Microchip Technology EVB8740 User manual

SMSC EVB8740/EVB8741 Revision 1.0 (04-29-13)
USER MANUAL
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EVB8740/EVB8741 Evaluation Board User Manual

EVB8740/EVB8741 Evaluation Board User Manual
Revision 1.0 (04-29-13) 2 SMSC EVB8740/EVB8741
USER MANUAL
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.
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
Figure 1.1 EVB8740/EVB8741 Block Diagram
SMSC
LAN8740A/
LAN8741A
10/100
Ethernet
Magnetics
& RJ45
EVB8740/EVB8741
MII Ethernet
40-pin
Connector

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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.
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.

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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.
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. Ta ble 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”.
Figure 2.1 Top View of the EVB8740/EVB8741
Table 2.1 PHYAD[2:0] Resistor Configuration
PHYAD[2:0]
PHYAD[2:0] PULL-UP/DOWN RESISTORS
PHYAD2 PHYAD1 PHYAD0
R26R35R25R36R24R37
000 (Default) Depopulate Populate Depopulate Populate Depopulate Populate
001 Depopulate Populate Depopulate Populate Populate Depopulate
010 Depopulate Populate Populate Depopulate Depopulate Populate
011 Depopulate Populate Populate Depopulate Populate Depopulate
100 Populate Depopulate Depopulate Populate Depopulate Populate
101 Populate Depopulate Depopulate Populate Populate Depopulate
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

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2.2.2 Reset Mode Configuration
The EVB8740/EVB8741 can be configured to reset into a specific mode of operation at power-up via
the MODE[2:0] configuration straps. Ta bl e 2. 2 details the proper configuration required for each mode.
By default, all EVB8740/EVB8741 MODE[2:0] straps are configured to a value of “1”.
Note: For additional details on each mode of operation, refer to the LAN8740A/LAN8741A datasheet.
110 Populate Depopulate Populate Depopulate Depopulate Populate
111 Populate Depopulate Populate Depopulate Populate Depopulate
Table 2.2 MODE[2:0] Resistor Configuration
MODE[2:0]
MODE[2:0] PULL-UP/DOWN RESISTORS
MODE2 MODE1 MODE0
R28R33R29R32R30R31
000
10BASE-T
Half Duplex
Auto-neg disabled
Depopulate Populate Depopulate Populate Depopulate Populate
001
10BASE-T
Full Duplex
Auto-neg disabled
Depopulate Populate Depopulate Populate Populate Depopulate
010
100BASE-TX
Half Duplex
Auto-neg disabled
Depopulate Populate Populate Depopulate Depopulate Populate
011
100BASE-TX
Full Duplex
Auto-neg disabled
Depopulate Populate Populate Depopulate Populate Depopulate
100
100BASE-TX
Half Duplex
Auto-neg enabled
Populate Depopulate Depopulate Populate Depopulate Populate
101
Repeater mode
Populate Depopulate Depopulate Populate Populate Depopulate
110
Power Down mode
Populate Depopulate Populate Depopulate Depopulate Populate
111 (Default)
All capable.
Auto-neg enabled
Populate Depopulate Populate Depopulate Populate Depopulate
Table 2.1 PHYAD[2:0] Resistor Configuration (continued)
PHYAD[2:0]
PHYAD[2:0] PULL-UP/DOWN RESISTORS
PHYAD2 PHYAD1 PHYAD0
R26R35R25R36R24R37

