KS8721B/BT
Micrel
KS8721B/BT
2.5V 10/100BasTX/FX MII Physical Layer Transceiver
Rev. 2.2
General Description
Features
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.
• 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
TheKS8721B/BTcanautomaticallyconfigureitselffor100or
10Mbpsandfullorhalfduplexoperation, usingon-chipAuto-
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.
Functional Diagram
4B/5B Encoder
NRZ/NRZI
MLT3 Encoder
TXD3
TXD2
TXD1
TXD0
TXER
TXC
Scrambler
10/100
Pulse
Shaper
TX+
TX-
Parallel/Serial
Transmitter
Parallel/Serial
Manchester Encoder
TXEN
CRS
COL
MII/RMII
Registers
and
Controller
Interface
Adaptive EQ
RX+
RX-
Base Line
Wander Correction
MLT3 Decoder
NRZI/NRZ
4B/5B Decoder
Descrambler
Clock
Recovery
MDIO
MDC
RXD3
RXD2
RXD1
RXD0
RXER
RXDV
RXC
Serial/Parallel
Auto
Negotiation
10BaseT
Receiver
Manchester Decoder
Serial/Parallel
Power
Down or
Saving
LINK
COL
FDX
SPD
LED
Driver
XI
PLL
XO
PWRDWN
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