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Author Topic: Wiznet W5500 - minimal Ethernet board  (Read 1813 times)
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Hi, I need to make minimal simple Ethernet board with Wiznet chip.
Original Arduino shield use W5100, but I want to use powerful and cheaper W5500.
W5500 is about 30% cheaper, more powerful and the main - W5500 have only 48-pin package (w5100 have 80-pins) so it was easier to soldering.
Arduino Wiznet library should support W500 chip:
Code:
Uncomment device(shiel) you want to use.
//Arduino\libraries\Ethernet\utility\w5100.h
#ifndef W5100_H_INCLUDED
#define W5100_H_INCLUDED
//#define W5100_ETHERNET_SHIELD
//#define W5200_ETHERNET_SHIELD
#define W5500_ETHERNET_SHIELD

On wiznet webiste is reference schematic (pdf).
I want to use RJ-45 socket with integrated isolation transformer like this.
Can you please explain me why on schematic are 5 identical capacitors (GND to 3V3)? Is possible to use one big capacitor?
What change must I do when W5500 will work on 5V?

Which parts I can remove? I do not use LED in RJ-45 socket.

W5100:
$3.99
4 TCP/UDP Sockets
16KB RAM Buffer
80-Pin LQFP Package


W5500:
$2.62
8 TCP/UDP Sockets
32KB RAM Buffer
Fast SPI Interface
48-Pin LQFP Package


Thank you.
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Valencia, Spain
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Can you please explain me why on schematic are 5 identical capacitors (GND to 3V3)?

It's not about total capacity, it's about total current response time to transients.

Is possible to use one big capacitor?

Probably not. They did it that way for a reason.
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Can you please explain me why on schematic are 5 identical capacitors (GND to 3V3)? Is possible to use one big capacitor?

They are not identical, they are next to different supply pins - decoupling caps have to be
close to the pins they decouple.  One cap cannot be next to all the pins at once.
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Valencia, Spain
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Can you please explain me why on schematic are 5 identical capacitors (GND to 3V3)? Is possible to use one big capacitor?

They are not identical, they are next to different supply pins

At the top left of the schematic there's five identical caps decoupling the 3V3 line.
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And on the board they are placed next to the various supply pins so each one
is adequated decoupled - they are not identical because they are not in the same place,
and at the speeds involved in decoupling fast logic chips that really matters, the
lumped component model doesn't apply.
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Once again, if you're asking these questions, you're probably not ready to be designing your own Ethernet PCB.  Truly don't mean to offend, but engineering complexity of these devices is a bit higher than an Arduino clone for e.g.  Rolling your own is likely to be a frustrating and expensive endeavor until you have the experience to understand the reference schematic, and how to lay out your board accordingly.

As I posted in this similar thread, if you don't understand these questions, you should probably hold off on the DIY design (for now) and use a pre-built module:

Quote
As a practical skill assessment, are you using jacks with integrated magnetics, or are you using an external isolation solution?  Is it compatible with auto-MDIX?  Will you be using PoE, and if so, does your isolation mechanism provide the appropriate sense resistors?

If you're dead-set on doing this (hey, everyone's gotta learn somehow), make sure you post your design for review before sending away for PCBs.  Also, expect and allow for some duds at first.  You'll get there.
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