2. General Description .................................................................................................................................................................. 2
5.3 Port4 Related Pins............................................................................................................................................................... 7
5.4 LED Pins............................................................................................................................................................................. 8
5.5 Power Pins .......................................................................................................................................................................... 8
6.2.3 Data Reception........................................................................................................................................................... 10
6.2.4 Data Forwarding......................................................................................................................................................... 10
6.2.5 Flow Control ...............................................................................................................................................................11
6.3.3 10Base-T Receive Function ........................................................................................................................................11
6.3.4 Link Monitor...............................................................................................................................................................11
6.3.6 100Base-TX Receive Function .................................................................................................................................. 12
6.3.7 Power Saving Mode................................................................................................................................................... 12
6.5 MII Port............................................................................................................................................................................. 13
6.5.1 General Description ................................................................................................................................................... 13
6.5.3 MII MAC Mode......................................................................................................................................................... 16
7.1 Absolute Maximum Ratings ............................................................................................................................................. 18
7.2 Operating Range ............................................................................................................................................................... 18
7.3 DC Characteristics (0°C<Ta<60°C, 3.15V<Vcc<3.45V) ................................................................................................. 18
7.4 AC Characteristics (0°C<Ta<60°C, 3.15V<Vcc<3.45V) ................................................................................................. 19
7.5 Digital Timing Characteristics .......................................................................................................................................... 20
transceiver for 10Base-T and 100Base-TX with
5-port 10/100M UTP or
4-port 10/100M UTP + 1-port MII/SNI
PHY mode MII/SNI interface for router application
MAC mode MII interface for HomeLAN/100Base-FX
application
1Mbit internal RAM for packet buffer
Internal 1K look-up table entries
25MHz crystal or OSC input
Supports broadcast storm filtering function
Support full duplex 802.3x flow control and half
duplex back-pressure flow control
LED indicators for link/activity, speed, full/half duplex
and collision
LEDs blinking upon reset for LED diagnostics
Unmanaged operation by strapping upon reset
Power saving with cable detection
Low power consumption at 3.3V operating voltage
128-pin PQFP package
Non-blocking wire-speed reception and transmission
Fully compliant with IEEE 802.3/802.3u
2. General Description
The RTL8305S is a highly integrated layer 2 single chip switch controller which incorporates 5 MACs (Media Access
Controller), 5 physical layer transceivers, 1-Mbit SRAM and 1K-entry look-up table into one single chip.
The RTL8305S contains 5 ports, and each one provides support for a 10Base-T (10Mbps) or 100Base-TX (100Mbps) network
connection. The fifth port (port 4) can be configured as a MII/SNI to work with a routing engine, HomePHY or a fiber
transceiver for a 100Base-FX application. And each operation mode can be easily set up by hardware strapping upon restart or
power-on.
The RTL8305S is designed for a stand-alone switch system through hardware strapping upon reset to achieve unmanaged
operation and can be easily integrated with xDSL/Cable modem router. With the least peripheral components and using a
25MHz crystal, the RTL8305S has the best system cost structure. The integrated RTL8305S chip benefits from low power
consumption and ease of use for SOHO 5-port switch or xDSL/Cable router applications.
ENBKPRS 78 I Enable Back Pressure: This pin has no effect on port4 if it is operated as
ENFCTRL 77 I Enable Flow Control: The RTL8305S will advertise its ability with flow
ENBRDCTRL 80 I Enable Broadcast Control: This is for the UTP and MII port.
LED_BLNK_TIME 89 I LED Blinking Time: This pin controls the blinking speed of the activity
DIS_RST_BLNK# 90 I Disable Reset Blinking: This pin controls the blinking of LEDs during
NWAYHALF# 76 I Nway Half Duplex: This pin advertises Nway ability to the link partner.
TEST# 121 O Te st : An internal test pin
11,12,15
16,27,28
31,32,127
128
3,4,7,8
19,20,23
24,35,36
AI
Differential Receive Data Input
AO
Differential Transmit Data Output
an MII port.
1: Enable (UTP ports only)
0: Disable
control during auto-negotiation. This pin has no effect on port4 if it is operated
as an MII port.
