LAN7430 datasheet(21/77 Pages) MICROCHIP

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DS00002631D-page 21

LAN7430/LAN7431

Auxiliary Voltage

Detect

VAUX_DET

VIS

(PD)

Auxiliary Voltage Detection

The VAUX_DET is used to indicate when PME from

D3cold is supported.

When tied to VSS, PME from D3cold is not supported.

The weak pull-down will create a logic low when plugged

into a system board that does not support the delivery of

the auxiliary voltage (the auxiliary voltage connection is

floating).

When the device is powered exclusively from auxiliary

voltage, this pin is tied to the auxiliary voltage (3.3V) to

indicate PME from D3cold is supported.

When the device is powered from a multiplexed main

voltage / auxiliary voltage, this pin is tied to the auxiliary

voltage (3.3V) to indicate PME from D3cold is supported

and to monitor the presence of the auxiliary voltage.

Note:

If alternate usage of this pin (GPIO3, LED3 or

TCK) is enabled, the pull-down is disabled and

the input value of the pin is overridden to a low

value.

Since this pin is shared with GPIO3, LED3 and TCK, a

series resistor is recommended to prevent an accidental

conflict with the auxiliary voltage. This resistor must be

low enough in value to override the on chip pull-down.

Crystal / Oscillator / External Reference Clock

Crystal / Oscilla-

tor / External Ref-

erence Clock

Input

ICLK

When using a 25MHz crystal, this input is connected to

one lead of the crystal.

When using a 3.3V oscillator or external reference clock,

this is the input from the clock source.

The crystal, oscillator, or external reference clock should

have a tolerance of ±50ppm.

Crystal Output

OCLK

When using a 25MHz crystal, this output is connected to

one lead of the crystal.

When using an oscillator or external clock source, this pin

is not connected.

EEPROM

EEPROM Chip

Select

EECS

VO12

(PD)

This pin drives the chip select input of the external

EEPROM.

Note:

The internal pull-down holds a low on the

output pin during reset.

TABLE 3-3:

PIN DESCRIPTIONS (CONTINUED)

Name

Symbol

Buffer

Type

Description

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