LAN9353 Datasheet, PDF (40/523 Pages) Microchip Technology – Interfaces at up to 200Mbps via Turbo MII

LAN9353
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.
DS00001925A-page 40
 2015 Microchip Technology Inc.