAGRAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
LOGIC SYMBOL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
ORDERING INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Standard Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
RELATED AMD PRODUCTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
PIN DESIGNATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
PIN DESCRIPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Media Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
100BASE-FX Function/Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Clock . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
RMII Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
LED Port . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Power and Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Modes of Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
100BASE-X Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
10BASE-T Block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Auto-Negotiation and Miscellaneous Functions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Loopback Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Power Savings Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
LED Port Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
PHY Control and Management Block (PCM Block) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
ABSOLUTE MAXIMUM RATINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Operating Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
DC CHARACTERISTICS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
Power Supply Current Consumption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
SWITCHING WAVEFORMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Key to Switching Waveforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
SWITCHING CHARACTERISTICS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
System Clock Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
MLT-3 Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
MII Management Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Independent RMII Mode Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
PHYSICAL DIMENSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
PQR100 (measured in millimeters) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45
ERRATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
Revision B.4 Errata Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
Errata for NetPHY™ 4LP B.4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
REVISION SUMMARY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Revision C to D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Revision D to E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Revision E to F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Revision F to G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Revision G to H . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Am79C875
7
LIST OF FIGURES
Figure 1. 100 Mbps Reception with No Errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Figure 2. 100 Mbps Reception with False Carrier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Figure 3. 100 Mbps Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Figure 4. Bit Ordering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Figure 5. 10BASE-T Transmit/Receive Data Paths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Figure 6. MLT-3 Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
Figure 7. TX± and RX± Termination for 100BASE-TX and 10BASE-T . . . . . . . . . . . . . . . . . .20
Figure 8. LED Port Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Figure 9. PHY Management Read and Write Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Figure 10. MLT-3 Receive Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
Figure 11. MLT-3 and 10BASE-T Test Load with 1:1 Transformer Ratio . . . . . . . . . . . . . . . . . .37
Figure 12. MLT-3 and 10BASE-T Test Load with 1.25:1 Transformer Ratio . . . . . . . . . . . . . . .37
Figure 13. Near-End 100BASE-TX Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
Figure 14. Near-End 10BASE-T Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Figure 15. Recommended PECL Test Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38
Figure 16. Clock Signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Figure 17. MLT-3 Test Waveform . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .39
Figure 18. Management Bus Transmit Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Figure 19. Management Bus Receive Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
Figure 20. RMII 100 Mbps Transmit Start of Packet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Figure 21. RMII 100 Mbps Transmit End of Packet Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Figure 22. 100 Mbps RMII Receive Start of Packet Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Figure 23. 100 Mbps RMII Receive End of Packet Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42
Figure 24. RMII 10 Mbps Transmit Start of Packet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Figure 25. RMII 10 Mbps Transmit End of Packet Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43
Figure 26. 10 Mbps RMII Receive Start of Packet Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
Figure 27. 10 Mbps RMII Receive End of Packet Timing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
LIST OF TABLES
Table 1.
Code-Group Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
Table 2.
LED Display Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Table 3.
Clause 22 Management Frame Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Table 4.
PHY Address Setting Frame Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Table 5.
NetPHY™ 4LP MII Management Register Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
Table 6.
Legend for Register Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25
Table 7.
MII Management Control Register (Register 0) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26
Table 8.
MII Management Status Register (Register 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
Table 9.
PHY Identifier 1 Register (Register 2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Table 10. PHY Identifier 2 Register (Register 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
Table 11. Auto-Negotiation Advertisement Register (Register 4) . . . . . . . . . . . . . . . . . . . . . . .28
Table 12. Auto-Negotiation Link Partner Ability Register in Base Page Format (Register 5) . .29
Table 13. Auto-Negotiation LInk Partner Ability Register in Next Page Format (Register 5) . .29
Table 14. Auto-Negotiation Expansion Register (Register 6) . . . . . . . . . . . . . . . . . . . . . . . . . .30
Table 15. Auto-Negotiation Next page Advertisement Register (Register 7) . . . . . . . . . . . . . .30
Table 16. Miscellaneous Features Register (Register 16) . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Table 17. Interrupt Control/Status Register (Register 17) . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
Table 18. Diagnostic Register (Register 18) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Table 19. Test Register (Register 19) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Table 20. Miscellaneous Features 2 Register (Register 20) . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Table 21. Receive Error Counter (Register 21) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
Table 22. Mode Control Register (Register 24) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
8
Am79C875
PIN DESIGNATIONS
Listed by Pin Number
Pin
No.
Pin Name
Pin
No.
Pin Name
Pin
No.
Pin Name
1
RX[0]-
26
TX[3]+
51
TXD[3]_[0]
76
TX_EN[1]
2
RX[0]+
27
AGND
52
OGND
77
CVDD
3
AGND
28
AGND
53
TX_EN[3]
78
RXD[0]_[1]
4
AGND
29
RX[3]+
54
CVDD
79
RXD[0]_[0]
5
TX[0]+
30
RX[3]-
55
RXD[2]_[1]
80
OVDD
6
TX[0]-
31
AVDD
56
RXD[2]_[0]
81
RX_ER[0]
7
AVDD
32
SDI+/TEST[0]
57
RX_ER[2]
82
CRS_DV[0]/
8
AVDD
33
SDI-/TEST[1]
58
CRS_DV[2]
83
CGND
9
TX[1]-
34
FXR+/TEST[2]
59
CGND
84
TXD[0]_[1]
10
TX[1]+
35
FXR-/TEST[3]
60
TXD[2]_[1]
85
TXD[0]_[0]
11
AGND
36
FXT+
61
TXD[2]_[0]
86
TX_EN[0]
12
AGND
37
FXT-
62
OVDD
87
OGND
13
RX[1]+
38
LEDDPX[3]/
SCRAM_EN
63
TX_EN[2]
88
LEDDPX[1]/
PHYAD[4]
14
RX[1]-
39
LEDACT_LINK[3]/
ANEGA
64
MDIO
89
LEDACT_LINK[1]/
PHYAD[3]
15
AVDD
40
LEDSPD[3]/
BURN_IN
65
MDC
90
LEDSPD[1]/
PHYAD[2]
16
AVDD
41
LEDDPX[2]/DPLX
66
REFCLK
91
LEDDPX[0]/FX_DIS
17
RX[2]-
42
LEDACT_LINK[2]
67
CVDD
92
LEDACT_LINK[0]
18
RX[2]+
43
LEDSPD[2]/
FORCE100
68
RXD[1]_[1]
93
LEDSPD[0]/TP1_1
19
AGND
44
OVDD
69
RXD[1]_[0]
94
INTR
20
AGND
45
RXD[3]_[1]
70
RX_ER[1]
95
RST
21
TX[2]+
46
RXD[3]_[0]
71
CRS_DV[1]
96
GAGND
72
OGND
97
IBREF
Pin No. Pin Name
22
TX[2]-
47
RX_ER[3]/
PHYAD_ST
23
AVDD
48
CRS_DV[3]
73
CGND
98
GAVDD
24
AVDD
49
CGND
74
TXD[1]_[1]
99
GAVDD
25
TX[3]-
50
TXD[3]_[1]
75
TXD[1]_[0]
100
AVDD
Am79C875
9
PIN DESCRIPTIONS
Media Connections
FXT±
Fiber Transmit Output
(For Port 3 only)
TX[3:0]±
Transmit Output
When Port 3 is configured as FX Channel, FXT± are
ECL level FX transmit pins.
Output
The TX[3:0]± pins are the differential transmit output
pairs. The TX[3:0]± pins transmit 10BASE-T or MLT-3
signals depending on the state of the link of the port.
RX[3:0]±
Receive Input
Input
The RX[3:0]± pins are the differential receive input
pairs. The RX[3:0]± pins can receive 10BASE-T or
MLT-3 signals depending on the state of the link of the
port.
100BASE-FX Function/Test
SDI+/TEST[0]
Signal Detect Input+
(For Port 3 only)
Analog Output
Clock
REFCLK
Reference Clock Input Signal
Input
The REFCLK pin is the reference clock input. The
REFCLK signal must be a 50-MHz signal.
RMII Signals
TXD[3:0]_[1:0]
RMII TXD for Ports 0 to 3
Input
These pins are the transmit data input to the RMII of
Ports 0:3.
Analog Input/Output
TX_EN[3:0]
RMII Transmit Enable
Input
This pin indicates signal quality status on the fiber-optic
link in 100BASE-FX mode. When the signal quality is
good, the SDI+ pin should be driven high relative to the
SDI- pin. 100BASE-FX is disabled when both pins are
simultaneously pulled low. SDI- can also be used for
Signal Detect Common Mode Voltage input.
These pins are the transmit enable inputs to the RMII.
When in test mode, SDI+, SDI-, FXR+, and FXR- pins
are used as TEST[3:0].
Output
SDI-/TEST[1]
Signal Detect Input(For Port 3 only)
Analog Input/Output
This pin indicates signal quality status on the fiber-optic
link in 100BASE-FX mode. When the signal quality is
good, the SDI+ pin should be driven high relative to the
SDI- pin. 100BASE-FX is disabled when both pins are
simultaneously pulled low. SDI- can also be used for
Signal Detect Common Mode Voltage input.
When in test mode, SDI+, SDI-, FXR+, and FXR- pins
are used as TEST[3:0].
FXR+/TEST[2]
Fiber Receive Input
(For Port 3 only)
Analog Input/Output
When Port 3 is configured as FX Channel, FXR± are
ECL level FX receive pins.
When in test mode, SDI±, and FXR± pins are used as
TEST[3:0].
FXR-/TEST[3]
Fiber Receive Input
(For Port 3 only)
Analog Input/Output
When Port 3 is configured as FX Channel, FXR± are
ECL level FX receive pins.
When in test mode, SDI+, SDI-, FXR+, FXR- pins are
used as TEST[3:0].
10
RXD[3:0]_[1:0]
RMII Receive Data for Ports 0 to 3
Output
These pins are the receive data for Port 0:3.
RX_ER[2:0]
RMII Receive Error for Ports 0 to 2
These pins indicate receive errors for the corresponding port. The pin goes HIGH whenever the
corresponding receiver detects a symbol error.
RX_ER[3]/PHYAD_ST
RMII Receive Error for Port 3
Input/Output
PHY Address Shift
This pin indicates receive errors for Port 3. It goes
HIGH when the corresponding receiver detects a
symbol error.
At power up, this pin is used to set the PHY address by
increasing it by 1. If it is HIGH at power up, the PHYAD
of each port is the upper-3 bits and the port number for
the lower-2 bits. If it is LOW, the PHYAD is incremented
by 1. For example, if the pin is HIGH at power-up and
the upper-3 bits are set to 000, the PHYAD of each port
(in binary notation) is 00000, 00001, 00010, 00011 respectively. If the pin is LOW at power-up and the upper3 bits are set to 000, the PHYAD of each port is 00001,
00010, 00011, and 00100, respectively. This allows a
method of avoiding setting an address to 00000, which
could cause problems with some MACs.
CRS_DV[3:0]
Carrier Sense/Data Valid
Input/Output, Pull-Down
The CRS_DV pin is asserted high when media is
non-idle.
Am79C875
MDIO
Management Data I/O
Input/Output, Pull-Down
This pin is a bidirectional data interface used by the
MAC to access management register within the NetPHY™ 4LP device. This pin has an internal pull-down,
therefore, it requires an external pull-up resistor (1.5
KΩ) as specified in IEEE-802.3 section 22.
MDC
Management Data Clock
Input, Pull-Down
This pin is the serial management clock which is used
to clock MDIO data to the MAC.
RST
Reset
Input, Pull-Up
An active low input will force the NetPHY™ 4LP device
to a known reset state. Reset also can be done through
the internal power-on-reset or MII Register 0, bit 15.
INTR
Interrupt
Tri-State
This pin is true whenever the NetPHY™ 4LP device
detects an event flagged as an interrupt. Events to be
flagged are programmed in Register 17. Interrupts are
cleared on Read. The polarity of INTR (active HIGH or
active LOW) is set by Register 16, bit 14. The default is
active LOW, which requires a 10 KΩ pull-up resistor.
