LAN89730 datasheet(101/218 Pages) MICROCHIP

101 / 218 page

 2013-2015 Microchip Technology Inc.

DS60001348A-page 101

LAN89730

• Hardware Configuration Register (HW_CFG)

• LED General Purpose IO Configuration Register (LED_GPIO_CFG)

• General Purpose IO Wake Enable and Polarity Register (GPIO_WAKE)

4.9

Device Clocking

The device requires a fixed-frequency 25 MHz clock source. This is typically provided by attaching a 25 MHz crystal to

the XI and XO pins. The clock can optionally be provided by driving the XI input pin with a single-ended 25 MHz clock

source. If a single-ended source is selected, the clock input must run continuously for normal device operation.

Internally, the device generates its required clocks with a phase-locked loop (PLL). It reduces its power consumption in

several of its operating states by disabling its internal PLL and derivative clocks. The 25 MHz clock remains operational

in all states where power is applied.

4.10

Device Power Sources

The device may be soft powered by the USB bus or self powered via external power supplies. The following external

3.3 V power supplies are required when power is not being furnished by the USB bus:

• VDD33IO, VDD33A

The device includes an internal 1.2 V regulator which provides power to the internal core logic. This regulator may be

optionally disabled if an external 1.2 V power source is available. The internal core regulator is controlled via the

CORE_REG_EN pin. When disabled, +1.2 V must be supplied to the device by an external source. Refer to Chapter

3.0 for information on proper power connections when enabling or disabling the internal core regulator.

4.11

Power States

The following power states are featured.

• NORMAL (Unconfigured and Configured)

• Suspend (SUSPEND0, SUSPEND1, SUSPEND2, and SUSPEND3)

Figure 4-29 illustrates the power states and allowed state transitions.

FIGURE 4-29:

POWER STATES

Note:

It is not possible to transition from SUSPEND2 to NORMAL Configured if SUSPEND2 was entered via a

transition from NORMAL Unconfigured.

NORMAL

(Configured)

SUSPEND0

SUSPEND1

SUSPEND2

USB Resume ||

PHY Linkup ||

WOL || GPIO

USB Suspend

USB Resume ||

GPIO

USB Suspend

USB Resume ||

Energy Detect ||

GPIO

USB Suspend

POR || nRESET ||

USB Reset || SRST

NORMAL

(Unconfigured)

Configured

Deconfigured

USB Resume ||

GPIO

USB Suspend

SUSPEND3

USB Suspend

USB Resume ||

PHY Linkup ||

Frame Rec’d || GPIO

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