KS8721BL/SL
3.3V Single Power Supply 10/100BASE-TX/FX
MII Physical Layer Transceiver
Rev. 1.3
Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com
June 2009
M9999-062509-1.3
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 configure themselves
for 100 or 10Mbps and full- or half-duplex operation,
using an on-chip auto-negotiation algorithm. They are 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
Functional Diagram
