Ethernet phy crystal oscillator in STM32H7xxI-EVAL

[IMor.1]

Hi

I design a board based on the STM32H7xxI-EVAL, the ethernet PHY is LAN8742A-CZ-TR and according to its the datasheet the crystal specification the drive level need to be 300uW but the maximum drive of X53T-C20SSA-25.000MHz level is only 100uW.

Did you have any problem? or is it on purpose?

[TDK]

> according to its the datasheet the crystal specification the drive level need to be 300uW

Are you sure? Directly from the datasheet:

It is recommended that a crystal utilizing matching parallel load capacitors be used for the crystal input/output signals (XTAL1/XTAL2). Either a 300 µW or 100 µW 25 MHz crystal may be utilized. The 300 µW 25 MHz crystal specifications are detailed in Section 5.7.1, "300 µW 25 MHz Crystal Specifications". The 100 µW 25 MHz crystal specifications are detailed in Section 5.7.2, "100 µW 25 MHz Crystal Specifications".

A series resistor is required in one configuration.

[Neuromod]

Have you checked the Nucleo boards that use the Microchips LAN8742A? For instance, the NUCLEO-H563ZI uses a NDK NX2016SA Crystal, that supports a max drive level of 200 uW, but without a series resistor (0R). Is this a poor design or am I missing something?