1: Enable Flow control (UTP ports only)
0: Disable
1: Enable
0: Disable
and collision LEDs.
1: 43ms
0: 120ms
reset and power up. Set to 0, the LEDs will not blink on reset or power up.
1: Enable
0: Disable
Setting this pin to 0 will advertise an Nway ability with 10/100 half duplex only.
1: Nway ability supports full duplex
0: Nway ability supports half duplex only
1
1
1
1
1
1
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5.3 Port4 Related Pins
Pin Name Pin No. Type Description Default
MRXD[3:0]
/MTXD[3:0]
MRXDV/MTXEN 60 I For MII MAC mode, this pin represents MRXDV, MII receive data valid.
MRXC/MTXC 59 I/O For MII MAC mode, it is receive clock, MRXC (acts as input).
MCOL 58 I/O For MII MAC mode, this pin represents collision (acts as input)
MTXD[3:0]
/MRXD[3:0]
MTXEN/MRXDV 52 O For MII MAC mode, this pin represents MTXEN, MII transmit enable.
MTXC/MRXC 51 I/O For MII MAC mode, this pin is a transmit clock, MTXC (acts as input).
P4MODE[1:0] 97,98 I Select Port 4 Operating Mode: 00: SNI PHY mode
P4LNKSTA# 49 I Port 4 Link Status: When P4MODE[1]=1 (UTP/MII MAC mode), this
P4DPXSTA# 48 I Active Low Duplex Status: 1: Half duplex
P4SPDSTA# 47 I Active Low Speed Status: 1: 10Mbps
P4FLCTRL# 46 I Active Low Flow Control Enable: When P4 is operated in UTP mode,
ENP4LED 91 I Enable Port 4 LED: In UTP applications, this pin should be floating to
SEL_MIIMAC# 68 O Select MII MAC: When P4MODE[1]=1, this pin indicates whether UTP
67,66,63
61
57,56,55
54
I For MII MAC mode, these pins are MRXD[3:0], MII receive data nibble.
For MII PHY mode, these pins are MTXD[3:0], MII transmit data nibble.
For SNI PHY mode, MTXD[0] is serial transmit data.
For MII PHY mode, this pin represents MTXEN, MII transmit enable.
For MII/SNI PHY mode, it is transmit clock, MTXC (acts as output).
For MII/SNI PHY mode, this pin represents collision (acts as output)
O For MII MAC mode, these pins are MTXD[3:0], MII transmit data nibble.
For MII PHY mode, these pins are MRXD[3:0], MII receive data nibble.
For SNI PHY mode, MRXD[0] is serial receive data.
For MII PHY mode, this pin represents MRXDV, MII receive data valid.
For MII/SNI PHY mode, this pin is a receive clock, MRXC (acts as output).
01: MII PHY mode
1x: UTP / MII MAC mode
pin decides the link status of the MII port. If both UTP and MII MAC are
linked OK, UTP has higher priority.
When P4MODE[1]=0 (PHY mode), this pin decides link status of Port4.
0: Full duplex
When P4 is operated in UTP mode, this pin has no effect.
0: 100Mbps
This pin must be kept floating for the three applications listed below.
This is because the speed is either determined by auto-negotiation or
fixed at 1M/10M Hz.
1. For UTP mode, speed is determined by the auto-negotiation procedure.
2. For HomePNA (MII MAC mode), speed is determined by RXC and
TXC from HomePHY running at 1Mbps.
3. For SNI PHY mode, speed is dedicated to 10MHz clock rate.
this pin has no effect.
1: Disable
0: Enable
drive the LEDs of port 4.
1: Drive LED pins of port4
0: Tri-state LED pins of port4
path or MII MAC path is selected.
1: UTP is selected
0: MII port is selected
While P4MODE[1]=1, the RTL8305S supports UTP/MII MAC auto-detect
function via the link status of P4 UTP and the status of P4LINKSTA# with
priority UTP over MII.
11
1
1
1
1
1
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5.4 LED Pins
Pin Name Pin No. Type Description Default
LED_ACT[4:0] 119,116
111,108
104
LED_DPX[4:0] 118,115
110,107
103
LED_SPD[4:0] 120,117
113,109
105
O Active low (Link + Activity) LED pins.
