LAN8740A Datasheet, PDF (38/136 Pages) Microchip Technology – Small Footprint MII/RMII 10/100 Energy Efficient Ethernet Transceiver with HP Auto-MDIX and flexPWR® Technology

LAN8740A/LAN8740Ai
3.8.1.4 LED2/nINT/nPME Usage with nINTSEL Disabled
When the LED2/nINT/nPME/nINTSEL pin is low during reset, the nINT/TXER/TXD4 pin is configured to function as
TXER/TXD4. After the deassertion of reset, this pin will first function as LED2. Upon configuration, it can function as
nINT or nPME. Figure 3-10 illustrates the steps required to program the LED2 pin as nINT or nPME with nINTSEL dis-
abled.
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.
FIGURE 3-10:
LED2/nINT/nPME WITH nINTSEL DISABLED
nRST
LED2/nINT/
nPME/nINTSEL
WUCSR[12:11]
Link Speed
00b
nINT/nPME
01b/10b
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 3-11
details the LED1 polarity for each REGOFF configuration.
FIGURE 3-11:
LED1/REGOFF POLARITY CONFIGURATION
REGOFF = 1 (Regulator OFF)
LED output = Active Low
VDD2A
REGOFF = 0 (Regulator ON)
LED output = Active High
LED1/REGOFF
10K
~270 
~270 
LED1/REGOFF
Note: Refer to Section 3.7.4, "REGOFF: Internal +1.2 V Regulator Configuration" for additional information on
the REGOFF configuration strap.
DS00001987A-page 38
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