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2.2.3 nINT/TXER/TXD4 Pin Configuration (nINTSEL)
The nINT, TXER, and TXD4 functions share a common LAN8740A/LAN8741A pin. This pin can
operate in two functional modes: nINT (Interrupt) Mode and TXER/TXD4 Mode. TXER is also used in
EEE mode as TXER when TXEN = 1, and LPI when TXEN = 0. The nINTSEL configuration strap is
used to select one of these two modes. The EVB8740/EVB8741 must be properly configured for each
mode as follows:
nINT Mode
Depopulate R46.
Depopulate the 2-3 positions of JP3 and JP4.
Populate the 1-2 positions of JP3 and JP4 to pull-up the nINTSEL strap (nINT mode).
TXER/TXD4 Mode (Default EVB8740/EVB8741 Mode)
Depopulate the 1-2 positions of JP3 and JP4.
Populate the 2-3 positions of JP3 and JP4 to pull-down the nINTSEL strap (TXER/TXD4 mode).
Populate R46.
Note: The nINTSEL configuration strap shares functionality with LED2. Therefore, LED2 may function
active-high or active-low depending on the nINTSEL configuration. For additional information
on the functionality of the nINT/TXER/TXD4 and LED2/nINTSEL pins, refer to the
LAN8740A/LAN8741A Datasheet and LAN8740A/LAN8741A schematics.
2.2.4 Internal +1.2V Regulator Configuration (REGOFF)
The LAN8740A/LAN8741A provides the ability to disable the internal +1.2V regulator. When the
regulator is disabled, an external +1.2V must be supplied to the VDDCR pin (via TP3). Configuration
of the internal regulator is controlled by the REGOFF configuration strap. The EVB8740/EVB8741 must
be properly configured for each mode as follows:
Internal +1.2V Regulator Enabled (Default EVB8740/EVB8741 Mode)
Depopulate the 2-3 positions of JP1 and JP2.
Populate the 1-2 positions of JP1 and JP2 to pull-down the REGOFF strap (enable regulator).
Internal +1.2V Regulator Disabled
Depopulate the 1-2 positions of JP1 and JP2.
Populate the 2-3 positions of JP1 and JP2 to pull-up the REGOFF strap (disable regulator).
Note: The REGOFF configuration strap shares functionality with LED1. Therefore, LED1 may
function active-high or active-low depending on the REGOFF configuration. For additional
information on the LED1/REGOFF pin and the disabling of the internal 1.2V regulator (power
sequencing requirements, etc.), refer to the LAN8740A/LAN8741A Datasheet and
LAN8740A/LAN8741A schematics.
2.2.5 Clock Configuration
The EVB8740/EVB8741 can be clocked via the onboard crystal oscillator or an optional external clock.
Crystal Oscillator (Default)
The 25 MHz crystal Y1 is connected to the internal oscillator of the LAN8740A/LAN8741A. A PLL
circuit in the LAN8740A/LAN8741A generates all the timing required by the PHY.

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External Clock
The EVB8740/EVB8741 can be configured to use an external clock by removing crystal Y1 and resistor
R20. A 25MHz +3.3V signal may then be applied to pin 1 of Y1 (which connects to pin 5 of the
LAN8740A/LAN8741A). Pin 2 of Y1 (which connects to pin 4 of the LAN8740A/LAN8741A) should be
left floating when using an external clock.
2.2.6 LEDs
Note: LED1 and LED2 are located inside the RJ45 connector. LED1 and LED2 may function active-
high or active-low depending on the configuration of the REGOFF and nINTSEL straps,
respectively. Refer to the LAN8740A/LAN8741A Datasheet and LAN8740A/LAN8741A
schematics for additional information.
2.2.7 Test Points
Note 2.1 VDDCR is the internal +1.2V regulated output. When REGOFF is enabled, the internal
1.2V regulator is disabled. In this case, an external 1.2V regulator must be supplied to test
point TP3.
Note 2.2 The LAN8740A/LAN8741A’s VDDIO power may be supplied externally at a voltage other
than +3.3V as described in Section 2.1, "Power," on page 3.
Table 2.3 LEDs
REFERENCE COLOR INDICATION
LED1 Green
Link/Activity
Active when the PHY has established a valid link with a link partner
and blinks when activity is detected.
LED2 Yellow
Speed
Active when a 100BASE-TX link has been established. Inactive when
a 10BASE-T link has been established or during line isolation.
Table 2.4 Test Points
TEST POINT DESCRIPTION CONNECTION
TP1 +3.3V Test Point (Orange) +3.3V
TP2 +5.0V Test Point (Red) +5.0V
TP3 +1.2V VDDCR Test Point (Unpopulated)
(Note 2.1)+1.2V
TP4 Ground Test Point (Black) Ground
TP5 VDDIO Test Point (Purple) +3.3V (Note 2.2)
TP6 nPME Test Point (Unpopulated) nPME (RXD2/nPME/RMIISEL)
TP7 AVDD Test Point (White) AVDD
TP8 AVDD_ETH Test Point (Yellow) AVDD_ETH