LED Port
Note: Consult the LED Port Configuration section for
appropriate pull-up and pull-down resistors.
LEDDPX[0]/FX_DIS
Port [0] Duplex LED
Input/Output, Pull-Up
Low LED indicates full-duplex and high indicates halfduplex.
FX Mode: Pulled low at reset will put Port 3 in
100BASE-FX mode.
LEDACT_LINK[0]
Port [0] Transmit/Receive Activity LED
Output, Pull-Up
LED is output low for approximately 30 ms each time
there is activity. LINK is an active low signal. This signal
should have a 1k–4.7KΩ pull-up resistor.
LEDSPD[0]/TP1_1
Port [0] Speed LED
Input/Output, Pull-Up
LED is output low when operating in 100BASE-X
modes and high when operating in 10BASE-T modes.
TP1_1: Pulled low at reset will select transmit transformer ratio to be 1.25:1. Default is 1:1 transformer.
LEDDPX[1]/PHYAD[4]
Port [1] Duplex LED
Input/Output, Pull-Up
LED low indicates full-duplex and high indicates halfduplex.
PHY Address[4]. This is the first address bit received
in the management frame, and one of three MSBs for
MII management PHY address. The two LSBs, PHYAD
[1:0] are internally wired to four ports: PHYAD
[11]=Port3,..., PHYAD [00] = Port0. The PHYAD will
also determine the scramble seed, this will help to
reduce EMI when there are multiple ports switching at
the same time. To set this pin, use pull-up or pull-down
resistors in the range of 1 KΩ to 4.7 KΩ.
LEDACT_LINK[1]/PHYAD[3]
Port [1] Transmit/Receive Activity LED
Input/Output, Pull-Up
LED is output low for approximately 30 ms each time
there is activity. LINK is an active low signal.
PHY Address[3]. This is the second MSB and one of
three MSB’s for MII management PHY address. To set
this pin, use pull-up or pull-down resistors in the range
of 1 KΩ to 4.7 KΩ.
LEDSPD[1]/PHYAD[2]
Port [1] Speed LED
Input/Output, Pull-Up
LED is output low when operating in 100BASE-X
modes and high when operating in 10BASE-T modes.
PHY Address[2]. This is the third MSB and one of
three MSB’s for MII management PHY address. To set
this pin, use pull-up or pull-down resistors in the range
of 1 KΩ to 4.7 KΩ.
LEDDPX[2]/DPLX
Port [2] Duplex LED
Input/Output, Pull-Up
LED low indicates full-duplex and high indicates halfduplex.
DPLX: Full Duplex Mode Enable. This pin is logically
OR’ed with a full-duplex enable MII control bit to generate an internal full-duplex enable signal. When asserted high, the NetPHY™ 4LP device operates in fullduplex mode as determined through Auto-Negotiation
or software setting. When asserted low, the internal
control bit (Register 0, bit 8) will determine the full-duplex operating mode.
LEDACT_LINK[2]
Port [2] Transmit/Receive Activity LED
Output, Pull-Up
LED is output low for approximately 30 ms each time
there is activity. LINK is an active low signal. This signal
should have a 1k–4.7KΩ pull-up.
LEDSPD[2]/FORCE100
Port [2] Speed LED
Input/Output, Pull-Up
LED is output low when operating in 100BASE-X
modes and high when operating in 10BASE-T modes.
FORCE100: Force 100BASE-X Operation. When this
signal is pulled high and ANEGA is low at reset, all
ports will be forced to 100BASE-TX operation. When
asserted low and ANEGA is low, all ports are forced to
Am79C875
11
10BASE-T operation. When ANEGA is high,
FORCE100 has no effect on operation.
LEDDPX[3]/SCRAM_EN
Port [3] Duplex LED
Input/Output, Pull-Up
LED low indicates full-duplex and high indicates halfduplex.
SCRAM_EN. Scrambler Enable. Pulled low at reset
will bypass the scrambler. Default is scrambler
enabled. This signal should have a 1k–4.7KΩ pull-up
resistor.
Power and Ground
OVDD
Power
These pins are the digital +3.3 V power supply for I/O.
OGND
Ground
Input/Output, Pull-Up
LED is low for approximately 30 ms each time there is
activity. LINK is an active low signal.
CVDD
Power
CGND
Ground
Digital
AVDD
Power
LEDSPD[3]/BURN_IN
Port [3] Speed LED
AGND
Ground
Input/Output, Pull-Up
LED is low when operating in 100BASE-X modes and
high when operating in 10BASE-T modes.
BURN_IN: Burn-In mode. Burn-in mode for reliability
assurance control. This signal should have a 1k–4.7KΩ
pull-up resistor.
Bias
Analog
These pins are the +3.3V power supply for analog
circuit.
Analog
These pins are the ground for analog circuit.
GAVDD
Power
Analog
These pins are the +3.3 V power supply for common
analog circuits.
GAGND
Ground
Analog
Digital
These pins are the digital ground for Core logic.
ANEGA: Auto-Negotiation Ability. Asserted high
means Auto-Negotiation enable while low means manual selection through DPLX, FORCE100. This pin also
is reflected as ANEGA bit, MII Status Register 1, bit 3.
Analog
This pin is the ground for common analog circuits.
To be tied to an external 10-KΩ (1%) resistor which
should be connected to the analog ground at the
other end.
12
Digital
These pins are the digital ground for I/O.
These pins are the digital +3.3 V power supply for the
Core logic.
LEDACT_LINK[3]/ANEGA
Port [3] Transmit/Receive Activity LED
IBREF
Reference Bias Resistor
Digital
Am79C875
FUNCTIONAL DESCRIPTION
Overview
The NetPHY™ 4LP transceiver is a four-port CMOS
device that implements the complete physical layer for
10BASE-T and the Physical Coding Sublayer (PCS),
Physical Medium Attachment (PMA), and Physical Medium Dependent (PMD) functionality for 100BASE-TX.
The NetPHY™ 4LP transceiver implements Auto-Negotiation allowing two devices connected across a link
segment to take maximum advantage of their capabilities. Auto-Negotiation is performed as defined in the
IEEE 802.3u specification.
The RMII standard reduces the pin count by halving the
number of data pins, eliminating pins not used in switch
applications, and using a single global clock. Each port
has an independent RMII.
RMII uses seven pins per port. They are as follows:
Receive Data
RXD[X]_[1:0]
Carrier Sense
CRS_DV[X]
Receive Error
RX_ER[X]
Transmit Data
TXD[X]_[1:0]
Transmit Enable
TX_EN[X]
The NetPHY™ 4LP device communicates with a
switch or MAC device through the Reduced Media Independent Interface (RMII).
Note: [X] refers to the port.
The NetPHY™ 4LP device consists of the following
functional blocks:
RMII Pin Descriptions
■ RMII Functional Blocks
■ 100BASE-X Block including:
— Transmit and Receive State Machines
— 4B/5B Encoder and Decoder
— Stream Cipher Scrambler and Descrambler
— Link Monitor State Machine
— Far End Fault Indication (FEFI) State Machine
— MLT-3 Encoder
— MLT-3 Decoder with adaptive equalization
■ 10BASE-T Block including:
— Manchester Encoder/Decoder
— Jabber
— Receive Polarity Detect
— Waveshaping and Filtering
■ Carrier Integrity Monitor
In RMII mode, REF_CLK must be sourced by a
50-MHz clock signal.
CRS_DV
Carrier Sense/Receive Data Valid
CRS_DV is asserted by the PHY when the receive medium is non-idle. Loss of carrier results in the deassertion of CRS_DV synchronous to the cycle of REF_CLK,
which presents the first di-bit of a nibble onto RXD[1:0]
(i.e., CRS_DV is deasserted only on nibble boundaries). If the PHY has additional bits to be presented on
RXD[1:0] following the initial deassertion of CRS_DV,
the PHY asserts CRS_DV on cycles of REF_CLK
which present the second di-bit of each nibble. The
PHY deasserts CRS_DV on cycles of REF_CLK which
present the first di-bit of the nibble. As a result, starting
on the byte boundaries, CRS_DV toggles at 25 MHz in
100 Mbps mode and 2.5 MHz in 10 Mbps mode when
CRS ends before RX_DV (i.e., the FIFO still has bits to
transfer when the carrier event ends). Therefore, the
MAC can accurately recover RX_DV and CRS. Refer
to Figure 1.
During a false carrier event, CRS_DV remains asserted for the duration of carrier activity. Refer to
Figure 2.
■ Auto-Negotiation
■ Status LEDs
■ PHY Control and Management
Modes of Operation
The RMII interface provides the data path connection
between the NetPHY™ 4LP transceivers and the
Media Access Controller (MAC), repeater, or switch devices. The MDC and MDIO pins are responsible for
communication between the NetPHY™ 4LP transceiver and the station management entity (STA).
The data on RXD[1:0] is considered valid once
CRS_DV is asserted. However, since the assertion of
CRS_DV is asynchronous relative to REF_CLK, the
data on RXD[1:0] is “00” until proper receive signal
decoding takes place.
Note: CRS_DV is asserted asynchronously in order
to minimize latency of control signals through the PHY.
Am79C875
13
REF_CLK
CRS_DV
RXD[1]
0
0
0
0
0
0
0
0
0
0
0
0
0
1
A
B
C
D
E
F
0
RXD[0]
0
0
0
0
0
0
0
1
1
1
1
1
1
1
A
B
C
D
E
F
0
/J/
/K/
Preamble
SFD
Data
22236G-3
Note: CRS_DV may toggle at 25 MHz starting on a nibble boundary if bits accumulate due to the difference between CRS and RX_DV. The example waveform shows a single nibble accumulated in the FIFO.
Figure 1.
100 Mbps Reception with No Errors
REF_CLK
CRS_DV
RXD[1]
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
RXD[0]
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
22236G-4
False Carrier detected
Figure 2.
100 Mbps Reception with False Carrier
RXD[1:0]
Receive Data [1:0]
RXD[1:0] transitions synchronously to REF_CLK.
Upon assertion of CRS_DV, the PHY will ensure that
RXD[1:0] = 00 until proper receive decoding takes
place. Then 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] in 100 Mbps Mode
For normal reception following assertion of CRS_DV,
RXD[1:0] is “00” until the receiver has determined that
the receive event has a proper Start of Stream Delimiter (SSD), which is a /J/K/ pair. Thereafter, preamble
will appear (RXD[1:0] = 01). Data capture by MACs
occur following detection of SFD.
14
If False Carrier is detected (an event starting with anything other than /J/K/), then RXD[1:0] is”10” until the
end of the receive event. This is a unique pattern since
False Carrier can only occur at the beginning of a
packet where a preamble will be decoded (i.e.,
RXD[1:0]=01).
RXD[1:0] in 10 Mbps Mode
Following assertion of CRS_DV, RXD[1:0] shall be “00”
until the 10BASE-T PHY has recovered clock and is
able to decode the receive data. Once valid receive
data is available from the 10BASE-T PHY, RXD[1:0]
takes on the recovered data values (i.e., starting with
“01” for preamble).
At a REF_CLK frequency of 50 MHz, the value on
RXD[1:0] is valid such that RXD[1:0] may be sampled
every tenth cycle, regardless of the starting cycle within
the group and yield the correct frame data.
Am79C875
TXD[1:0]
Transmit Data
TXD[1:0] in 10 Mbps Mode
TXD[1:0] transitions synchronously with respect to
REF_CLK. When TX_EN is asserted, TXD[1:0] is accepted for transmission by the PHY. TXD[1:0] is
ignored by the PHY while TX_EN is deasserted.