O Active low (Fullduplex + Collision) LED pins.
O Active low Speed100 LED pins.
1
1
1
5.5 Power Pins
Pin Name Pin No. Type Description Default
TVDD 5,6,21
22,37
RVDD 13,14,29
30,126
AVDD 125 P 3.3V Analog Power
MVDD 38 P 3.3V Internal RAM Power
VDD 43,53,62
70,87,100
106,114
RGND 1,10,17
26,33
TGND 2,9,18
25,34
AGND 123 P Analog GND
MGND 64 P Internal RAM GND
GND 39,50,65
79,94,102
112,122
P 3.3V Analog Transmit Power
P 3.3V Analog Receive Power
P 3.3V Digital Power
P Analog Ground
P Analog Ground
P Digital GND
5.6 Miscellaneous Pins
Pin Name Pin No. Type Description Default
X1 44 I 25MHz crystal or oscillator clock input
X2 45 O To crystal input. When using an oscillator this pin should be kept floating.
CK25MOUT 71 O 25MHz clock output
RESET# 40 I Active low reset signal. To complete the reset function, this pin must be
asserted for at least 10ms. After reset, about 30ms is needed for the
RTL8305S to complete the internal test function and initialization.
IBREF 124 A Control transmit output waveform Vpp. This pin should be grounded
through a 1.96KΩ resistor.
TESTCLK 41 I Test clock
TESTDATA 42 I/O Test data
5.7 Reserved Pins
Pin Name Pin No. Type Description Default
RESERVED 69 I This pin is reserved for internal use and should be left floating.
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RTL8305S
6. Functional Description
6.1 Introduction
Providing five 10/100 Mbps Ethernet channels and one MII port, the RTL8305S can be configured for either a five port 10/100
Ethernet application or a four 10/100 port Ethernet with an extra MII/SNI port. The MII/SNI port can be connected to an
external processor for routing purposes as public area network devices do, referred to as MII/SNI PHY mode, or connected to
a HomePNA physical chip or 100Base-FX PHYceiver, referred to as MII MAC mode.
In MII/SNI PHY mode, pins RXC, RXDV, and RXD correspond to TXC, TXEN, and TXD. In MII MAC mode, TXC, TXEN
and TXD correspond to RXC, RXDV and RXD.
The frame buffer is composed of 1M bits of built-in memory. The address look-up table for MAC addresses learning/searching
consists of 1K direct-mapping entries.
The RTL8305S uses Nway auto-negotiation to complete the UTP port connections of physical links which conform to IEEE
802.3u specifications. IEEE 802.3x full duplex flow control is supported. When operating in half duplex mode, a proprietary
back-pressure algorithm is implemented to prevent traditional hub devices from partitioning due to excessive collisions.
The RTL8305S supports non-blocking wire speed forwarding rates and special designs to resolve head-of-line blocking problems
and channel-capture problems. A broadcast storm filtering function is also provided for abnormal broadcast traffic issues.
6.2 Switch Core Functional Overview
6.2.1 Address Search, Learning and Aging
The RTL8305S contains a full 1K of look-up table entries and uses a direct-mapping scheme to achieve address search and
learning.
By extracting the least 10 bits of a destination MAC address to index the 1K-entry look-up table, the RTL8305S can decide
where the packet goes. If the searching result indexes to an empty entry, the packet is broadcast to all other ports. On the other
hand, the RTL8305S extracts the least 10 bits of a source MAC address to index the 1K-entry look-up table. If the result
indexes to an empty entry, it records the source MAC address and related switching information. If the result leads to an
occupied entry with different switching information, it updates the entry with the new information. This is referred to as
‘learning.’ The look-up engine will update time stamp information of an entry whenever the corresponding source MAC
address appears. If the time information is not updated for a period of time, the entry will be removed, referred to as the aging
process. The maximum aging time for the RTL8305S is approximately 300 seconds, and the minimum aging time is
approximately 200 seconds.
