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April 2005 1 M9999-041405
KS8721CL Micrel, Inc.
KS8721CL
3.3V Single Power Supply 10/100BASE-TX/FX MII Physical Layer Transceiver
Rev. 1.2
General Description
The KS8721CL is a 10BASE-T, 100BASE-TX, and 100BASE-
FX physical layer transceiver providing MII/RMII interfaces to
MACs and switches. Using a unique mixed-signal design that
extends signaling distance while reducing power consump-
tion, the KS8721CL represents Micrel’s fourth generation
single-port Fast Ethernet PHY.
The KS8721CL contains 10BASE-T physical medium attach-
ment (PMA), physical medium dependent (PMD), and physi-
cal coding sub-layer (PCS) functions. It also has on-chip
10BASE-T output filtering. This eliminates the need for
external filters and allows a single set of line magnetics to be
used to meet requirements for both 100BASE-TX and
10BASE-T.
The KS8721CL automatically configures itself for 100Mbps
or 10Mbps and full- or half-duplex operation, using an on-chip
auto-negotiation algorithm. It is the ideal physical layer
transceiver for 100BASE-TX/10BASE-T applications.
Features
•Single chip 100BASE-TX/100BASE-FX/10BASE-T
physical layer solution
•2.5V CMOS design; 2.5/3.3V tolerance on I/O
•3.3V single power supply with built-in voltage regulator;
Power consumption <340mW (including output driver
current)
• Fully compliant to IEEE 802.3u standard
• Supports MII and Reduced MII (RMII)
• Supports 10BASE-T, 100BASE-TX, and 100BASE-FX
with far-end-fault (FEF) detection
• Supports power-down and power-saving modes
• Configurable through MII serial management ports or via
external control pins
• Supports auto-negotiation and manual selection for
10/100Mbps speed and full-/half-duplex modes
• On-chip, built-in, analog front-end filtering for both
100BASE-TX and 10BASE-T
• Available in Lead-free and Industrial Temperature
packages.
Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
Functional Diagram
10/100
Pulse
Shaper
NRZ/NRZI
MLT3 Encoder
Parallel/Serial
Manchester Encoder
4B/5B Encoder
Scrambler
Parallel/Serial
Transmitter
TX+
TX-
Adaptive EQ
Base Line
Wander Correction
MLT3 Decoder
NRZI/NRZ
Clock
Recovery
4B/5B Decoder
Descrambler
Serial/Parallel
Auto
Negotiation
10BaseT
Receiver
Manchester Decoder
Serial/Parallel
PLL
LED
Driver
MII/RMII
Registers
and
Controller
Interface
RX-
RX+
XI
XO
SPD
FDX
ACTIVITY
LINK
Power
Down or
Saving
PWRDWN
RXC
TXD3
TXD0
TXD1
TXD2
RXD3
TXEN
TXC
TXER
MDC
MDIO
COL
CRS
RXER
RXD0
RXD1
RXD2
RXDV
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