As the REF_CLK frequency is ten times the data rate
in 10 Mbps mode, the value on TXD[1:0] is valid such
that TXD[1:0] may be sampled every tenth cycle, regardless of the starting cycle within the group and yield
the correct frame data.
TXD[1:0] in 100 Mbps Mode
Bit Ordering
TXD[1:0] provides valid data for each REF_CLK period
while TX_EN is asserted. Refer to Figure 3.
Transmission and reception of each octet is done a dibit at a time with the order of di-bit transmission and
reception as shown in Figure 4.
REF_CLK
TX_EN
TXD[1]
0
0
0
0
0
0
0
0
0
0
0
0
0
1
A
B
C
D
E
F
0
TXD[0]
0
1
1
1
1
1
1
1
1
1
1
1
1
1
A
B
C
D
E
F
0
Preamble
SFD
Figure 3.
Data
22236G-5
100 Mbps Transmission
First Bit
MAC's Serial Bit Stream
D0
D1
D2
D3
First
Nibble
Di-Bit
Stream
TXD[0]/RXD[0]
TXD[1]/RXD[1]
D4
D5
D6
D7
Second
Nibble
LSB D0
MSB D1
22236G-6
Figure 4.
100BASE-X Block
The functions performed by the device include encoding of MII 4-bit data (4B/5B), decoding of received code
groups (5B/4B), generating carrier sense and collision
detect indications, serialization of code groups for
transmission, de-serialization of serial data from reception, mapping of transmit, receive, and carrier sense at
the RMII interface, and recovery of clock from the incoming data stream. It offers stream cipher scrambling
and descrambling capability for 100BASE-TX applications.
I n t h e t r a n s m i t d a t a pa t h f o r 1 0 0 M b p s , t h e
NetPHY™ 4LP transceiver receives 2-bit wide data
across the RMII at 50 million di-bits per second. For
100BASE-TX applications, it encodes and
Bit Ordering
scrambles the data, serializes it, and transmits an
MLT-3 data stream to the media via an isolation transformer. For 100BASE-FX applications, it encodes and
serializes the data and transmits a Pseudo-ECL
(PECL) data stream to the fiber optic transmitter.
The NetPHY™ 4LP transceiver receives an MLT-3
data stream from the network for 100BASE-TX. It then
recovers the clock from the data stream, de-serializes
the data stream, and descrambles/decodes the data
stream (5B/4B) before presenting it at the RMII interface.
For 100BASE-FX operation, the NetPHY™ 4LP receives a PECL data stream from the fiber optic transceiver and decodes that data stream. 100BASE-FX
operation is possible only on Port 3.
Am79C875
15
Within the NetPHY™ 4LP device, this block is replicated for each port. The RMII signals should be taken
in context with the port being referred.
The 100BASE-X block consists of the following
sub-blocks:
—
—
—
—
—
—
—
Transmit Process
Receive Process
Internal Loopback Paths
4B/5B Encoder and Decoder
Scrambler/Descrambler
Link Monitor
Far End Fault Generation and Detection &
Code-Group Generator
— MLT-3 encoder/decoder with Adaptive Equalization
— Serializer/Deserializer and Clock Recovery
— Baseline Restoration
Transmit Process
The transmit process generates code-groups based on
the transmit control and data signals on the RMII. This
process is also responsible for frame encapsulation
into a Physical Layer Stream, generating the collision
signal based on whether a carrier is received simultaneously with transmission and generating the Carrier
Sense CRS signal at the RMII. The transmit process is
implemented in compliance with the transmit state diagram as defined in Clause 24 of the IEEE 802.3u specification.
Receive Process
The receive process passes to the RMII a sequence of
data derived from the incoming code-groups. Each
code-group is comprised of five code-bits. This process
detects channel activity and then aligns the incoming
code bits in code-group boundaries for subsequent
data decoding. The receive process is responsible for
code-group alignment and also generates the Carrier
Sense (CRS) signal at the RMII. The receive process
is implemented in compliance with the receive state diagram as defined in Clause 24 of the IEEE 802.3u
specification. The False Carrier Indication as specified
in the standard is also generated by this block, and
communicated to the Reconciliation layer through RXD
and RX_ER.
Encoder/Decoder
The 100 Mbps process in the NetPHY™ 4LP device
uses the 4B/5B encoding scheme as defined in IEEE
802.3, Section 24. This scheme converts between raw
data on the RMII and encoded data on the media pins.
The encoder converts raw data to the 4B/5B code. It
also inserts the stream boundary delimiters (/J/K/ and /
T/R/) at the beginning and end of the data stream as
appropriate. The decoder converts between encoded
data on the media pins and raw data on the RMII. It also
16
detects the stream boundary delimiters to help determine the start and end of packets.
The code-group mapping is defined in Table 1.
Scrambler/Descrambler
The 4B/5B encoded data has repetitive patterns which
result in peaks in the RF spectrum large enough to
keep the system from meeting the standards set by
regulatory agencies such as the FCC. The peaks in the
radiated signal are reduced significantly by scrambling
the transmitted signal. Scramblers add the output of a
random generator to the data signal. The resulting
signal has fewer repetitive data patterns.
After reset, the scrambler seed in each port will be set
to the PHY address value to help improve the EMI
performance of the device.
The scrambled data stream is descrambled, at the receiver, by adding it to the output of another random
generator. The receiver’s random generator has the
same function as the transmitter’s random generator.
The scrambler/descrambler configuration is set by the
SCRAM_EN pin and the EN_SCRM bit (Register 24,
bit 2). The SCRAM_EN pin is latched at the rising edge
of the RST signal. The scrambler/descrambler can be
enabled if SCRAM_EN latches above 2.0 V. Otherwise,
they are all disabled. The EN_SCRM bit sets the
scrambler/descrambler configuration for the corresponding port. The bit defaults to 1 at reset.
The scrambler/descrambler can only be enabled when
the port is in the 100-Mbps MLT-3 mode. The scrambler
is disabled on any port that has a link at 10 Mbps or any
port that is forced to 10 Mbps.
Link Monitor
Signal levels are qualified using squelch detect circuits.
A signal detect (SD) circuit following the equalizer is
asserted high whenever the peak detector detects a
post-equalized signal with peak-to-ground voltage level
larger than 400 mV, which is about 40% of the normal
signal voltage level, and the energy level is sustained
longer than 2 ~ 3 ms. It is deasserted approximately
1 ms to 2 ms after the energy level detected in the receiving lines is consistently less than 300 mV peak.
The signal is forced to low during a local loopback operation (Register 0, bit 14 Loopback is asserted) and
forced to high when a remote Loopback is taking place
(Register 24, bit 3 EN_RPBK is set).
In 100BASE-TX mode, when no signal or invalid signals are detected on the receive pair, the link monitor
will enter in the “link fail” state where only link pulses
will be transmitted. Otherwise, when a valid signal is
detected for a minimum period of time, the link monitor
will then enter link pass state which transmit and
receive functions will be entered.
Am79C875
Table 1.
Code-Group Mapping
MII (TXD[3:0])
Name
PCS Code-Group
Interpretation
0000
0
11110
Data 0
0001
1
01001
Data 1
0010
2
10100
Data 2
0011
3
10101
Data 3
0100
4
01010
Data 4
0101
5
01011
Data 5
0 1 10
6
01110
Data 6
0111
7
01111
Data 7
1000
8
10010
Data 8
1001
9
10011
Data 9
1010
A
10110
Data A
1011
B
10111
Data B
1100
C
11010
Data C
1101
D
11011
Data D
1110
E
11100
Data E
1111
F
11101
Data F
Undefined
I
11111
IDLE; used as inter-Stream fill code
0101
J
11000
Start-of-Stream Delimiter, Part 1 of 2; always used
in pairs with K
0101
K
10001
Start-of-Stream Delimiter, Part 2 of 2; always used
in pairs with J
Undefined
T
01101
End-of-Stream Delimiter, Part 1 of 2; always used in
pairs with R
Undefined
R
00111
End-of-Stream Delimiter, Part 2 of 2; always used in
pairs with T
Undefined
H
00100
Transmit Error; used to force signaling errors
Undefined
V
00000
Invalid Code
Undefined
V
00001
Invalid Code
Undefined
V
00010
Invalid Code
Undefined
V
00011
Invalid Code
Undefined
V
00101
Invalid Code
Undefined
V
00110
Invalid Code
Undefined
V
01000
Invalid Code
Undefined
V
01100
Invalid Code
Undefined
V
10000
Invalid Code
Undefined
V
11001
Invalid Code
In 100BASE-FX mode, the external fiber-optic receiver
performs the signal energy detection function and communicates this information directly to the NetPHY™
4LP device through SDI± pins.
In 10BASE-T mode, a link-pulse detection circuit will
constantly monitor the RX± pins for the presence of
valid link pulses.
10BASE-T Block
The NetPHY™ 4LP transceiver incorporates four fully
independent 10BASE-T physical layer functions, including clock recovery (ENDEC), MAUs, and transceiver functions. The NetPHY™ 4LP transceiver
receives 10-Mbps data from the MAC, switch, or repeater across the RMII at 5 million di-bits per second.
It then Manchester encodes the data before transmission to the network.
Am79C875
17
The 10BASE-T block consists of the following
sub-blocks:
—
—
—
—
—
Transmit Function
Receive Function
Interface Status
Jabber Function
Reverse Polarity Detect
Refer to Figure 5 for the 10BASE-T transmit and
receive data paths.
requirements for 10BASE-T receivers as specified in
IEEE 802.3, Section 14.3.1.3. Each receiver has
internal filtering and does not require external filter
modules or common mode chokes.
Signals appearing at the RX± differential input pair are
routed to the internal decoder. The receiver function
meets the propagation delays and jitter requirements
specified by the 10BASE-T Standard. The receiver
squelch level drops to half its threshold value after unsquelch to allow reception of minimum amplitude signals and to mitigate carrier fade in the event of worst
case signal attenuation and crosstalk noise conditions.
Twisted Pair Interface Status
Clock
Data
Manchester
Encoder
Clock
Data
The NetPHY™ 4LP transceiver will power up in the
Link Fail state. The Auto-Negotiation algorithm will
apply to allow it to enter the Link Pass state. In the Link
Pass state, receive activity which passes the pulse
width/amplitude requirements of the RX± inputs cause
the PCS Control block to assert Carrier Sense (CRS)
signal at the MII interface.
Manchester
Decoder
Jabber Function
Loopback
(Register 0)
Figure 5.
Squelch
Circuit
TX Driver
RX Driver
TX±
RX±
22236G-7
10BASE-T Transmit/Receive Data Paths
Twisted Pair Transmit Function
Data transmission over the 10BASE-T medium requires use of the integrated 10BASE-T MAU and uses
the differential driver circuitry on the TX± pins.
TX± is a differential twisted-pair driver. When properly
terminated, TX± meets the transmitter electrical requirements for 10BASE-T transmitters as specified in
IEEE 802.3, Section 14.3.1.2. The load is a twisted pair
cable that meets IEEE 802.3, Section 14.4.
The TX± signal is filtered on the chip to reduce harmonic content per Section 14.3.2.1 (10BASE-T). Since
filtering is performed in silicon, TX± can be connected
directly to a standard transformer. External filtering
modules are not needed.
Twisted Pair Receive Function
RX+ ports are differential twisted-pair receivers. When
properly terminated, each RX+ port meets the electrical
18
The Jabber function inhibits the 10BASE-T twisted pair
transmit function of the NetPHY™ 4LP transceiver device if the TX± circuits are active for an excessive period (20-150 ms). This prevents one port from
disrupting the network due to a stuck-on or faulty transmitter condition. If the maximum transmit time is exceeded, the data path through the 10BASE-T
transmitter circuitry is disabled (although Link Test
pulses will continue to be sent). The PCS Control block
also sets the Jabber Detect bit in Register 1. Once the
internal transmit data stream from the MENDEC stops,
an unjab time of 250-750 ms will elapse before this
block causes the PCS Control block to re-enable the
transmit circuitry.