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6.2.2 Buffer Management
The 1M bit embedded memory buffer is divided into a packet buffer, which is used for data buffering, and a page pointer block
(PPB), which is used by the buffer manager. The Packet buffer is constructed of approximately 512 256-byte pages. Each page
includes 8-bytes of header information, which consists of next page pointer, packet byte count, and 248 bytes of data. The
linked pages construct a whole received packet which will be forwarded later according to its destination. The buffer manager
gets free page pointers from PPB and releases to each port to provide space for incoming packet buffering. When the buffer
manager can not support free page pointers any more, it indicates a buffer full condition and 802.3x flow control or back
pressure congestion control is implemented. If no flow control algorithms are activated, packets are dropped.
Buffer Manager
Free Page Pointers
Page177 PTR
Page180 PTR
Page193 PTR
Page189 PTR
Free Page Pointer FIFO
Page177
Page180
Page189
Page193
Frame Buffer
6.2.3 Data Reception
Each port contains a Receive FIFO for incoming packets, which are from physical medium, and a Free Page Pointer FIFO for
packet buffering indexes. Free Page Pointers are obtained from the Buffer Manager. Once a packet is received, it is segmented
into 248-byte pieces (as is fit into pages) and then moved into a packet buffer by the Receive DMA Engine with an 8-byte
header in every page.
6.2.4 Data Forwarding
Each port contains a Transmit FIFO, a Transmit Free Page Pointer FIFO and a Transmit Start Address Queue. The Transmit
Free Page Pointer FIFO stores Free Pages Pointers which have just been released from transmitted packets, and will return
these Free Pages to the Buffer Manager for buffering indexes of the next incoming packets. The Transmit Start Address Queue
keeps the first page pointer of every egress packet, which is from the transmit command issued by the reception port (source
port). The destination ports identify every transmit command on the global bus and receive it if they are the outlets. Finally, the
Transmit DMA engine of each port starts the DMA to move the pages (which construct a whole packet) to Transmit FIFO and
then to the physical medium. For broadcast packets, it’s the duty of the last port which finishes the transmission action last to
return the Transmit Free Page Pointers to the Buffer Manager.
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6.2.5 Flow Control
The RTL8305S supports IEEE 802.3x full duplex flow control and half duplex back-pressure congestion control. Once
the full duplex flow control ability is enabled via ENFCTRL, the Nway ability with full duplex flow control will be
negotiated during the auto-negotiation process. When operating in half duplex mode, a proprietary back-pressure
algorithm is enabled via the ENBKPRS pin, which can prevent traditional hub devices from partition due to excessive
collisions. For MII port applications, the same functions will be applied to port4 depending on the state of P4FLCTRL#
and P4DUPSTA#. If port4 is not configured to MII port application, it acts as a UTP port and behaves according to the
configuration of the ENFCTRL and ENBKPRS pins.
6.2.6 Back-off Algorithm
The RTL8305S implements the truncated exponential back-off algorithm compliant to the 802.3 standard. The collision
counter will be reset after 16 consecutive collisions, which leads to a smaller back-off time.
6.2.7 Inter-Frame Gap
The Inter-Frame Gap is 9.6us for 10Mbps Ethernet and 960ns for 100Mbps Fast Ethernet.
6.2.8 Illegal Frame
Illegal frames such as CRC error packets, runt packets ( packet length less than 64 bytes) and oversize packets (packet length
greater than 1536 bytes) will be discarded.
6.2.9 Broadcast Storm Control
The RTL8305S processes broadcast storm control via the latched value of the EnBrdCtrl pin upon reset. Once enabled, the
incoming consecutive broadcast packets will be discarded after consecutive 64 broadcast packets are received during an 800ms
time window. Any non-broadcast packets can reset the time window and broadcast counter such that the scheme restarts.
6.3 Physical Layer Functional Overview
6.3.1 Auto-negotiation
The RTL8305S obtains the states of duplex, speed and flow control ability through the auto-negotiation mechanism, defined in
IEEE802.3u specifications, for each UTP port. During auto-negotiation, each port advertises its ability to its link partner and
compares ability with those received from its link partner. By default, the RTL8305S advertises full capabilities (100Full,
100Half, 10Full, 10Half) together with flow control ability.
