Hello to all.I want to design below circuit in Altium.
Actually I have a circuit like below belong to Mini-DK2 board.
Two questions:
1- what does it mean "0R" here?
2-What exactly kind of crystal I should use?
Thanks.
- A zero ohm resistor
- It totally depends on the design. Look up the LAN8720A and see what crystal it should have.
What is the meaning of zero ohm resistor?Do we have it?
It is a piece of wire in the shape of a resistor. It is used anywhere that you need to have the option of installing a different resistor in the future or you need a wire to jump over other traces on the board.
The resistor shape is useful to an automated pick-and-place machine, that already knows how to place resistors.
You mean , if I don't use it at all, it is no problem?
How about the inductor, Is it the same as this?
No you need the 0R resistor.
He's telling you it is used a conductor... like a wire jumper.
The label 0R does not mean optional. It means think of it as a wire. A resistor "shape" with no resistance value.
As a general rule, Ethernet parts use 25MHZ crystal... This is why though... the first thing you should be doing is finding a datasheet for LAN8720A to verify the xtal value. It will be a critical component.
The inductor is very specific. You will need one that does what this does... either as a separate part or integrated into the connector... as shown. (A typical Ethernet "coil" arrangement)
(I finally opened the diagram in the first post.)
R33 is a connection between the circuit ground and the case (or shield) ground. It is optional in the sense that you might sometimes want the shield on the ethernet connector grounded to the earthed metal case of your device and not connected to the circuit.
If you are putting this into to a metal case with an earth wire connected to a 3-pin plug plugged into the wall, then don't fit R33. If it's battery operated or only has a 2-pin plug, then install R33. You may use a blob of solder or a piece of wire instead of buying a zero-ohm resistor.
Lantronix has some good tips on earthing and grounding ethernet devices. They suggest using a capacitor in this position, so high frequency noise is common to both nets but still allows a DC voltage to exist without causing current to flow through this "resistor".
How about the 0R inductor.
If I ignoring it , does it make me problem?
Thanks.
Hi, what is your electronics and hardware experience?
Tom.... 
leoncorleone:
How about the 0R inductor.
If I ignoring it , does it make me problem?
Thanks.
Yes
TomGeorge:
Hi, what is your electronics and hardware experience?Tom....
Sod all is my guess.
Actually I am new in it.why?
Actually I mean if I do short circuit insted of the inductor,Does it make me problem.?
I mean what kind of problem?
On surface-mount component boards, the "0R" is a chip which is essentially that - a zero ohm resistor - which is placed in exactly the same manner as a resistor with automated pick-and-place equipment.
That inductor is often a wire link threaded through one or more ferrite beads, or a number of holes in a single bead.
leoncorleone:
I mean what kind of problem?
Isolation of noise, usually.
Today I went shopping to buy it , but there wasn't anywhere.
Can I replace it with something else?
Inductors are measured in Henries, not Ohms, which you have probably found in your shopping expedition. It looks like a mistake on the circuit. Can you contact the original designer?
It will probably work with a wire link in place of the inductor. Ethernet uses such high frequencies that noise and radiation is always a problem. The actual layout on the PCB is very important to minimize these problems. From just that diagram, you can't tell where to put it on the board even if you could guess an appropriate value.
This is not a beginner project you are attempting here. Your overall chance of success with the knowledge you have demonstrated so far is very low.
leoncorleone:
Actually I am new in it.why?
Actually I mean if I do short circuit insted of the inductor,Does it make me problem.?
Think about it. Someone designed a circuit that contains a component that you can remove and have no problems! Why would anyone ever do that? Or are you smarter than the person who designed the circuit and know it is not needed? Again this is unlikely given the insight you have shown.
That inductor is designed to separate and decouple interactions between one side of the circuit and the other. Remove it and the specification of what you are making drops. Maybe it even drops to the point of not working but in any case it will affect the reliability of the circuit.
What you are attempting to build is way out of your league.