When jabber is detected, this block allows the PCS
Control block to assert or de-assert the CRS pin to indicate the current state of the RX± pair. If there is RX±
activity, this block causes the PCS Control block to assert CRS at the RMII. The Jabber function can be disabled by setting Register 24, bit 12.
Reverse Polarity Detect and Correction
Proper 10BASE-T receiver operation requires that the
differential input signal be the correct polarity. That is,
the RX+ line is connected to the RX+ input pin, and the
RX- line is connected to the RX- input pin. Improper
setup of the external wiring can cause the polarity to be
reversed. The NetPHY™ 4LP receivers have the ability
to detect the polarity of the incoming signal and compensate for it. Thus, the proper signal will appear on the
MDI regardless of the polarity of the input signals.
The internal polarity detection and correction circuitry is
set during the reception of the normal link pulses (NLP)
or packets. The receiver detects the polarity of the input
Am79C875
signal on the first NLP. It locks the polarity correction
circuitry after the reception of two consecutive packets.
The state of the polarity correction circuitry is locked as
long as link is established. This function is only available in 10BASE-T mode.
1
Far-End Fault Indication (FEFI)
0
1
0
1
0
1
8 ns
Auto-Negotiation provides a remote fault capability for
detecting an asymmetric link failure. Since
100BASE-FX systems do not use Auto-Negotiation, an
alternative, in-band signaling scheme is used to signal
remote fault conditions. This scheme, Far End Fault Indication, relies on the characteristics of the quiescent
state, a continuous IDLE stream. The IDLE stream is a
continuous stream of logic ones followed by one logic
zero, with the pattern repeated at least 3 times.
A Far-End Fault will be signaled under the following
three conditions: (1) When no activity is received from
the link partner, since this can indicate a broken receive
wire, (2) When the clock recovery circuit detects a
receive signal error or PLL lock error, (3) When management entity sets the transmit Far-end fault bit
(Register 24, bit 7).
The Far-End fault mechanism defaults to enabled in
100BASE-FX mode and disabled in 100BASE-TX and
10BASE-T modes, and may be controlled by software
after reset.
MLT-3
This block is responsible for converting the NRZI data
stream from the PDX block to the MLT-3 encoded data
stream. The effect of MLT-3 is the reduction of energy
on the copper media (TX or FX cable) in the critical
frequency range of 1 MHz to 100 MHz. The receive
section of this block is responsible for equalizing and
amplifying the received data stream and link detection.
The adaptive equalizer compensates for the amplitude
and phase distortion due to the cable.
MLT-3 is a tri-level signal. All transitions are between
0 V and +1 V or 0 V and -1 V. A transition has a logical
value of 1 and a lack of a transition has a logical value
of 0. The benefit of MLT-3 is that it reduces the maximum frequency over the data line. The bit rate of TX
data is 125 Mbps. The maximum frequency (using
NRZI) is half of 62.5 MHz. MLT-3 reduces the maximum frequency to 31.25 MHz.
A data signal stream following MLT-3 rules is illustrated
in Figure 6. The data stream is 1010101.
MLT-3
22236G-8
Figure 6.
MLT-3 Waveform
The TX± drivers convert the NRZI serial output to
MLT-3 format. The RX± receivers convert the received
MLT-3 signals to NRZI. The transmit and receive signals will be compliant with IEEE 802.3u, Section 25.
The required signals (MLT-3) are described in detail in
ANSI X3.263:1995 TP-PMD Revision 2.2 (1995).
The NetPHY™ 4LP device provides on-chip filtering.
External filters are not required for either the transmit or
receive signals.
The TX± pins can be connected to the media via either
a 1:1 transformer or a 1.25:1 transformer. The 1.25:1
ratio provides a 20% transmit power savings over the
1:1 ratio. Refer to Figure 7.
Adaptive Equalizer
The NetPHY™ 4LP device is designed for the maximum of 140 meter UTP-5 cable. A 140-meter UTP-5
cable attenuates the signal by 32 dB at 100 MHz which
far exceed the cable plant attenuation (24-26 dB) defined by TP-PMD.
The amplitude and phase distortion from cable causes
inter-symbol interference (ISI) which makes clock and
data recovery impossible. Adaptive equalization is
done by closely matching the characteristics of the
twisted-pair cable. This is a variable equalizer which
changes equalizer frequency response in accordance
with cable length. The cable length is estimated based
on comparisons of incoming signal strength against
some known cable characteristics. The equalizer tunes
itself automatically to the any cable length to compensate for the amplitude and phase distortion incurred
from the cable.
Baseline Wander Compensation
The 100BASE-TX data stream is not always DC balanced. The media, with transformer and common
Am79C875
19
mode filtering blocks the DC component of the code
and the DC offset of the differential receive input can
wander. The shift in the signal levels causes increase
in error rates. A DC restoration circuit is needed to
compensate for the attenuation of DC components.
The NetPHY™ 4LP device implemented a patentpending DC restoration circuit which, unlike the traditional implementation, does not need the feedback
information from the slicer and clock recovery. The
baseline wander correction circuit is not required and,
therefore, is bypassed when the port is 10BASE-T.
When initial lock is achieved, the APLL switches to
lock-to-data stream, extracts a 125-MHz clock. The recovered 125 MHz clock is also used to generate the 25MHz RX_CLK. The APLL requires no external components for its operation and has high noise immunity and
low jitter. It provides fast phase align (lock) to data in
one transition and its data/clock acquisition time after
power-on is less than 60 transitions.
The APLL can maintain lock on run-lengths of up to 60
data bits in the absence of signal transitions. When no
valid data is present, the APLL switches back to lock
with the TX_CLK, providing a continuously running
RX_CLK.
Clock/Data Recovery
The equalized MLT-3 signal is converted into NRZI format. The NetPHY™ 4LP device uses an analog phase
locked loop (APLL) to extract clock information of the
incoming NRZI data which is used to re-time the data
stream and set data boundaries. The receive clocks
are locked to the incoming data streams. PPM should
be between 50 and 100.
The recovered data is converted from NRZI-to-NRZ
and then to a 5-bit parallel format. The 5-bit parallel
data is not necessarily aligned to 4B/5B code-group’s
symbol boundary. The data is presented to PCS at receive data register output, gated by the 25-MHz
RX_CLK.
VDD
(Note 3)
Isolation
Transformer with
common-mode
chokes
(Note 3)
*
TX+
RJ45
Connector
(8)
(7)
TX+ (1)
1:1 or 1.25:1 *
(5)
(4)
TX–
TX– (2)
0.1 µF
1 kΩ
SDI/MLT3EN
75 Ω
*
1:1
75 Ω
75 Ω
*
RX+
RX+ (3)
50 Ω (Note 4)
50 Ω (Note 4)
RX–
RX– (6)
0.1 µF
75 Ω
470 pF
0.1 µF
(chassis ground)
470 pF
(chassis ground)
Notes:
2. The isolation transformers include common-mode chokes.
3. Consult magnetics vendors for appropriate termination schemes.
4. 50 Ω if a 1:1 isolation transformer is used or 78 Ω if a 1.25:1 isolation transformer is used.
5. 50 (49.9) Ω is normal, but 54.9 Ω can be used for extended cable length operation.
Figure 7.
20
TX± and RX± Termination for 100BASE-TX and 10BASE-T
Am79C875
22236G-9
Auto-Negotiation and Miscellaneous
Functions
by writing to Register 0, bit 14 (LPBK). Remote loopback can be achieved by writing to Register 24, bit 3.
Auto-Negotiation
The local loopback routes transmitted data at the output of the NRZ-to-NRZI conversion module back to the
receiving path’s clock and data recovery module for
connection to PCS in 5-bit symbol format. This loopback is used to check all the device’s connection at the
5-bit symbol bus side and the operation of the analog
phase locked loop. In the local loopback mode, the SDI
output is forced to high and the TX± outputs are
tri-stated.
The object of the Auto-Negotiation function is to determine the abilities of the devices sharing a link. After exchanging abilities, the NetPHY™ 4LP device and
remote link partner device acknowledge each other
and make a choice of which advertised abilities to support. The Auto-Negotiation function facilitates an ordered resolution between exchanged abilities. This
exchange allows both devices at either end of the link
to take maximum advantage of their respective shared
abilities.
The NetPHY™ 4LP device implements the transmit
and receive Auto-Negotiation algorithm as defined in
IEEE 802.3u, Section 28. The Auto-Negotiation algorithm uses a burst of link pulses called Fast Link Pulses
(FLP). The burst of link pulses are spaced between 55
and 140 µs so as to be ignored by the standard
10BASE-T algorithm. The FLP burst conveys information about the abilities of the sending device. The
receiver can accept and decode an FLP burst to learn
the abilities of the sending device. The link pulses
transmitted conform to the standard 10BASE-T template. The NetPHY™ 4LP device can perform autonegotiation with reverse polarity link pulses. The
NetPHY™ 4LP device supports Next Page advertisement.
The NetPHY™ 4LP device uses the Auto-Negotiation
algorithm to select the type connection to be established according to the following priority: 100BASE-TX
full duplex, 100BASE-T4, 100BASE-TX half-duplex,
10BASE-T full duplex, 10BASE-T half-duplex. The
device does not support 100BASE-T4 connections.
The Auto-Negotiation algorithm is initiated when one or
the following events occurs: Auto-Negotiation enable
bit is set, or reset, or soft reset, or transition to link fail
state (when Auto-Negotiation enable bit is set), or
Auto-Negotiation restart bit is set. The result of the
Auto- Negotiation process can be read from the status register for the port of interest (Diagnostic Register,
Register 18).
The NetPHY™ 4LP device supports Parallel Detection
for remote legacy devices that do not support the AutoNegotiation algorithm. In the case that a 100BASE-TX
only device is connected to the remote end, the NetPHY™ 4LP device will see scrambled idle symbols and
establish a 100BASE-TX only connection. If NLPs are
seen, the NetPHY™ 4LP device will establish a
10BASE-T connection.
Loopback Operation
A local loopback and a remote loopback are provided
for diagnostic testing. Local loopback can be achieved
The remote loopback routes receiving data at the output of the clock and data recovery module to the transmitting path’s NRZI-to-MLT-3 conversion module. This
loopback is used to check the device’s connection on
the media side and the operation of its internal adaptive
equalizer, digital phase locked loop, and digital wave
shape synthesizer. During the remote loopback mode,
the SDI output is forced to low.
Power Savings Mechanisms
The NetPHY™ 4LP device has three mechanisms for
reducing power: Selectable 1.25:1 transmit transformer
ratio, Unplugged, and Power Down.
Selectable Transformer
The TX outputs can drive either a 1:1 transformer or a
1.25:1 transformer. The latter can be used to reduce
transmit power further. The TP1_1 pin must be pulled
low at reset to select 1.25:1 transformers. The current
at the TX± pins for a 1:1 ratio transformer is 40 mA for
MLT-3 and 100 mA for 10BASE-T. Using the 1.25:1
ratio reduces the current to 32 mA for MLT-3 and 80 mA
for 10BASE-T.
The cost of using the 1.25:1 option is in impedance
coupling. The reflected capacitance is increased by the
square of the ratio of windings (1.252 = 1.56). Thus, the
reflected capacitance on the media side is roughly
1½ times the capacitance on the board. Extra care in
the layout to control capacitance on the board is required.
Unplugged
The Unplugged feature reduces power consumption
whenever the PHY is operating. The TX output drivers
limit the drive capability if the corresponding receivers
do not detect a link partner within 4 seconds. This prevents “wasted” power. If the receiver detects the absence of a link partner, the corresponding transmitter is
limited to transmitting normal link pulses. Any energy
detected by the receiver enables full transmit capabilities. A typical situation encountered is that most unused ports still consume power. Up to 25% of repeater
and switch ports are unconnected to allow room for future expansion. With NetPHY™ 4LP, unconnected
ports have their receiver disabled until energy is detected. The power savings is most notable on uncon-
Am79C875
21
nected ports and ports running at 10 or 100 Mbps with
Auto-Negotiation disabled. Typical power becomes
100 mW per port.
