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LAN8720

Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support

SMSC -> Microchip 

Small Footprint RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support

Datasheet

Table 2.1 RMII Signals (continued)

NUM PINS

NAME

SYMBOL

BUFFER

TYPE

DESCRIPTION

Carrier Sense

/ Receive

Data Valid

CRS_DV

1

PHY

MODE2

Operating

Mode 2

Configuration

Strap

VO8

VIS

(PU)

This signal is asserted to indicate the receive

medium is non-idle. When a 10BASE-T packet is

received, CRS_DV is asserted, but RXD[1:0] is

held low until the SFD byte (10101011) is

received.

Note:

Per the RMII standard, transmitted data

is not looped back onto the receive data

pins in 10BASE-T half-duplex mode.

Combined with MODE0 and MODE1, this

configuration strap sets the default PHY mode.

See Note 2.1 for more information on

configuration straps.

Note:

Refer to Section 3.7.2, "MODE[2:0]:

Mode Configuration," on page 31 for

additional details.

Note 2.1

Configuration strap values are latched on power-on reset and system reset. Configuration

straps are identified by an underlined symbol name. Signals that function as configuration

straps must be augmented with an external resistor when connected to a load. Refer to

Section 3.7, "Configuration Straps," on page 31 for additional information.

NUM PINS

NAME

LED 1

Regulator Off

Configuration

Strap

1

Table 2.2 LED Pins

SYMBOL

LED1

REGOFF

BUFFER

TYPE

DESCRIPTION

O12

IS

(PD)

Link activity LED Indication. This pin is driven

active when a valid link is detected and blinks

when activity is detected.

Note: Refer to Section 3.8.1, "LEDs," on

page 37 for additional LED information.

This configuration strap is used to disable the

internal 1.2V regulator. When the regulator is

disabled, external 1.2V must be supplied to

VDDCR.

„ When REGOFF is pulled high to VDD2A with

an external resistor, the internal regulator is

disabled.

„ When REGOFF is floating or pulled low, the

internal regulator is enabled (default).

See Note 2.2 for more information on

configuration straps.

Note:

Refer to Section 3.7.3, "REGOFF:

Internal +1.2V Regulator Configuration,"

on page 32 for additional details.

SMSC LAN8720A/LAN8720Ai

11

DATASHEET

Revision 1.4 (08-23-12)

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