
May 2004
1
M9999-051704
KS8721BL/SL
Micrel
KS8721BL/SL
3.3V Single Power Supply 10/100BASE-TX/FX MII Physical Layer Transceiver
Rev. 1.1
General Description
Operating with a 2.5V core to meet low-voltage and low-
power requirements, the KS8721BL and KS8721SL are
10BASE-T/100BASE-TX/FX Physical Layer Transceivers
that use MII and RMII interfaces to transmit and receive data.
They contain 10BASE-T Physical Medium Attachment (PMA),
Physical Medium Dependent (PMD), and Physical Coding
Sub-layer (PCS) functions. The KS8721BL/SL also have 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 KS8721BL/SL automatically configures itself for 100 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 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
Micrel, Inc. 1849 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
10BASE-T
Receiver
Manchester Decoder
Serial/Parallel
PLL
LED
Driver
MII/RMII
Registers
and
Controller
Interface
RX-
RX+
XI
XO
SPD
FDX
COL
LINK
Power
Down or
Saving
PWRDWN
RXC
TXD3
TXD0
TXD1
TXD2
RXD3
TXEN
TXC
TXER
MDC
MDIO
COL
CRS
RXER
RXD0
RXD1
RXD2
RXDV