Power Down
Most of the NetPHY™ 4LP device can be disabled via
the Power Down bit in Register 0, bit 11. Setting this bit
on Register 0 of any port will power down the respective port with the exception of the MDIO/MDC management circuitry. Typical power becomes 5 mW or lower
per port.
LED Port Configuration
The NetPHY™ 4LP device has several pins that are
used for both device configuration and LED drivers.
These pins set the configuration of the device on the
rising edge of RST and thereafter indicate the state of
the respective port. See Table 2.
Table 2.
The polarity of the LED drivers (Active-LOW or ActiveHIGH) is set at the rising edge of RST. If the pin is LOW
at the rising edge of RST, it becomes an active-HIGH
driver. If it is HIGH at the rising edge of RST, it becomes
an active-LOW driver.
Proper configuration requires external pull-up or pulldown resistors. If the LED corresponding to a pin is not
used, the pin must be terminated via a resistor. The resistor value is not critical and can be in the range of
1 KΩ to 4.7 KΩ. If the corresponding LED is used, the
terminating resistor must be placed in parallel with the
LED. Figure 8 illustrates the wiring of the LEDs for both
configuration settings.
The value of the series resistor (RL) should be selected
to ensure sufficient illumination of the LED. It is
dependent on the rating of the LED.
LED Display Configuration
LEDACT_LINK[N]
LEDSPD[N]
LEDDPX[N]
Cable Connected (Link)
LED On
LED Off
LED Off
100Mbps, Half Duplex
LED On
LED On
LED Off
100Mbps, Full Duplex
LED On
LED On
LED On
10Mbps, Half Duplex
LED On
LED Off
LED Off
10Mbps, Full Duplex
LED On
LED Off
LED On
RMII mode: Activity
Blinks on Transmit/Receive Activity
X
X
Notes:
1. N = PHY port number (0...3)
2. X = don’t care
VDD
LEDXXX/XXX
RL
1 - 4.7 kΩ
1 - 4.7 kΩ
RL
LEDXXX/XXX
Configure HIGH with an
Active-LOW LED
Configure LOW with an
Active-HIGH LED
Note: LEDXXX/XXX = any LED pin.
Figure 8.
22
LED Port Configuration
Am79C875
22236G-10
PHY Control and Management Block
(PCM Block)
Register Administration for 100BASE-X PHY
Device
The management interface specified in Clause 22 of
the IEEE 802.3u standard provides for a simple two
wire, serial interface to connect a management entity
and a managed PHY for the purpose of controlling the
PHY and gathering status information. The two lines
are Management Data Input/Output (MDIO) and
Table 3.
Management Data Clock (MDC). A station management entity which is attached to multiple PHY entities
must have prior knowledge of the appropriate PHY address for each PHY entity.
Description of the Methodology
The management interface physically transports management information across the RMII. The information
is encapsulated in a frame format as specified in
Clause 22 of IEEE 802.3u draft standard and is shown
in Table 3.
Clause 22 Management Frame Format
PRE
ST
OP
PHYAD
REGADD
TA
DATA
IDLE
READ
1.1
01
10
AAAAA
RRRRR
Z0
D...........D
Z
WRITE
1.1
01
01
AAAAA
RRRRR
10
D...........D
Z
The PHYAD field, which is five bits wide, allows 32
unique PHY addresses. The managed PHY layer device that is connected to a station management entity
via the MII interface has to respond to transactions
addressed to the PHY's address. A station management entity attached to multiple PHYs, such as in a
managed 802.3 Repeater or Ethernet switch, is required to have prior knowledge of the appropriate PHY
address.
Section 22 of the IEEE 802.3 standard states that all
PHY devices connected to a mechanical interface will
respond to PHYAD “00000” command regardless of
the actual address of the PHY. There are applications
where it is necessary to avoid setting the PHYAD of a
port to “00000.” The NetPHY™ 4LP contains a mechanism that allows the PHYADs to be shifted by 1. The
PHYAD_ST pin enables this mechanism. If the pin is
LOW at power-up, the PHYADs are incremented by 1.
To set the PHYAD pins, use pull-up or pull-down resistors in the range of 1 KΩ to 4.7 KΩ.
Setting the PHYAD Bits
If PHYAD is set to 000, the address of each port is as
follows:
The PHYAD of each port is the combination of the setting of the NetPHY™ 4LP device and the port number.
The NetPHY™ 4LP device is set by PHYAD[4:2] at the
rising edge of RST. The lower two bits of the PHYAD
are set by the individual ports in the PHY. If the
PHYAD[4:2] is set to 010, the PHYAD of each port is as
follows:
Port 0
00001
Port 1
00010
Port 2
00011
Port 3
00100
The address shifting carries over the entire address
space. If PHYAD[4:2] is set to 111, the PHYAD for each
port is as follows:
Port 0
Port 1
Port 2
Port 3
Port 0
Port 1
Port 2
Port 3
01000
01001
01010
01011
Table 4.
11101
11110
11111
00000
PHY Address Setting Frame Structure
PRE
ST
OP
PHYAD
REGADD
TA
DATA
IDLE
READ
1.1
01
10
00000
RRRRR
Z0
XXXXXXXXXPPAAAAA
Z
WRITE
1.1
01
01
00000
RRRRR
10
XXXXXXXXXPPAAAAA
Z
Am79C875
23
MDC
z
MDIO z
(STA)
MDIO
(PHY)
z
z
0
Idle
1
1
Start
0
1
Opcode
(Read)
0
1
1
0
0
PHY Address
16h, Port 2
0
0
0
z
1
0
z
0
1
1
0
0
0
0
TA
Register Address
MII Status, 1h
0
0
1
0
0
0
0
0
1
z
Register Data
Idle
Read Operation
MDC
MDIO z
(STA)
z
z
Idle
0
1
Start
0
1
Opcode
(Write)
1
0
1
1
PHY Address
16h, Port 2
0
0
0
0
0
Register Address
MII Control, 0h
0
1
0
0
1
1
0
0
0
0
TA
1
0
0
0
0
0
0
0
0
Register Data
z
Idle
22236G-11
Write Operation
Figure 9.
PHY Management Read and Write Operations
Bad Management Frame Handling
Table 5.
The management block of the device can recognize
management frames without preambles (preamble
suppression). However, if it receives a bad management frame, it will go into a Bad Management Frame
state. It will stay in this state and will not respond to any
management frame without preambles until a frame
with a full 32-bit preamble is received, then it will return
to normal operation.
Register
Address (in
decimal)
A bad management frame is a frame that does not
comply with the IEEE standard specification. It can be
one with less than 32-bit preamble, with illegal OP field,
etc. However, a frame with more than 32 preamble bits
is considered to be a good frame.
MII Management Control Register
1
MII Management Status Register
2
PHY Identifier 1 Register
3
PHY Identifier 2 Register
4
Auto-Negotiation Advertisement Register
5
Auto-Negotiation Link Partner Ability
Register
6
Auto-Negotiation Expansion Register
7
Next Page Advertisement Register
Reserved
16
Miscellaneous Features Register
17
Interrupt Control/Status Register
18
Diagnostic Register
19
Test Register
20
Miscellaneous Features 2
21
Receiver Error Counter
22
Reserved
23
Reserved
24
Mode Control Register
25-31
Am79C875
Description
0
8-15
24
NetPHY™ 4LP MII Management
Register Set
Reserved
The Physical Address of the PHY is set using the pins
defined as PHYAD[4:2]. These input signals are
strapped externally and sampled as reset is negated.
The PHYAD[1:0] will be decoded by the NetPHY™ 4LP
device to address its internal four PHY channels.
All registers are available on a per port basis.
Table 6.
Legend for Register Tables
Type
Description
RW
Readable and writable
SC
Self Clearing
LL
Latch low until clear
RO
Read Only
RC
Cleared on the read operation
LH
Latch high until clear
Am79C875
25
MII Management Control Register (Register 0)
Table 7.
Reg
Bit
Name
0
15
Reset
MII Management Control Register (Register 0)
Description
Read/
Write
Default
RW/SC
0
RW
0
RW
Set by
FORCE100
pin
RW
Set by
ANEGA pin
RW
0
RW
0
RW/SC
0
RW
Set by
DPLX pin
RW
0
RW
0
1 = PHY reset.
0 = Normal operation.
This bit is self-clearing.
0
14
Loopback
1 = Enable loopback mode. This will loopback TXD to RXD,
thus it will ignore all the activity on the cable media.
0 = Disable loopback mode. Normal operation.
0
13
Speed Select
0
12
Auto-Neg Enable
0
11
Power Down
1 = 100 Mbps.
0 = 10 Mbps.
1 = Enable Auto-Negotiation process (overrides 0.13 and 0.8).
0 = Disable Auto-Negotiation process.
1 = Power down. The NetPHY™ 4LP device will shut off all
blocks except for MDIO/MDC interface.
0 = Normal operation.
0
10
Isolate
1 = Electrically isolate the PHY from MII. However, PHY is still
able to respond to MDC/MDIO.
0 = Normal operation.
0
9
Restart
Auto-Negotiation
1 = Restart Auto-Negotiation process.
0 = Normal operation.
1 = Full duplex.
0 = Half duplex.
0
8
Duplex Mode
Auto-Negotiation enabled: This bit is writable but will be
ignored.
Auto-Negotiation disabled: This pin is reset read value of
DPLX.
0
7
Collision Test
1 = Enable collision test, which issues the COL signal in
response to the assertion of TX_EN signal. Collision test is
enabled regardless of the duplex mode.
0 = disable COL test.
0
26
6:0
Reserved
Write as 0, ignore on read.
Am79C875
MII Management Status Register (Register 1)
Table 8.
MII Management Status Register (Register 1)
Read/
Write
Default
RO
0
100BASE-TX Full 1 = 100BASE-TX with full duplex.
Duplex
0 = No 100BASE-TX full duplex ability.
RO
Set by
DPLX pin
100BASE-TX Half 1 = 100BASE-TX with half duplex.
Duplex
0 = No 100BASE-TX half-duplex ability.
RO
1
RO
Set by
DPLX pin
RO
1
Ignore when read.
RO
0
1 = PHY can accept management (mgmt) frames with or
without preamble.
RO
1
RO
0
RO/LH
0
RO
Set by
ANEGA pin
RO/LL
0
RO/LH
0
RO
1
Reg
Bit
Name
1
15
100BASE-T4
1
14
1
13
1
12
10BASE-T Full
Duplex
1 = 10BASE-T with full duplex.
1
11
10BASE-T Half
Duplex
1 = 10BASE-T with half duplex.
1
10:7
Reserved
1
6
MF Preamble
Suppression
1
5
Auto-Negotiation
Complete
Description
1 = 100BASE-T4 able.
0 = Not 100BASE-T4.
0 = No 10BASE-T full duplex ability.
0 = No 10BASE-T half duplex ability.
0 = PHY can only accept mgmt frames with preamble.
1 = Auto-Negotiation process completed. Registers 4, 5, 6
are valid after this bit is set.
0 = Auto-Negotiation process not completed.
1 = Remote fault condition detected.
1
4
Remote Fault
1
3
Auto-Negotiation
Ability
1
2
Link Status
0 = No remote fault.
This bit will remain set until it is cleared by reading register
1 via management interface.
1 = Able to perform Auto-Negotiation function, its value is
determined by ANEGA pin.
0 = Unable to perform Auto-Negotiation function.
1 = Link is established, however, if the NetPHY™ 4LP
device link fails, this bit will be cleared and remain cleared
until register is read via management interface.
