LAN8720AI-CP-TR Standard Microsystems (SMSC), LAN8720AI-CP-TR Datasheet - Page 25
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LAN8720AI-CP-TR
Manufacturer Part Number
LAN8720AI-CP-TR
Description
Manufacturer
Standard Microsystems (SMSC)
Datasheet
1.LAN8720AI-CP-TR.pdf
(78 pages)
Specifications of LAN8720AI-CP-TR
Number Of Receivers
1
Protocols Supported
IEEE 802.3
Operating Supply Voltage (typ)
1.8/2.5/3.3V
Package Type
QFN
Operating Temperature Classification
Industrial
Mounting
Surface Mount
Operating Temperature (max)
85C
Operating Temperature (min)
-40C
Lead Free Status / Rohs Status
Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Company:
Part Number:
LAN8720AI-CP-TR
Manufacturer:
CHIPLUS
Quantity:
3 100
Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support
Datasheet
SMSC LAN8720/LAN8720i
3.2.1
3.2.2
3.2.3
the link partner is capable of half and full duplex modes, then auto-negotiation selects full duplex as
the highest performance operation.
Once a capability match has been determined, the link code words are repeated with the acknowledge
bit set. Any difference in the main content of the link code words at this time will cause auto-negotiation
to re-start. Auto-negotiation will also re-start if not all of the required FLP bursts are received.
The capabilities advertised during auto-negotiation by the transceiver are initially determined by the
logic levels latched on the MODE[2:0] configuration straps after reset completes. These configuration
straps can also be used to disable auto-negotiation on power-up. Refer to
Mode Configuration," on page 31
Writing the bits 8 through 5 of the
the capabilities advertised by the transceiver. Writing the
does not automatically re-start auto-negotiation. The
Register
via software by clearing the
Note: The device does not support “Next Page” capability.
Parallel Detection
If the LAN8720/LAN8720i is connected to a device lacking the ability to auto-negotiate (i.e. no FLPs
are detected), it is able to determine the speed of the link based on either 100M MLT-3 symbols or
10M Normal Link Pulses. In this case the link is presumed to be half duplex per the IEEE standard.
This ability is known as “Parallel Detection.” This feature ensures interoperability with legacy link
partners. If a link is formed via parallel detection, then the
Auto Negotiation Expansion Register
negotiation. The controller has access to this information via the management interface. If a fault
occurs during parallel detection, the
is set.
Auto Negotiation Link Partner Ability Register
is coded in the received FLPs. If the link partner is not auto-negotiation capable, then the
Negotiation Link Partner Ability Register
speed capability of the link partner.
Restarting Auto-negotiation
Auto-negotiation can be restarted at any time by setting the
Control
caused by signal loss. This may occur because of a cable break, or because of an interruption in the
signal transmitted by the link partner. Auto-negotiation resumes in an attempt to determine the new
link configuration.
If the management entity re-starts auto-negotiation by setting the
Basic Control
operations. Once the break_link_timer is completed in the Auto-negotiation state-machine
(approximately 1200ms), auto-negotiation will re-start. In this case, the link partner will have also
dropped the link due to lack of a received signal, so it too will resume auto-negotiation.
Disabling Auto-negotiation
Auto-negotiation can be disabled by setting the
Register
Control Register (Speed Select
negotiation is enabled.
Register. Auto-negotiation will also restart if the link is broken at any time. A broken link is
to zero. The device will then force its speed of operation to reflect the information in the
must be set before the new abilities will be advertised. Auto-negotiation can also be disabled
Register, the LAN8720/LAN8720i will respond by stopping all transmission/receiving
Auto-Negotiation Enable
bit and
for additional information.
Auto Negotiation Advertisement Register
DATASHEET
Parallel Detection Fault
is cleared to indicate that the Link Partner is not capable of auto-
Duplex Mode
is updated after completion of parallel detection to reflect the
25
is used to store the link partner ability information, which
Auto-Negotiation Enable
bit of the
Restart Auto-Negotiate
bit). These bits should be ignored when auto-
Link Partner Auto-Negotiation Able
Auto Negotiation Advertisement Register
bit of
Restart Auto-Negotiate
Basic Control
Link Partner Auto-Negotiation Able
Restart Auto-Negotiate
Section 3.7.2, "MODE[2:0]:
allows software control of
bit of the
Register.
bit of the
Revision 1.0 (12-09-09)
bit of the
Basic Control
Basic Control
bit of the
bit of the
Basic
Basic
Auto