Microchip Technology EVB8740, EVB8741 User Manual

EVB8740/EVB8741 Evaluation Board User Manual

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SMSC EVB8740/EVB8741 Revision 1.0 (04-29-13)

USER MANUAL

EVB8740/EVB8741 Evaluation Board User Manual

SMSC

LAN8740A/

LAN8741A

10/100

Ethernet

Magnetics

& RJ45

EVB8740/EVB8741

MII Ethernet

40-pin

Connector

1 Introduction

The LAN8740A/LAN8741A is a low-power, 10BASE-T/100BASE-TX physical layer (PHY) transceiver
with variable I/O voltage that is compliant with the IEEE 802.3, 802.3u, and 802.3az (Energy Efficient
Ethernet) standards. Energy Efficient Ethernet (EEE) support results in significant power savings during
low link utilizations.

The EVB8740/EVB8741 is a PHY Evaluation Board (EVB) that interfaces a Media Independent
Interface (MII) MAC controller to the LAN8740A/LAN8741A Ethernet MII PHY via a standard 40-pin
MII connector. The LAN8740A/LAN8741A is connected to an RJ45 Ethernet jack with integrated
magnetics for 10/100 connectivity. A simplified block diagram of the EVB8740/EVB8741 can be seen
in Figure 1.1.

Figure 1.1 EVB8740/EVB8741 Block Diagram

Note: Though the LAN8740A/LAN8741A supports an RMII mode of operation, the

EVB8740/EVB8741 evaluation board does not support this mode.

1.1 References

Concepts and material available in the following documents may be helpful when reading this
document. Visit www.smsc.com for the latest documentation.

 SMSC LAN8740A/LAN8741A Datasheets

 AN 25.3 Migrating from the LAN8710A/LAN8720A to the LAN8740/LAN8741/LAN8742

 AN 8.13 Suggested Magnetics

 SMSC LAN8740A/LAN8741A Evaluation Board Schematics

Revision 1.0 (04-29-13) 2 SMSC EVB8740/EVB8741

USER MANUAL

2 Board Details

This section includes the following EVB8740/EVB8741 board details:

 Power

 Configuration

 Mechanicals

2.1 Power

2.1.1 +5V Power

Power is normally supplied to the EVB8740/EVB8741’s +3.3V regulator externally via the +5V power
pins of the MII connector. If desired, the EVB8740/EVB8741 can be powered without +5V present on
the MII connector by supplying +5V to the TP2 (red) test point with ground connected to the TP4
(black) test point.

Note: Before connecting an external power supply to TP2, ensure power is not present on the MII

connector’s +5V pins. Connecting +5V simultaneously via the MII connector and TP2 may
result in permanent damage to the board.

EVB8740/EVB8741 Evaluation Board User Manual

2.1.2 VDDIO Power

The LAN8740A/LAN8741A’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 the TP4 (black) test point.

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 LAN8740A/LAN8741A’s internal +1.2V regulator can be optionally disabled. Refer to Section 2.2.4,

"Internal +1.2V Regulator Configuration (REGOFF)," on page 6 for additional information.

SMSC EVB8740/EVB8741 3 Revision 1.0 (04-29-13)

USER MANUAL

EVB8740/EVB8741 Evaluation Board User Manual

MII

Testpoints

VDDCR

Testpoint

Reset

Button

Integrated

RJ45 +

Magnetics

SPEED &

LINK/ACT

LEDs

(integrated in

magjack)

40-pin MII

connector

(P1)

VDDIO

Testpoint

+5V

Testpoint

+3.3V

Testpoint

SMSC

LAN8740A/

LAN8741A

GND

Testpoint

JP1 – JP4

AVDD_ETH

Testpoint

2.2 Configuration

The following sub-sections describe the various board features and configuration settings. A top view
of the EVB8740/EVB8741 is shown in Figure 2.1.

Figure 2.1 Top View of the EVB8740/EVB8741

2.2.1 PHY Address Configuration

The EVB8740/EVB8741 allows the user to configure the default PHY address at power-up via the
PHYAD[2:0] configuration straps. Tab l e 2 .1 details the proper configuration required for each PHY
address value. By default, all EVB8740/EVB8741 PHY address straps are configured to a value of “0”.

Table 2.1 PHYAD[2:0] Resistor Configuration

PHYAD[2:0] PULL-UP/DOWN RESISTORS

PHYAD[2:0]

000 (Default)

001

010

011

100

101

Depopulate Populate Depopulate Populate Depopulate Populate

Depopulate Populate Depopulate Populate Populate Depopulate

Depopulate Populate Populate Depopulate Depopulate Populate

Depopulate Populate Populate Depopulate Populate Depopulate

Populate Depopulate Depopulate Populate Depopulate Populate

Populate Depopulate Depopulate Populate Populate Depopulate

PHYAD2 PHYAD1 PHYAD0

R26R35R25R36R24R37

Revision 1.0 (04-29-13) 4 SMSC EVB8740/EVB8741

USER MANUAL