0 = Link is down.
1
1
Jabber Detect
1
0
Extended
Capability
1 = Jabber condition detect.
0 = No Jabber condition detected.
1 = Extended register capable. This bit is tied permanently
to one.
Am79C875
27
PHY Identifier 1 Register (Register 2)
Table 9.
Reg
2
Bit
15:0
Name
PHY Identifier 1 Register (Register 2)
Read/
Write
Default
RO
0022(H)
Read/
Write
Default
Assigned to the 19th through 24th bits of the OUI.
RO
010101
Six bit manufacturer’s model number.
RO
010100
Four bit manufacturer’s revision number. 0001 stands for
Rev. A, etc.
RO
0001
Read/
Write
Default
RW
0
RO
0
RW
0
RW
0
RW
0
RO
0
RW
Set by
DPLX pin
RW
1
RW
Set by
DPLX pin
RW
1
RO
00001
Description
Composed of the 3rd through 18th bits of the Organizationally
Unique Identifier (OUI), respectively.
OUI
PHY Identifier 2 Register (Register 3)
Table 10.
Reg
Bit
Name
3
15:10
OUI
3
9:4
Model Number
3
3:0
Revision Number
PHY Identifier 2 Register (Register 3)
Description
Auto-Negotiation Advertisement Register (Register 4)
Table 11.
Reg
Bit
Name
4
15
Next Page
4
14
Acknowledge
4
13
Remote Fault
4
12:11
Reserved
Auto-Negotiation Advertisement Register (Register 4)
Description
1 = Next Page enabled.
0 = Next Page disabled.
This bit will be set internally after receiving 3 consecutive and
consistent FLP bursts.
1 = Remote fault supported.
0 = No remote fault.
Write as 0, ignore when read.
Full Duplex Flow Control.
4
10
FDFC
1 = Advertise that the DTE(MAC) has implemented both the
optional MAC control sublayer and the pause function as
specified in clause 31 and annex 31 B of 802.3u.
0 = No MAC-based full duplex flow control.
4
9
100BASE-T4
4
8
100BASE-TX
Full Duplex
4
4
4
4
28
7
6
5
4:0
100BASE-TX
Half Duplex
10BASE-T
Full Duplex
10BASE-T
Half Duplex
Selector Field
The NetPHY™ 4LP device does not support 100BASE-T4
function, i.e., this bit ties to zero.
1 = 100BASE-TX with full duplex.
0 = No 100BASE-TX full duplex ability.
Default is set by Register 1.14.
1 = 100BASE-TX with half duplex.
0 = No 100BASE-TX half duplex capability.
Default is set by Register 1.13.
1 = 10 Mbps with full duplex.
0 = No 10Mbps full duplex capability.
Default is set by Register 1.12.
1 = 10 Mbps with half duplex.
0 = No 10 Mbps half duplex capability
Default is set by Register 1.11.
[00001] = IEEE 802.3
Am79C875
Auto-Negotiation Link Partner Ability Register in Base Page Format (Register 5)
Table 12. Auto-Negotiation Link Partner Ability Register in Base Page Format (Register 5)
Reg
Bit
Name
5
15
Next Page
5
14
Acknowledge
5
13
Remote Fault
5
12:11
Reserved
5
10
Flow Control
5
9
100BASE-T4
8
100BASE-TX Full
Duplex
7
100BASE-TX Half
Duplex
6
10BASE-T Full
Duplex
5
5
10BASE-T Half
Duplex
5
4:0
Selector Field
5
5
5
Description
1 = Next Page Requested by Link Partner.
0 = Next Page Not Requested.
1 = Link Partner Acknowledgement.
0 = No Link Partner Acknowledgement.
1 = Link Partner Remote Fault Request.
0 = No Link Partner Remote Fault Request.
Reserved for Future Technology
1 = Link Partner supports Flow Control.
0 = Link Partner does not support Flow Control.
1 = Remote Partner is 100BASE-T4 Capable.
0 = Remote Partner is not 100BASE-T4 Capable.
1 = Link Partner is capable of 100BASE-TX with Full
Duplex.
0 = Link Partner is Not Capable of 100BASE-TX with
Full Duplex
1 = Link Partner is Capable of 100BASE-TX with Half
Duplex.
0 = Link Partner is Not Capable of 100BASE-TX with
Half Duplex
1 = Link Partner is capable of 10BASE-T with Full
Duplex.
0 = Link Partner is Not Capable of 10BASE-T with Full
Duplex
1 = Link Partner is capable of 10BASE-T with Half
Duplex.
0 = Link Partner is Not Capable of 10BASE-T with Half
Duplex.
Link Partner Selector Field.
Read/
Write
Default
RO
0
RO
0
RO
0
RO
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
RO
0
Auto-Negotiation Link Partner Ability Register in Next Page Format (Register 5)
Table 13.
Reg
Bit
Auto-Negotiation LInk Partner Ability Register in Next Page Format (Register 5)
Name
5
15
Next Page
5
14
Acknowledge
5
13
Message Page
5
12
Acknowledge 2
5
11
Toggle
5
10:0
Message Field
Read/
Write
Default
RO
0
RO
0
RO
0
0 = Link Partner cannot Comply with Next Page
Request.
RO
0
Link Partner Toggle.
RO
0
Link Partner’s Message Code.
RO
0
Description
1 = Next Page Requested by Link Partner.
0 = Next Page Not Requested.
1 = Link Partner Acknowledgement.
0 = No Link Partner Acknowledgement.
1 = Link Partner message Page Request.
0 = No Link partner Message Page Request.
1 = Link Partner can Comply with Next Page Request.
Am79C875
29
Auto-Negotiation Expansion Register (Register 6)
Table 14.
Reg
Bit
Name
6
15:5
Reserved
6
4
Auto-Negotiation Expansion Register (Register 6)
Description
Ignore when read.
1 = Fault detected by parallel detection logic, this fault is due
to more than one technology detecting concurrent link up
Parallel Detection condition. This bit can only be cleared by reading this register
Fault
via management interface.
Read/
Write
Default
RO
0
RO/LH
0
RO
0
0 = No fault detected by parallel detection logic.
1 = Link partner support next page function.
6
3
Link Partner Next
Page Able
6
2
Next Page Able
Next page is supported, i.e., this bit is permanently ties to 1.
RO
1
6
1
Page Received
It is set when a new link code word has been received into the
Auto-Negotiation Link Partner Ability Register. This bit is
cleared upon a read of this register.
RO/LH
0
6
0
RO
0
0 = Link partner does not support next page function.
Link Partner Auto- 1 = Link partner is Auto-Negotiation able.
Negotiation Able 0 = Link partner is not Auto-Negotiation able
Auto-Negotiation Next Page Advertisement Register (Register 7)
Table 15.
Reg
Bit
Auto-Negotiation Next page Advertisement Register (Register 7)
Name
Description
Read/
Write
Default
RW
0
RO
0
RW
1
RW
0
RW
0
RW
001
Next page indication:
7
15
NP
1 = Another Next Page desired.
0 = No other Next Page Transfer desired
7
14
Reserved
7
13
MP
Ignore when read.
Message page:
1 = Message page
0 = Un-formatted page.
Acknowledge 2
7
12
ACK2
1 = Will comply with message.
0 = Cannot comply with message.
Toggle:
7
11
TOG_TX
1 = Previous value of transmitted link code word equals to 0
0 = Previous value of transmitted link code word equals to 1
7
10:0
CODE
Message/Un-formatted Code Field.
Reserved Registers (Registers 8-15, 22-23, 25-31)
The NetPHY™ 4LP device contains reserved registers
at addresses 8-15, 22-23, 25-31. These registers
should be ignored when read and should not be written
at any time.
30
Am79C875
Miscellaneous Features Register (Register 16)
Table 16.
Reg
Bit
Name
16
15
Reserved
16
14
INTR_LEVL
16
13
TXJAM
16
12:4
Reserved
16
3:0
Reserved
Miscellaneous Features Register (Register 16)
Read/
Write
Default
RW
0
RW
0
RO
0
Write as 0, ignore when read.
RW
00000
Ignore when read.
RO
0
Description
Write as 0; 1 = factory use only.
1 = INT is forced to 1 to signal an interrupt.
0 = INT is forced to 0 to signal an interrupt.
1 = Force CIM to send jam pattern.
0 = Normal operation mode.
Interrupt Control/Status Register (Register 17)
Table 17.
Interrupt Control/Status Register (Register 17)
Read/
Write
Default
Jabber Interrupt Enable.
RW
0
Receive Error Interrupt Enable.
RW
0
Page_Rx_IE
Page Received Interrupt Enable.
RW
0
12
PD_Fault_IE
Parallel Detection Fault Interrupt Enable.
RW
0
17
11
LP_Ack_IE
Link Partner Acknowledge Interrupt Enable.
RW
0
17
10
Link_Not_OK_ IE
Link Status Not OK Interrupt Enable.
RW
0
17
9
R_Fault_IE
Remote Fault Interrupt Enable.
RW
0
17
8
ANeg_Comp_IE
Auto-Negotiation Complete Interrupt Enable.
RW
0
17
7
Jabber_Int
This bit is set when a jabber event is detected.
RC
0
17
6
Rx_Er_Int
This bit is set when RX_ER transitions high.
RC
0
17
5
Page_Rx_Int
This bit is set when a new page is received from link partner during
Auto-Negotiation.
RC
0
17
4
PD_Fault_Int
This bit is set when parallel detect fault is detected.
RC
0
17
3
LP_Ack_Int
This bit is set when the FLP with acknowledge bit set is received.
RC
0
This bit is set when link status switches from OK status to Non-OK
status (Fail or Ready).
RC
0
This bit is set when remote fault is detected.
RC
0
This bit is set when Auto-Negotiation is complete.
RC
0
Reg
Bit
Name
17
15
Jabber_IE
17
14
Rx_Er_IE
17
13
17
17
2
Link_Not_OK Int
17
1
R_Fault_Int
17
0
A_Neg_Comp Int
Description
Am79C875
31
Diagnostic Register (Register 18)
Table 18.
Read/
Write
Default
Ignore when read.
RO
0
DPLX
This bit indicates the result of the Auto-Negotiation for duplex
arbitration.
1 = Full Duplex.
0 = Half Duplex.
RO
0
Speed
This bit indicates the result of the Auto-Negotiation for data speed
arbitration.
1 = 100 Mbps.
0 = 10 Mbps.
RO
0
RO
0
RO/RC
0
RO
0x22
Reg
Bit
Name
18
15:12
Reserved
18
18
11
10
Diagnostic Register (Register 18)
Description
18
9
RX_PASS
In 10BASE-T mode, a 1 indicates that Manchester data has been
detected.
In 100BASE-TX mode, a 1 indicates a valid signal has been
received but not necessarily locked onto.
18
8
RX_LOCK
1 = Received RLL has locked onto the received signal for selected
data-rate (10BASE-T or 100BASE-TX)
0 = Receive PLL has not locked onto received signal.
This bit remains set until read.
18
7:0
Reserved
Ignore when read.
Test Register (Register 19)
Table 19. Test Register (Register 19)
Read/
Write
Default
Ignore when read, write as Default (0x1000).
RW
0x1000
Reserved
Ignore when read, write as Default (0x0010).
RW
0x0010
Reserved
Ignore when read, write as 0.
RW
0
Selects transformer ratio.
1 = 1.25:1
0 = 1:1
The default value is controlled by the TP1_1 pin.
RW
0
This bit controls internal logic, including power-saving circuitry. For 10
and 100 Mbps transmit compliance testing ONLY, this bit must be
10/100 Mbps
turned off, but should be turned on for normal operation. The default
Transmit
is 1 (on).
Compliance Test
1 = Normal operation.
0 = Compliance test mode.
