LAN9252VSLASHML datasheet(31/329 Pages) MICROCHIP

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 2015 Microchip Technology Inc.

DS00001909A-page 31

LAN9252

4.1

Internal Voltage Regulators

The device contains two internal 1.2 V regulators:

• 1.2 V Core Regulator

• 1.2 V Crystal Oscillator Regulator

4.1.1

1.2 V CORE REGULATOR

The core regulator supplies 1.2 V volts to the main core digital logic, the I/O pads, and the PHYs’ digital logic and can

be used to supply the 1.2 V power to the PHY analog sections (via an external connection).

When the REG_EN input pin is connected to 3.3 V, the core regulator is enabled and receives 3.3 V on the VDD33 pin.

A 1.0 uF 0.1

 ESR capacitor must be connected to the VDDCR pin associated with the regulator.

When the REG_EN input pin is connected to VSS, the core regulator is disabled. However, 3.3 V must still be supplied

to the VDD33 pin. The 1.2 V core voltage must then be externally input into the VDDCR pins.

4.1.2

1.2 V CRYSTAL OSCILLATOR REGULATOR

The crystal oscillator regulator supplies 1.2 V volts to the crystal oscillator. When the REG_EN input pin is connected to

3.3 V, the crystal oscillator regulator is enabled and receives 3.3 V on the VDD33 pin. An external capacitor is not

required.

When the REG_EN input pin is connected to VSS, the crystal oscillator regulator is disabled. However, 3.3 V must still

be supplied to the VDD33 pin. The 1.2 V crystal oscillator voltage must then be externally input into the OSCVDD12 pin.

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