LAN8742AI-CZ datasheet(38/124 Pages) MICROCHIP

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LAN8742A/LAN8742Ai

DS00001989A-page 38

 2013-2015 Microchip Technology Inc.

3.8.1.4

LED2/nINT/nPME Usage with nINTSEL Disabled

When the LED2/nINT/nPME/nINTSEL pin is low during reset, the nINT/REFCLKO pin is configured to function as REF-

CLKO. After the deassertion of reset, this pin will first function as LED2. Upon configuration, it can function as nINT or

nPME. Figure 3-13 illustrates the steps required to program the LED2 pin as nINT or nPME with nINTSEL disabled.

In this configuration, it is not recommended to connect an LED to this pin. Because this pin is active high, the LED will

be lit while waiting for a WoL event.

3.8.1.5

REGOFF and LED1 Polarity Selection

The REGOFF configuration strap is shared with the LED1 pin. The LED1 output will automatically change polarity based

on the presence of an external pull-up resistor. If the LED1 pin is pulled high to VDD2A by an external pull-up resistor

to select a logical high for REGOFF, then the LED1 output will be active low. If the LED1 pin is pulled low by the internal

pull-down resistor to select a logical low for REGOFF, the LED1 output will then be an active high output. Figure 3-14

details the LED1 polarity for each REGOFF configuration.

FIGURE 3-13:

LED2/nINT/nPME WITH nINTSEL DISABLED

FIGURE 3-14:

LED1/REGOFF POLARITY CONFIGURATION

Note:

Refer to Section 3.7.3, "REGOFF: Internal +1.2 V Regulator Configuration" for additional information on

the REGOFF configuration strap.

nRST

LED2/nINT/

WUCSR[12:11]

Link Speed

nINT/nPME

00b

01b/10b

nPME/nINTSEL

LED1/REGOFF

~270



REGOFF = 0 (Regulator ON)

LED output = Active High

~270



VDD2A

REGOFF = 1 (Regulator OFF)

LED output = Active Low

LED1/REGOFF

10K

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