RW
1
RW
0
Read/
Write
Default
Reg
Bit
Name
19
15:12
Reserved
19
11:8
19
7
19
6
19
5
19
4:0
1.25:1
Reserved
Description
Ignore when read, write as 0.
Miscellaneous Features 2 Register (Register 20)
Table 20.
Miscellaneous Features 2 Register (Register 20)
Reg
Bit
Name
20
15:12
Reserved
Ignore when read, write as Default (0x0110).
RW
0x0110
20
11:8
Reserved
Ignore when read, write as Default (0x1001).
RW
0x1001
These bits are the cable length indicators. Increment from 0000 to
1111, or approximately every 10 meters. The equivalent is 0 to 32dB
with an increment of 2dB @ 100Mhz. The value is read back from the
equalizer, and the measured value is not absolute.
RO
0
Ignore when read.
RO
0x0010
20
7:4
Cable length
indicator
20
3:0
Reserved
32
Description
Am79C875
Receive Error Counter (Register 21)
Table 21.
Reg
Bit
Name
21
15:0
RX_ER Counter
Receive Error Counter (Register 21)
Description
Count of Receive Error Events.
Read/
Write
Default
RW
0000 (hex)
Mode Control Register (Register 24)
Table 22.
Reg
24
Bit
15
Name
SDCM_SEL
Mode Control Register (Register 24)
Description
Select Common Mode Voltage Setting for FX Signal Detect (SDI)
input signal.
1 = Select Internal Common Mode Setting.
Read/
Write
Default
RW
0
RW
0
RW
0
RW
0
RW
0
RW
1
0 = Select External Common Voltage Setting.
24
24
14
13
Force 10BASE-T
Link Up
Force
100BASE-TX
Link Up
24
12
Jabber Disable
24
11
Reserved
10
Activity LED
Configuration
24
1 = Force link up at 10 Mbps without checking NLP. AutoNegotiation must be disabled and the data rate must be 10 Mbps.
0 = Normal Operation.
1 = Force link up at 100 Mbps. Auto-Negotiation must be disabled
and the data rate must be 100 Mbps.
0 = Normal Operation.
1 = Disable Jabber function in PHY.
0 = Enable Jabber function in PHY.
Write as 0, ignore when read.
1 = Activity only responds to receive operation.
0 = Activity responds to Receive and transmit.
In repeater mode, this bit will be ignored.
24
9
Reserved
Write as 0, ignore when read.
RW
0
24
8
FEFI_Disable
Set this bit will disable FEFI generation and detection function. The
default value of this bit is 0 when the chip is working in FX mode.
Otherwise the default value is 1.
RW
Set by
FX_DIS and
ANEGA pins
24
7
Force FEFI
Transmit
This bit is set to force the transmit FEFI pattern.
RW
0
24
6
RX_ER_CNT Full
This bit is set to one to indicate the Receive Error Counter is full.
RO/RC
0
24
5
Disable
RX_ER counter
1 = disable Receive Error Counter.
RW
0
24
4
DIS_WDT
1 = Disable the watchdog timer in the decipher.
RW
0
24
3
EN_RPBK
1 = Enable remote loopback, 0 = Disable remote loopback.
RW
0
RW
Set by
SCRAM_EN
pin
0 = Disable data scrambling.
1 = Enable data scrambling.
24
2
EN_SCRM
When FX_DIS pin is asserted low or FX_SEL bit (Register 24.0) is
set to logic high, this bit will be overwritten as “1” automatically.
The default of this bit is set by power on read value of FX_DIS.
24
1
Reserved
Write as 0, ignore when read.
RO
0
24
0
FX_SEL
Set this bit to logic 1 to select 100BASE-FX mode, set to logic 0 to
select 100BASE-TX.
RW
Set by
FX_DIS
Am79C875
pin
33
ABSOLUTE MAXIMUM RATINGS
Operating Ranges
Storage Temperature . . . . . . . . . . . . .-55°C to +150°C
Commercial (C):
Ambient Temperature Under Bias . . . -55°C to +150°C
Operating Temperature (TA) . . . . . . . . . 0°C to +70°C
Supply Voltage (VDD) . . . . . . . . . . . . . -0.5 V to +5.5 V
Supply Voltage (all VDD) . . . . . . . . . . . . . . +3.3 V ±5%
Voltage Applied to any input pin. . . . . . . -0.5 V to VDD
Stresses above those listed under Absolute Maximum
Ratings may cause permanent device failure.
Functionality at or above these limits is not implied.
Exposure to absolute maximum ratings for extended
periods may affect device reliability.
Supply Voltage (5-V tolerant pins) . . . . . . +5.0 V ±5%
Industrial (I):
Operating Temperature (TA) . . . . . . . . -40°C to +85°C
Supply Voltage (all VDD) . . . . . . . . . . . . . . +3.3 V ±5%
Supply Voltage (5-V tolerant pins) . . . . . . +5.0 V ±5%
Operating ranges define those limits between which
functionality of the device is guaranteed.
DC CHARACTERISTICS
Note: Parametric Values are the same for Commercial and Industrial devices.
Symbol
Parameter Description
Test Conditions
VIL
Input LOW Voltage
VIH
Input HIGH Voltage
VOL
Output LOW Voltage
IOL = 8 mA
VOH
Output HIGH Voltage
IOH = -4 mA
VOLL
Output LOW Voltage (LED)
IOL (LED) = 10 mA
VOHL
Output HIGH Voltage (LED)
IOL (LED) = -10 mA
VCMP
Input Common-Mode Voltage
PECL (Note 1)
VIDIFFP
Differential Input Voltage
PECL (Note 1)
VDD = Maximum
VOHP
Output HIGH Voltage PECL
(Note 4)
VOLP
Minimum
Maximum
Units
0.8
V
2.0
V
0.4
2.4
V
V
0.4
VDD – 0.4
V
V
VDD – 1.5
VDD – 0.7
V
400
1,100
mV
PECL Load
VDD – 1.025
VDD – 0.60
V
Output LOW Voltage PECL
(Note 4)
PECL Load
VDD – 1.81
VDD – 1.62
V
VSDA
Signal Detect Assertion
Threshold Peak-to-Peak
(Note 2)
MLT-3/10BASE-T Test Load
-
1000
mV
VSDD
Signal Detect Deassertion
Threshold Peak-to-Peak
(Note 3)
MLT-3/10BASE-T Test Load
200
-
mV
IIL
Input LOW Current (Note 5)
-40
µA
IIH
Input HIGH Current (Note 5)
VIN = VDD
40
µA
VTXOUT
Differential Output Voltage
(Note 6)
MLT-3/10BASE-T Test Load
950
1050
mV
VTXOS
Differential Output Overshoot
(Note 6)
MLT-3/10BASE-T Test Load
-
0.05 * VTXOUT
V
VTXR
Differential Output Voltage
Ratio (Note 6 & Note 7)
MLT-3/10BASE-T Test Load
0.98
1.02
-
34
VDD = Maximum
VIN = 0.0 V
Am79C875
Symbol
Parameter Description
Test Conditions
Minimum
Maximum
Units
VTSQ
RX± 10BASE-T Squelch
Threshold
Sinusoid 5 MHz<f<10 MHz
300
585
mV
VTHS
RX± Post-Squelch Differential
Sinusoid 5 MHz<f<10 MHz
Threshold 10BASE-T (Note 8)
150
293
mV
VRXDTH
10BASE-T RX± Differential
Switching Threshold (Note 8)
Sinusoid 5 MHz<f<10 MHz
-60
60
mV
VTX10NE
10BASE-T Near-End Peak
Differential Voltage (Note 9)
MLT-3/10BASE-T Test Load
2.2
2.8
V
IOZ
Output Leakage Current
(Note 10)
0.4 V < VOUT < VDD
-30
100
µA
Power Supply Current Consumption
Symbol
Parameter
Description
Test Conditions
Minimum
Typical
Maximum
Units
IDD
Power Supply Current
for 10BASE-T
(Note 11)
VDD = maximum
-
260
(Note 13)
480
(Note 11,12)
mA
IDD
Power Supply Current
for 100BASE-TX/FX
(Note 11)
VDD = maximum
-
300
380
(Note 11)
mA
Notes:
1. Applies to FXR+, FXR-, SDI+, and SDI- inputs only. Valid only when Port 3 is in PECL mode. VDD is that of the fiber
transceiver.
2. Applies to RX± inputs when the corresponding port is in MLT-3 mode only. The RX± input is guaranteed to assert internal
signal detect for any valid peak-to-peak input signal greater than VSDA MAX. Tested within limits of VSDD and VSDA.
3. Applies to RX± inputs when the corresponding port is in MLT-3 mode only. The RX± input is guaranteed to de-assert internal
signal for any peak to peak signal less than VSDD MIN. Tested within limits of VSDD and VSDA.
4. Applies to FXT+ and FXT- outputs only. Valid only when Port 3 is in PECL mode. VDD is that of the fiber transceiver.
5. Applies to digital inputs and all bidirectional pins. RX± limits up to 1.0 mA max for IIL and -1.0 mA min for IIH. Pull-up/pull-down
resistors effect this value.
6. Applies to TX± differential outputs only. Valid only when the port is in the MLT-3 mode.
7. VTXR is the ratio of the magnitude of TX± in the positive direction to the magnitude of TX± in the negative direction.
8. Parameter not tested.
9. Only valid for TX output when the port is in the 10BASE-T mode.
10. IOZ applies to all high-impedance output pins. Pull-up/pull-down resistors effect this value.
11. Tested with all TX± output pins driving the rated load.
12. Assumes 80% Utilization with all ports at 10 Mbps, using 1:1 transformers.
13. Typical is 30% network utilization.
14. Assumes outputs are loaded, and all LEDs are used.
Am79C875
35
SWITCHING WAVEFORMS
Key to Switching Waveforms
WAVEFORM
INPUTS
OUTPUTS
Must be
Steady
Will be
Steady
May
Change
from H to L
Will be
Changing
from H to L
May
Change
from L to H
Will be
Changing
from L to H
Don’t Care,
Any Change
Permitted
Changing,
State
Unknown
Does Not
Apply
Center
Line is HighImpedance
“Off” State
KS000010-PAL
RX±
VSDA
VSDD
SWITCHING WAVEFORMS
22236G-12
Figure 10.
36
MLT-3 Receive Input
Am79C875
VDD
49.9 Ω
49.9 Ω
Isolation
Transformer
• 1:1 •
TX+
100 Ω 2%
TX75 Ω 5%
0.01 µF
0.01 µF
Chassis Ground
Figure 11.
22236G-13
MLT-3 and 10BASE-T Test Load with 1:1 Transformer Ratio
VDD
78.1 Ω
Isolation
Transformer
78.1 Ω
• 1:25:1 •
TX+
100 Ω 2%
TX75 Ω 5%
0.01 µF
0.01 µF
22236G-14
Chassis Ground
Figure 12.
MLT-3 and 10BASE-T Test Load with 1.25:1 Transformer Ratio
VTXOS
+VTXOUT
VTXOUT
TX±
112 ns
22236G-15
-VTXOUT
Figure 13.
Near-End 100BASE-TX Waveform
Am79C875
37
VTX10NE
TX±
10BASE-T
22236G-16
0
Figure 14.
Near-End 10BASE-T Waveform
VDD = 3.3 V
VDD = 5 V
69 Ω
82.5 Ω
Pin
Pin
183 Ω
130 Ω
5 V Test Load
Figure 15.
38
3.3 V Test Load
Recommended PECL Test Loads
Am79C875
22236G-17
SWITCHING CHARACTERISTICS
System Clock Signal
Symbol
Parameter Description
Min.
Max.
Unit
tCLK
REFCLK Period
19.999
20.001
ns
tCLKH
REFCLK Width HIGH
9
11
ns
tCLKL
REFCLK Width LOW
9
11
ns
tCLR
REFCLK Rise Time
-
5
ns
tCLF
REFCLK Fall Time
-
5
ns
Notes:
1. Parametric values are the same for Commercial and Industrial devices.
tCLK
tCLKL
tCLKH
tCLR
tCLF
80%
20%
TX_CLK
Figure 16.