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2.2.8 System Connections
Note 2.3 Resistor R11 acts as a pull-up on the MDIO pin. In most situations, the MAC circuitry
provides this pull-up and R11 is not required.
Note 2.4 Pins 11 and 21 of the J1 header must be configured to properly connect to the
nINT/TXER/TXD4 pin of the LAN8740A/LAN8741A. Depending on the configured mode,
nINT or TXER/TXD4, R46 must be depopulated or populated. Refer to Section 2.2.3,
"nINT/TXER/TXD4 Pin Configuration (nINTSEL)," on page 6 for additional information.
Table 2.5 System Connections
PLUG/HEADER DESCRIPTION PART
T1 RJ45 with Integrated LEDs Pulse J0011D01BNL
J1 2x14 MII Header
Note: Refer Table 2.6 to for a full pin list Adam Tech PH2-28-U-A
P1 40-pin Female MII Connector
Note: Refer Table 2.7 to for a full pin list Tyco 5173278-2
Table 2.6 J1 - 2x14 MII Header Pinout
HEADER
PIN DESCRIPTION
HEADER
PIN DESCRIPTION
1nRST 15TXD1
2MDIO(Note 2.3)16TXD2
3MDC 17TXD3
4 RXD3/PHYAD2 18 CRS_DV/COL/MODE2
5 RXD2/RMIISEL 19 CRS
6RXD1/MODE1 20 Ground
7RXD0/MODE0 21 nINT (Note 2.4)
8 RXDV 22 VDDIO
9 RXCLK/PHYAD1 23 +3.3V
10 RXER/RXD4/PHYAD0 24 Ground
11 TXER/TXD4 (Note 2.4) 25 Ground
12 TXCLK 26 Ground
13 TXEN 27 Ground
14 TXD0 28 Ground

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Note 2.5 To use the TXER signal from the MAC, the nINT/TXER/TXD4 pin and R46 must be
configured properly. Refer to Section 2.2.3, "nINT/TXER/TXD4 Pin Configuration
(nINTSEL)," on page 6 for additional information.
2.2.9 Switches
Table 2.7 P1 - 40-Pin Female MII Connector Pinout
PIN DESCRIPTION PIN DESCRIPTION PIN DESCRIPTION PIN DESCRIPTION
1 +5V 11 TXER (Note 2.5)21 +5V 31 GND
2 MDIO 12 TXCLK 22 GND 32 GND
3 MDC 13 TXEN 23 GND 33 GND
4 RXD3 14 TXD0 24 GND 34 GND
5 RXD2 15 TXD1 25 GND 35 GND
6 RXD1 16 TXD2 26 GND 36 GND
7 RXD0 17 TXD3 27 GND 37 GND
8 RXDV 18 COL 28 GND 38 GND
9 RXCLK 19 CRS 29 GND 39 GND
10 RXER 20 +5V 30 GND 40 +5V
Table 2.8 Switches
SWITCH DESCRIPTION FUNCTION
S1 Reset switch When pressed, triggers a board reset.

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2.3 Mechanicals
Figure 2.2 details the EVB8740/EVB8741 mechanical dimensions.
Figure 2.2 EVB8740/EVB8741 Mechanicals
1.450
3.000
Ø0.125
Ø0.125
TOP VIEW
0.200
0.175
0.200
0.175