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SMSC EVB8720
USER MANUAL
Revision 1.1 (05-24-10)
EVB8720 Evaluation Board User Manual
1 Introduction
The LAN8720A is a low-power, small form factor, highly integrated analog interface IC for high-
performance embedded Ethernet applications. The LAN8720A requires only a single +3.3V supply and
provides an integrated +1.2V supply to run the core digital logic.
The EVB8720 is a PHY Evaluation Board (EVB) that interfaces a Reduced Media Independent
Interface (RMII) MAC controller to the LAN8720A Ethernet RMII PHY via a 40-pin connector. The
LAN8720A is connected to an RJ45 Ethernet jack with integrated magnetics for 10/100 connectivity. A
simplified block diagram of the EVB8720 can be seen in
Figure 1.1.
Note:
Revisions 1.1 and later of the EVB8720 Evaluation Board User Manual pertain to EVB8720
assembly number 6584. For information on the older, discontinued EVB8720 assembly number
7170AZ, refer to revision 1.0 of the EVB8720 Evaluation Board User Manual. For identification
purposes, the EVB8720 assembly number is silkscreened onto the front of the evaluation
board.
RMII
40-pin
Connector
SMSC
LAN8720A
10/100
Ethernet
Magnetics
& RJ45
Ethernet
EVB8720
Figure 1.1 EVB8720 Block Diagram
1.1
References
Concepts and material available in the following documents may be helpful when reading this
document.
Table 1.1 References
DOCUMENT
LOCATION
http://www.smsc.com/lan8720a
http://www.smsc.com/lan8720a
http://www.smsc.com/lan8720a
SMSC LAN8720A Datasheet
AN18-20 Migrating from the LAN8700 to the LAN8710A/LAN8720A
AN8-13 Suggested Magnetics
SMSC LAN8720A Evaluation Board Schematic
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USER MANUAL
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SMSC EVB8720
EVB8720 Evaluation Board User Manual
2 Board Details
This section includes the following EVB8720 board details:
Power
Configuration
Mechanicals
2.1
2.1.1
Power
+5V Power
Power is normally supplied to the EVB8720’s +3.3V regulator externally via the +5V power pins of the
40-pin connector. If desired, the EVB8720 can be powered without +5V present on the 40-pin
connector (P1) by supplying +5V to the TP2 (red) test point with ground connected to pin 20 of the J1
header.
Note:
Before connecting an external power supply to TP2, ensure power is not present on the 40-
pin connector’s +5V pins. Connecting +5V simultaneously via the 40-pin connector and TP2
may result in permanent damage to the board.
2.1.2
VDDIO Power
The LAN8720A’s VDDIO power may be supplied at a voltage other than +3.3V by depopulating resistor
R12 and supplying +1.6V to +3.6V externally via test point TP5 (purple), with ground connected to pin
20 of the J1 header.
Note:
Before connecting an external power supply to TP5, ensure that resistor R12 has been
removed. Connecting an external power supply to TP5 while resistor R12 is populated may
result in permanent damage to the board.
2.1.3
+1.2V Power
The LAN8720A’s internal +1.2V regulator can be optionally disabled. Refer to
Section 2.2.4, "Internal
+1.2V Regulator Configuration (REGOFF)," on page 7
for additional information.
SMSC EVB8720
USER MANUAL
3
Revision 1.1 (05-24-10)
EVB8720 Evaluation Board User Manual
2.2
Configuration
The following sub-sections describe the various board features and configuration settings. A top view
of the EVB8720 is shown in
Figure 2.1.
40-pin
Connector
(P1)
RMII
Testpoints
Reset
Button
VDDCR
Testpoint
Integrated
RJ45 +
Magnetics
SPEED &
LINK/ACT
LEDs
(integrated in
magjack)
+3.3V
Testpoint
VDDIO
Testpoint
+5V
Testpoint
SMSC
LAN8720A
Figure 2.1 Top View of the EVB8720
2.2.1
PHY Address Configuration
The EVB8720 allows the user to configure the default PHY address at power-up via the PHYAD[0]
configuration strap.
Table 2.1
details the proper configuration required for each PHY address value. By
default, PHYAD[0] is configured to a value of “0”.
Table 2.1 PHYAD[0] Resistor Configuration
PHYAD[0]
0 (Default)
1
PHYAD[0] PULL-UP/DOWN RESISTORS
R24
Depopulate
Populate
R37
Populate
Depopulate
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USER MANUAL
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SMSC EVB8720
EVB8720 Evaluation Board User Manual
2.2.2
Boot Mode Configuration
The EVB8720 can be configured to boot into a specific mode of operation at power-up via the
MODE[2:0] configuration straps.
Table 2.2
details the proper configuration required for each mode. By
default, all EVB8720 MODE[2:0] straps are configured to a value of “1”.
Note:
For additional details on each mode of operation, refer to the LAN8720A datasheet.