22236G-18
Clock Signal
MLT-3 Signals
Parameter Description
Min.
Max.
Unit
tTXR
Symbol
Rise Time of MLT-3 Signal
3.0
5.0
ns
tTXF
Fall Time of MLT-3 Signal
3.0
5.0
ns
tTXRFS
Rise Time and Fall Time Symmetry of MLT-3 Signal
-
5
%
tTXDCD
Duty Cycle Distortion Peak to Peak
-
0.5
ns
tTXJ
Transmit Jitter Using Scrambled Idle Signals
-
1.4
ns
1
tTXR
0
1
0
1
0
1
tTXF
TX±
16 ns
tXTDCD
Figure 17.
tXTDCD
22236G-19
MLT-3 Test Waveform
Am79C875
39
MII Management Signals
Symbol
Parameter Description
Min.
Max.
Unit
tMDPER
MDC Period
40
ns
tMDWH
MDC Pulse Width HIGH
16
ns
tMDWL
MDC Pulse Width LOW
16
ns
tMDPD
MDIO Delay From Rising Edge of MDC
-
tMDS
MDIO Setup Time to Rising Edge of MDC
4
tMDH
MDIO Hold Time From Rising Edge of MDC
20
ns
ns
3
ns
tMDPER
tMDWH
tMDWL
MDC
tMDPD
MDIO
mdio_tx.vsd
Figure 18.
22236G-20
Management Bus Transmit Timing
MDC
tMDS
tMDH
MDIO
22236G-21
Figure 19.
40
Management Bus Receive Timing
Am79C875
Independent RMII Mode Signals
100 Mbps RMII Transmit
Symbol
Parameter Description
Min.
Max.
Unit
tRS100
TX_EN[X], TXD[X]_[1:0] Setup Time to REFCLK Rising Edge
4
-
ns
tRH100
TX_EN[X], TXD[X]_[1:0] Hold time From REFCLK Rising Edge
2
-
ns
tRTJ100
Transmit Latency TX_EN[X] Sampled by REFCLK to First Bit of /J/
60
100
ns
tTIDLE100
Required De-assertion Time Between Packets
120
-
ns
REFCLK
tRS100
TX_EN[X]
tRS100
tRH100
TXD[X]_[1:0]
tRTJ100
TX±
/J/
22236G-22
Figure 20.
RMII 100 Mbps Transmit Start of Packet
REFCLK
tTIDLE100
TX_EN[X]
TX±
/J/
/T/
22236G-23
Figure 21.
RMII 100 Mbps Transmit End of Packet Timing
Am79C875
41
100 Mbps RMII Receive
Symbol
Parameter Description
Min.
Max.
Unit
tRJC100
CRS_DV[X] HIGH After First Bit of /J/
80
150
ns
tRCR100
RXD[X]_[1:0], CRS_DV[X] Delay After the Rising Edge of
REFCLK
5
13
ns
tRTC100
First Bit of /T/ to CRS_DV[X] LOW
120
190
ns
Note: CRS_DV[X] is asynchronous at the beginning of receive (1st rising edge of REFCLK), but is synchronous at
the end of receive.
RX±
/J/
tRJC100
CRS_DV[X]
REFCLK
tRCR100
RXD[X]_[1:0]
22236G-24
Figure 22.
RX±
100 Mbps RMII Receive Start of Packet Timing
/T/R/
tRTC100
CRS_DV[X]
tRCR100
tRCR100
REFCLK
RXD[X]_[1:0]
22236G-25
Figure 23.
42
100 Mbps RMII Receive End of Packet Timing
Am79C875
10 Mbps RMII Transmit
Symbol
Parameter Description
Min.
Max.
Unit
tRS10
TX_EN[X], TXD[X]_[1:0] Setup Time to REFCLK Rising Edge
4
-
ns
tRH10
TX_EN[X], TXD[X]_[1:0] Hold time From REFCLK Rising Edge
2
-
ns
tRTP10
Transmit Latency TX_EN[X] Sampled by REFCLK to Start of
Packet
240
360
ns
tTIDLE10
Required De-assertion Time Between Packets
300
-
ns
REFCLK
tRS10
TX_EN[X]
tRS10
tRH10
TXD[X]_[1:0]
tRTP10
TX±
22236G-26
Figure 24.
RMII 10 Mbps Transmit Start of Packet
REFCLK
tTIDLE10
TX_EN[X]
t RS10
TX±
22236G-27
Figure 25.
RMII 10 Mbps Transmit End of Packet Timing
Am79C875
43
10 Mbps RMII Receive
Symbol
Parameter Description
Min.
Max.
Unit
tRSPC10
CRS_DV[X] HIGH After Start of Packet
200
350
ns
tRCR10
RXD[X]_[1:0], CRS_DV[x] Delay After the Rising Edge of
REFCLK
5
13
ns
tREPC10
End of Packet to CRS_DV[X] LOW
130
190
ns
RX±
tRSPC10
CRS_DV[X]
REFCLK
tRCR10
RXD[X]_[1:0]
22236G-28
Figure 26.
10 Mbps RMII Receive Start of Packet Timing
RX±
tREPC10
CRS_DV[X]
t RCR10
REFCLK
tRCR10
RXD[X]_[1:0]
22236G-29
Figure 27.
44
10 Mbps RMII Receive End of Packet Timing
Am79C875
PHYSICAL DIMENSIONS*
PQR100 (measured in millimeters)
*For reference only. BSC is an ANSI standard for Basic Space Centering.
Am79C875
45
ERRATA
NetPHY™ 4LP Revision B.4 is the current production revision silicon with errata – please refer to the descriptions
below.
Revision B.4 Errata Summary
The NetPHY™ 4LP device has a total of 5 errata, all of which are minor and should not cause concern. All information below should be used in conjunction with the NetPHY™ 4LP Final Datasheet PID 22236, available on the AMD
web site (www.amd.com).
Errata for NetPHY™ 4LP B.4
The SYMPTOM section gives an external description of the problem. The IMPLICATION section explains how the
device behaves and its impact on the system. The WORKAROUND section describes a workaround for the problem.
The STATUS section indicates when and how the problem will be fixed.
B4.1) 10BASE-T signal acceptance compliance test suite - test #1411.11.03
SYMPTOM:
CRS response to Signal 7a, 7b, 8a, 8b and 10 is unreliable unless the signal is preceded by a
preamble.
IMPLICATION:
These compliance tests reflect boundary conditions unlikely to happen in normal operation.
Some boundary conditions are meant to test the receiver's robustness and if it properly receives
valid data. We have successfully received 10Mbps data for all cable lengths, and we believe
that the chance of failure in the field is extremely low.
WORKAROUND:
There is no external work around.
STATUS:
This errata will not be fixed.
B4.2) 10BASE-T Local Loopback
SYMPTOM:
10BASE-T Local loopback does not work.
IMPLICATION:
This is a minor issue which does not affect normal operation.
WORKAROUND:
Loopback testing must be performed external to the device.
STATUS:
This errata will not be fixed.
B4.3) 10Mb not interrupted by 100Mb data reception
SYMPTOM:
If the PHY is in 10BASE-T and for an unknown reason, 100Mbps data is received, the PHY
should drop 10Mb link and establish 100Mb link.
IMPLICATION:
This is a minor issue which should not affect normal operation. This is UNH test 25.28c, where
it is stated that the standard does not allow for this behavior and that no harm to the network is
anticipated. Additionally, it is not uncommon to find this issue with many PHYs today.
WORKAROUND:
There is no external workaround.
STATUS:
This errata will not be fixed.
B4.4) Delayed idle following abnormal packet transmission
SYMPTOM:
If a packet does not end in a /T/R/, the RX_ER signal does not go true immediately after, and
is delayed 1 to 2 clock cycles. The receiver will then enter the idle state.
IMPLICATION:
This is a minor issue. If the packet does not terminate properly, RX_ER is delayed 1-2 clock
cycles. The issue is believed to be minor since the likelihood of encountering improperly terminated data packets is small. However, it will affect the recording of errors by the system. (UNH
1.24)
WORKAROUND:
There is no external workaround.
STATUS:
This errata will not be fixed.
46
Am79C875
B4.5) Full Duplex operation with Auto-Negotiation Disabled
SYMPTOM:
If Auto-Negotiation is disabled, the device cannot be pin-strapped to full-duplex. LEDDPX[2]/
DPLX (Pin 41) should set the duplex at reset if LEDACT_LINK/ANEGA (Pin 39) is LOW at reset. Instead, all 4 ports are half-duplex regardless of the setting of Pin 41.
IMPLICATION:
This is a minor issue which should not affect normal operation. Auto-Negotiation operation is
usually set by default in systems today so that both link partners can operate at the highest setting (speed and duplex). Very rarely do systems rely on Parallel Detect to set the speed of the
link. Note that RMII operation is by definition, full-duplex.
WORKAROUND:
Full-duplex operation must be set through management pins, Register 0, bit 8.
STATUS:
This errata will not be fixed.
Am79C875
47
REVISION SUMMARY
Revision C to D
1. Register 18, added bits 8 and 9 for user checking.
2. Register 19, added bit 6, Transformer ratio selection via software.
3. Register 20, added bits 7:4, Cable length indicators.
4. Register 24, added bit 5, RX_ER counter disable.
5. DC Characteristics: added VOLL, new IIH, IIL and IOZ maximum values
6. MII Management signals: MDC period changed to 40ns (min), MDC pulse high/low changed to 16ns (min)
7. MII Management signals: MDIO delay changed to 20ns (max), MDIO setup time changed to 4ns (min), MDIO
hold time changed to 3ns (max)
Revision D to E
1. Specified using resistors in the range of 1 KΩ to 4.7 KΩ for setting the PHYAD pins. Figure 8 reflects the correct
resistors.
2. Added bit 10, Flow Control Support, to Register 5.
Revision E to F
1. Added industrial temperature support and new OPN(KI).
2. Minor edits.
Revision F to G
1. Removed CIM_DIS references.
2. Added pull-up resistor requirements for LEDACT_LINK[0] and LEDDPX[2]/DPLX.
3. Changed pull-up resistor values for LEDs to 1–4.7 KΩ.
4. Maximum input voltage is 5.5 V; operating voltage for 5-V-tolerant pins is 5.0 V.
5. Minor edits.
Revision G to H
1. Final version
2. Corrected pull-up resistor value for LEDACT_LINK[2] to 1k–4.7KΩ.
3. Updated package drawing - some tolerances modified.
The contents of this document are provided in connection with Advanced Micro Devices, Inc. (“AMD”) products. AMD makes no representations
or warranties with respect to the accuracy or completeness of the contents of this publication and reserves the right to make changes to specifications and product 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 publication. Except as set forth in AMD's Standard Terms and Conditions of Sale, AMD assumes no
liability whatsoever, and disclaims any express or implied warranty, relating to its products including, but not limited to, the implied warranty of
merchantability, fitness for a particular purpose, or infringement of any intellectual property right.
AMD's products are not designed, intended, authorized or warranted for use as components in systems intended for surgical implant into the
body, or in other applications intended to support or sustain life, or in any other application in which the failure of AMD's product could create a
situation where personal injury, death, or severe property or environmental damage may occur. AMD reserves the right to discontinue or make
changes to its products at any time without notice.
Trademarks
Copyright © 2000, 2001, 2002, 2003 Advanced Micro Devices, Inc. All rights reserved.
AMD, the AMD logo, and combinations thereof are trademarks of Advanced Micro Devices, Inc.
NetPHY is a trademark of Advanced Micro Devices, Inc.
Product names used in this publication are for identification purposes only and may be trademarks of their respective companies.
48
Am79C875