Asserting NWAYHALF# sets the Nway ability of the RTL8305S to half duplex only (100Half, 10Half). Deasserting
ENFCTRL sets the Nway ability without the flow control function. ENBKPRS is a pin to enable the half duplex flow control
scheme, which is defined in auto-negotiation. The MII port obtains its duplex, speed, flow control and link states from pins as
described in section 5.5.
6.3.2 10Base-T Transmit Function
The output 10Base-T waveform is Manchester-encoded and driven into the network medium. The internal filter shapes the
driven signals to reduce EMI emission, eliminating the need for an external filter.
6.3.3 10Base-T Receive Function
The Manchester decoder converts the incoming serial stream to NRZ data when the squelch circuit detects that the signal level
has exceeded the configured squelch level.
6.3.4 Link Monitor
The 10Base-T link pulse detection circuit always monitors the RXIP/RXIN pins for the presence of valid link pulses.
Auto-polarity is implemented to correct the detected reverse polarity of RXIP/RXIN signal pairs.
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RTL8305S
6.3.5 100Base-TX Transmit Function
The 100Base-TX transmit function performs parallel to serial conversion, 4B/5B coding, scrambling, NRZ/NRZI conversion,
and MLT3 encoding. After 4B/5B coding, the 5-bit serial data stream is scrambled as defined by the TP-PMD Stream Cipher
function to flatten the power spectrum energy such that EMI effects can be significantly reduced.
The scrambled seed is unique for each port, based on PHY addresses. After scrambling, the bit stream is driven into the
network medium in the form of MLT-3 signaling. Multi-level signaling technology moves the power spectrum energy from
high frequency to low frequency, which also benefits EMI emission issues.
6.3.6 100Base-TX Receive Function
The receive path includes a receiver composed of an adaptive equalizer and DC restoration circuits, to compensate for the
incoming distortion of the MLT-3 signal, MLT-3 to NRZI, NRZI to NRZ converter to convert analog signaling to a digital
bit-stream, and a PLL circuit to clock data bits precisely with minimum bit error rate. The de-scrambler, 5B/4B decoder and
serial-to-parallel conversion circuits follow. Finally, the converted parallel data is fed into the MAC.
6.3.7 Power Saving Mode
The RTL8305S implements power saving mode on per port basis. A port automatically enters power saving mode 10 seconds
after the cable is disconnected from it. Once a port enters power saving mode, it transmits normal link pulses only on its
TXOP/TXON pins and keeps monitoring RXIP/RXIN to try to detect any incoming signals, which might be a 100Base-TX
MLT-3 idle pattern, 10Base-T link pulses or Nway’s FLP (Fast Link Pulses). After it detects any incoming signals, it wakes up
from the power saving mode and operates in the normal mode according to the result of the connection.
6.4 LED
The RTL8305S supports three parallel LEDs for each port. LED_ACT indicates activity and link status, LED_DPX indicates
collision and duplex status, and LED_SPD indicates operating speed with state ‘0’ equal to 100Mbps. All LED pins are active
low, and blink when presenting activity and collision states. During power-on reset, the RTL8305S supports diagnostics of
chip reset and LED functions by blinking all parallel LEDs once. This function can be disabled by asserting
DIS_RST_BLINK# to 0. LED_BLINK_TIME determines LED blinking period for activity and collision, with 1 = 43ms and 0
= 120ms. LEDs corresponding to port 4 can be tri-stated (disable LED functions) for MII port applications by pulling
ENP4LED low.
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6.5 MII Port
6.5.1 General Description
RTL8305S
POW ER-ON
RESET
0
SNI PHY
10M bps
(10M H z)
P4M O D E[0]
PH Y modeM AC mode
P4M O D E[1]
MIISN I
1
P4SPDSTA #P4LNK STA#
MII PH Y
10M bps
(2. 5M H z)
0
MII PH Y
100M bps
(25M H z)
10
MII
NO1YES
UTP LINK ON?
