KS8721B/BT
Micrel
KS8721B/BT
2.5V 10/100BasTX/FX MII Physical Layer Transceiver
Rev. 2.2
General Description
Operating at 2.5 volts to meet low voltage and low power
requirements, the KS8721B/BT is a 10BaseT/100BaseTX/
FX Physical Layer Transceiver, which provides an MII to
transmit and receive data. It contains the 10BaseT Physical
Medium Attachment (PMA), Physical Medium Dependent
(PMD), and Physical Coding Sub-layer (PCS) functions.
Moreover, the KS8721B/BT has on-chip 10BaseT output
filtering, which eliminates the need for external filters and
allows a single set of line magnetics to be used to meet
requirements for both 100BaseTX and 10BaseT.
The KS8721B/BT can automatically configure itself for 100 or
10 Mbps and full or half duplex operation, using on-chip Auto-
Negotiation algorithm. It is an ideal choice of physical layer
transceiver for 100BaseTX/10BaseT applications.
Data sheets and support documentation can be found on
Micrel’s web site at www.micrel.com.
Features
• Single chip 100BaseTX/100BaseFX/10BaseT physical
layer solution
• 2.5V CMOS design, power consumption <200mW
(excluding output driver current )
• Fully compliant to IEEE 802.3u standard
• Supports Media Independent Interface (MII) and
Reduced MII (RMII)
• Supports 10BaseT, 100BaseTX and 100BaseFX with
Far_End_Fault Detection
• Supports power down mode and power saving mode
• 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 mode
• On-chip built-in analog front end filtering for both
100BaseTX and 10BaseT
Functional Diagram
TX+
TX-
Transmitter
10/100
Pulse
Shaper
NRZ/NRZI
MLT3 Encoder
4B/5B Encoder
Scrambler
Parallel/Serial
Parallel/Serial
Manchester Encoder
RX+
RX-
Adaptive EQ
Base Line
Wander Correction
MLT3 Decoder
NRZI/NRZ
Clock
Recovery
4B/5B Decoder
Descrambler
Serial/Parallel
MII/RMII
Registers
and
Controller
Interface
Auto
Negotiation
10BaseT
Receiver
Power
Down or
Saving
XI
XO
PLL
PWRDWN
Manchester Decoder
Serial/Parallel
TXD3
TXD2
TXD1
TXD0
TXER
TXC
TXEN
CRS
COL
MDIO
MDC
RXD3
RXD2
RXD1
RXD0
RXER
RXDV
RXC
LINK
LED
Driver
COL
FDX
SPD
Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com
August 2003
1
KS8721B/BT
MICREL [ MICREL SEMICONDUCTOR ]
