KS8993
Micrel
KS8993
3-Port 10/100 Integrated Switch with PHY and Frame Buffer
Rev. 2.05
General Description
The KS8993 contains three 10/100 physical layer transceiv-
ers, three MAC (Media Access Control) units with an inte-
grated layer 2 switch. The device runs in two modes. The first
mode is a three port integrated switch and the second is as
a three port switch with the third port decoupled from the
physical port. In this mode access to the third MAC is provided
using a reverse or forward MII (Media Independent Interface)
such that an external MAC can be directly connected to the
KS8993. This interface also supports the 7-wire (serial net-
work interface) as used by some routing devices.
Useful configurations include a stand alone three port switch
as well as a two port switch with a routing element connected
to the extra MII port. The additional port is also useful for
public network interfacing.
The KS8993 has rich features such as VLAN and priority
queuing and is designed to reside in an unmanaged design
not requiring processor intervention. This is achieved through
I/O strapping at system reset time.
On the media side, the KS8993 supports 10BaseT,
100BaseTX and 100BaseFX as specified by the IEEE 802.3
committee.
Physical signal transmission and reception are enhanced
through use of analog circuitry that makes the design more
efficient and allows for lower power consumption and smaller
chip die size.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Functional Diagram
Look-Up
Engine
(1K Entries)
SRAM
Buffers
(16Kx32)
Queue
Management
Buffer
Management
FIFO and Flow Control
MAC
1
MAC
2
MAC
3
M
I
I
MII / SNI
(exclusive)
External
Interface
MRXD[3:0]
MRXDV
MCOL
MCRS
MRXCLK
MTXD[3:0]
MTXEN
MTXER
MTXCLK
MCOLIN
MRXD[0]
MRXDV
MCOL
MRXCLK
MTXD[0]
MTXEN
MTXCLK
Physical
Transceiver
1
RXP[1], RXM[1]
Physical
Transceiver
2
RXP[2], RXM[2]
Physical
Transceiver
3
RXP[3], RXM[3]
S
N
I
TXP[1], TXM[1]
TXP[2], TXM[2]
TXP[3], TXM[3]
LED
and
Programming
Interface
LED[1][3:0]
LED[2][3:0]
LED[3][3:0]
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
May 2005
1
KS8993
MICREL [ MICREL SEMICONDUCTOR ]