1
HomeLAN/100FX
(1M/2.5M/25MHz)
SEL_MIIMAC#=0
0
MII M AC
UTP
UTP Port
10/100Base-T
SEL_MIIMAC#=1
The RTL8305S supports an extra MII interface for external devices. Two modes are implemented on the MII port, MII/SNI
PHY mode, and MII MAC mode. In MII/SNI PHY mode, a routing engine can connect ADSL or a cable modem to a LAN
through the MII port of the RTL8305S. In MII MAC mode, other types of LAN medium can be supported such as HomePNA
or 100Base-FX via the underlying physical devices through the MII port of the RTL8305S. The MII signals do not include
MTXER,MRXER and MCRS for RTL8305S. MDC/MDIO signals are also not supplied. Additional pins are used to complete
link, speed, duplex and flow-control settings described as follows.
When port4 is configured to something other than a UTP port, i.e. MII port is activated, four input pins, P4LNKSTSA#,
P4DPXSTA#, P4SPDSTA# and P4FLCTRL# are provided to determine link, duplex, and speed statuses as well as flow
control ability similar to force mode. These four pins are active low.
If P4LNKSTA#=0, the RTL8305S takes the MII port as link on, and will forward/receive packets to/from the MII port.
If P4DPXSTA#=0, the RTL8305S takes the MII port as full duplex, allowing simultaneous Tx/Rx.
If P4SPDSTA#=0, the RTL8305S takes the MII port as 100Base-TX, and outputs a 25MHz clock signal from the MTXC and
MRXC pins while in MII PHY mode. If P4SPDSTA#=1, it outputs a 2.5MHz clock signal instead. For SNI PHY mode
(P4MODE[1]=0, P4MODE[0]=0), both MTXC and MRXC are 10MHz clock output signals and P4SPDSTA# should be
floating. For MII MAC mode (P4MODE[1]=1), MTXC and MRXC are clock inputs from the underlying physical device.
It is suggested to keep P4SPDSTA# floating for SNI PHY mode and MII MAC mode for HomePNA applications, due to the
dedicated speed of these two applications.
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The other active-low input pin is P4FLCTRL#, which determines if flow control algorithm is enabled through the MII port.
(default P4FLCTRL#=1 )
If P4FLCTRL#=0 and P4DPXSTA#=0, 802.3x flow control packets will flow through the MII port.
If P4FLCTRL#=0 and P4DPXSTA#=1, a back-pressure algorithm will be implemented through the MII port.
If P4FLCTRL#=1, no flow control algorithm is performed on the MII port.
All three input pins, P4DPXSTA#, P4SPDSTA#, and P4FLCTRL#, have no effect when P4LNKSTA#=1.
It is important to note that the MRXD[3:0] pins in MII/SNI PHY mode are MTXD[3:0] for MII MAC mode, and vice versa.
Also the same for pin MRXDV vs. MTXEN, and pin MRXC vs. MTXC.
NOTE: There are no MRXER, MTXER, MCRS and SMI (MDC/MDIO) pins for MII signaling. Because of the absence of
MCRS, system designers can wire MRXDV directly to CRS and RXDV of the opposite chip.
R TL 8305S
x
x
x
x
x
x
x
x
Floating=High
Floating=High
Floating=High
Floating=High
Floating=High
Floating=High
Floating=High
Not Used
P4Mode[1]
P4Mode[0]
P4LnkSta#
P4SpdSta#
P4DupSta#
P4FlCtrl#
EnP4Led
SelMiiMac#
59 MRXC/MTXC
60 MRXDV/MTXEN
67~61 MRXD[3:0]
51 MTXC
52 MTXEN
57-54 MTXD[3:0]/MRXD[3:0]
58 COL
/MTXD[3:0]
/MRXC
/MRXDV
4
All should be floa ting
4
5 UTP Mode (Default five port switch application)
For general cases, most of the option pins should be floating (=High=Enable), except EnBrdCtrl. This means that EnBrdCtrl
should be pulled down (=Low=Disable) for normal applications.
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The illustrations below show a summary of MII/SNI application circuits for port4 of the RTL8305S.
Note that, as described above, the pins MRXC, MRXDV and MRXD in MII/SNI PHY mode are pins MTXC, MTXEN and
MTXD in MII MAC mode, and vice versa.
