Is this diode fine for the RESET pin?

[FreshmanNewbie]

I'm using this KSZ8041MLLI device and this is its Hardware checklist

I'm using the MII Interface between this PHY and the MAC Controller (STM32 MCU) on the same board.

My question is whether we require length matching of the MII signals between these two devices? It is not mentioned in the datasheet? Also, it would be helpful for me if you can tell for which (x)MII interface signals do we require length matching?

 

[FreshmanNewbie]

I'm using this KSZ8041MLLI device and this is its Hardware checklist

I'm using the MII Interface between this PHY and the MAC Controller (STM32 MCU) on the same board.

As per figure 7-14 on page 54 of the datasheet, I am connected my reset to the MCU through the below circuit:



This is the diode that I am using. Is this dual diode configuration fine or should I use a single diode itself? Also, I am not sure on where to connect the other end of the schottky diode? Can someone give some advice on this.

 

[KlausST]

Hi,

Why in your datasheet it says "150mA"?
What is R82 for (to GND)?
Why did you choose BAS70-04? (If you are worried about the second diode)
Why not BAS70? Why not BAS70-06?

Klaus

 

[dick_freebird]

I'd put both of the mystery anodes to Gnd if you are
not aware of any signal use.

Peculiar that the pullup resistor and filter cap have "DNF"
values. I'm aware of "DNI" (Do Not Install).

You want a Schottky with a low enough Vf that you make
an in-spec VIL at the receiving IC (according to its ratings)
from a barely-in-spec reset level (which may be TTL if a
legacy system).

Could be a bind, with TTL VOL at 400mV and VIL often being
20% of VDD (so 0.66V at nominal, 0.7 at high 3.3V) and
the Schottky Vf occupying the vanishing middle ground.
More likely this scheme was for old TTL where VIL(max)
was 0.8-ish and threshold, about 1.4V with no Idd penalty
for kissing the limit (unlike CMOS, where there will be
shoot-through current in the input buffers all across the
VILmax-VIHmin range).