R TL8305S
Routing Engine
Routing Engine
Floating=High
x
Pull-down=Link On
Note1
Note1
Note1
Floating=High
x
x
Pull-down=Link On
Floating=10M
x
Note1
Note1
Floating=High
x
x
Not used
Not used
P4Mode[1]
P4Mode[0]
P4LnkSta#
P4SpdSta#
P4DupSta#
P4FlCtrl#
EnP4Led
SelMiiMac#
P4Mode[1]
P4Mode[0]
P4LnkSta#
P4SpdSta#
P4DupSta#
P4FlCtrl#
EnP4Led
SelMiiMac#
51 MTXC/MRXC
52 MTXEN/MRXDV
59 MRXC/MTXC
60 MRXDV/MTXEN
67~61
58 COL
R TL8305S
51 MTXC/MRXC
52 MTXEN/MRXDV
54
59 MRXC/MTXC
60 MRXDV/MTXEN
61
58 COL
/MRXD[3:0]
MTXD[3:0]57-54
MRXD[3:0]/MTXD[3:0]
MTXD[0] /MRXD[0]
MRXD[0]/MTXD[0 ]
25M/2.5MHz
4
4
MII PHY mode
10MHz
1
1
RXC
CRS
RXDV
RXD[3:0]
TXC
TXEN
TXD[3:0]
COL
RXC
CRS
RXDV
RXD
TXC
TXEN
TXD
COL
SNI PHY mode
R TL8305S
Floating=High
x
Floating=High
x
Pull-down=Link On
Floating=High
x
Floating=High
x
Floating=High
x
Floating=High
x
Used
P4Mode[1]
P4Mode[0]
P4LnkSta#
P4SpdSta#
P4DupSta#
P4FlCtrl#
EnP4Led
SelMiiMac#
59 MRXC/MTXC
60 MRXDV/MTXEN
67~61 MRXD[3:0]
51 MTXC
/MRXC
52 MTXEN
/MRXDV
57-54 MTXD[3:0]/
58 COL
MTXD[3:0]
/
MRXD[3:0]
1MHz
4
4
RXC
CRS
RXDV
RXD[3:0]
TXC
TXEN
TXD[3:0]
COL
HomePHY
A M 79C 901A
D P83851
MII MAC mode (HomePNA Application)
R TL8305S
Floating=High
x
Floating=High
x
Pull-down=Link On
Pull-down=100M
Note1
Note1
Floating=High
x
Used
P4Mode[1]
P4Mode[0]
P4LnkSta#
P4SpdSta#
P4DupSta#
P4FlCtrl#
EnP4Led
SelMiiMac#
59 MRXC/MTXC
60 MRXDV/MTXEN
67~61 MRXD[3:0]/
51 MTXC
/MRXC
52 MTXEN
/MRXDV
57-54 MTXD[3:0]/
58 COL
MTXD[3:0]
MRXD[3:0]
25MHz
4
4
Single PH Y
RXC
CRS
RXDV
RXD[3:0]
TXC
TXEN
TXD[3:0]
COL
MII MAC mode (100Base-FX Application)
Fiber
T rans ceiber
Note 1: Floating or Pull-down states depend on application.
Note 2: For general cases, most of the option pins should be floating (=High=Enable), except for EnBrdCtrl. This means that
EnBrdCtrl should be pulled down (=Low=Disable) for normal applications.
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RTL8305S
6.5.2 MII/SNI PHY Mode
In routing applications, the RTL8305S cooperates with a routing engine to communicate with a WAN (Wide Area Network)
through MII/SNI. In such applications, P4LNKSTA# =0 and P4MODE[1] are pulled low upon power-on reset. P4MODE[0]
determines whether MII or SNI mode is selected. In MII (nibble) mode (P4MODE[0]=1), P4SPDSTA# =0 results in MII
operating at 100Mbps with MTXC and MRXC running at 25MHz; however, P4SPDSTA#=1 leads to MII operating at 10Mbps
with MTXC and MRXC running at 2.5MHz. In SNI (serial) mode (P4MODE[0]=0), P4SPDSTA# has no effect and must be
floating. SNI mode operates at 10Mbps only, with MTXC and MRXC running at 10MHz. In SNI mode, RTL8305S does not
loopback RXDV signals as a response to TXEN and does not support heart-beat functions (asserting the COL signal for each
complete TXEN signal).
By pulling-up ENP4LED (internal default =1), the RTL8305S displays the MII/SNI status through LEDs of port 4, such as
activity/link, collision/duplex, and speed.
6.5.3 MII MAC Mode
In HomePNA/100Base-FX applications, the RTL8305S provides the MII interface to the underlying HomePNA or
100Base-FX related physical devices to communicate with other types of LAN medium. In such applications, P4MODE[1] is
pulled high upon power-on reset and the RTL8305S supports the UTP/MII auto-detection function. When both UTP and MII
are active (link on), the UTP port has a higher priority over the MII port. In HomePNA applications, P4SPDSTA# must be
floating and, since HomePNA is half-duplex only, P4DPXSTA# should be floating as well. It is recommend to pull
P4LNKSTA# low instead of being wired to the LINK LED pin of the HomePHY because of the unstable link state of the
HomePHY configuration, which is a characteristic based on the HomePNA 1.0 standard. For 100Base-FX applications,
P4LNKSTA# =0, P4SPDSTA# =0 and P4DPXSTA# depends on the application.
By pulling-up ENP4LED (internal default =1), the RTL8305S displays the MII status through the LEDs of port 4, such as
activity/link, collision/duplex, and speed. Pin SEL_MIIMAC# can be used to indicate that the MII MAC port is active by a
LED for the sake of UTP/MII auto-detection. Finally, a 25MHz clock output (CK25MOUT) can be used as a clock source for
the underlying HomePHY/100Base-FX physical devices.
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A brief application for HomePNA and 100Base-FX is depicted below.
3.3V
RTL8305S
3.3V3.3V
P4MODE[1]
P4MODE[0]
LEDACT[4]
LEDDPX[4]
LEDSPD[4]
3.3V
RTL8305S
P4LNKSTA#
P4SPDSTA#
P4DPXSTA#
P4FLCTRA#
CK25MOUT
SEL_MIIMAC#
ENP4LED
MII
HomePHY
LED_LINK#
LED_ACT#
LED_COL#
LED_SPD#
Common LEDs (RTL8305S driving)
MII MAC mode (UTP / HomeLAN auto-detect)
3.3V3.3V
P4MODE[1]
P4MODE[0]
CK25MOUT
RTL8305S
LEDACT[4]
LEDDPX[4]
LEDSPD[4]
P4LNKSTA#
P4SPDSTA#
P4DPXSTA#
P4FLCT RA#
SEL_MIIMAC#
ENP4LED
MII
3.3V
3.3V
Single
PHY
RD+/-TD+/-SD+/-
LED_LINK#
LED_ACT#
LED_COL#
LED_SPD#
Fiber Transceiver
Common LEDs (RTL8305S driving)
MII MAC mode (UTP / 100Base-FX auto-detect)
As illustrated above, P4LNKSTA# needs to be pulled low to enable the MII MAC port, accompanied with P4MODE[1] pulled
high. An LED connected to SEL_MIIMAC# pin can indicate whether the UTP or MII port is selected.
For 100Base-FX applications, the Link LED status pin can even be wired to P4LNKSTA# to implement the UTP/MII
auto-detection feature with no need to permanently disable port4 UTP capabilities. For the RTL8305S, UTP priority takes over
the MII port if both are link on.
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RTL8305S
7. Electrical Characteristics
7.1 Absolute Maximum Ratings
WA R N IN G : Absolute maximum ratings are limits beyond which may cause permanent damage to the device or affect device
reliability. All voltages are specified reference to GND unless otherwise specified.
Parameter Min Max Units
Storage Temperature -45 +125
Vcc Supply Referenced to GND -0.5 +4.0 V
Digital Input Voltage -0.5 Vcc V
DC Output Voltage -0.5 Vcc V
7.2 Operating Range
Parameter Min Max Units
Ambient Operating Temperature(Ta) 0 +60
Vcc Supply Voltage Range(Vcc) 3.15 3.45 V
7.3 DC Characteristics (0°C<Ta<60°C, 3.15V<Vcc<3.45V)