I have a question regarding the use of 0-ohm resistors in electronic circuits. While I know they are commonly used as jumpers to connect different parts of a circuit, I’m curious if there are other applications or benefits to using them.
For example in this MCU circuit there is a 0-ohm resistor in both VDD and VSSA. Could they have other applications in this circuit? If so, is it necessary to use them in my circuit too?
This is full schematic I found in the Internet, if you need
For example in this MCU circuit there is two 0-ohm resistor in both VDD and VSSA.
They are there to disconnect the analog supply for testing/evaluation/etc. Likely reasons include:
It's a leftover from revision 0 of the board that was needed in the R&D phase.
It helps troubleshooting needed on the production line, usually during the initial stages of the product's life cycle.
It helps troubleshooting field failures - whether due to issues with the design, or abuse in the field.
It really depends what you mean when you think them as jumpers.
There are electrical uses and physical uses.
For example, if you are making a one sided PCB and need to cross over some tracks with some method, a 0R will mechanically do that without interfering much with the signal.
In the example you post, there might be electrical reasons based on what the designer was thinking. The 0R resistors can be replaced with other value resistances if necessary, or replaced with ferrite beads if needed. So the 0R can simply be a placeholder for something else and enable you to more easily test or verify or modify the circuit as needed, so you don't have to order a new board immediately if you plan ahead.
For example the VDDA resistor could be turned into a ferrite bead.
It can be impossible to say based on that narrow screeshot if there are other reasons for the resistors.
They may also useful for using them in sectioning the PCB design, and used as a link between analog and digital ground reference planes.
You may find these tricks useful in your design, or you might not. Certainly a design does not require them, you can do without.
However that circuit you show may be a poor example anyway. Usually you would not see a 47 uH inductor between VDD and VDDA supplies of the MCU. Of course a lot of the details like bypass caps are missing from the screenshot.
They can sometimes be used for heat dissipation and then normally in quite large packages. It's common in EX environment designs to do things like that. To spread out heat evenly but also as a fail safe. Metal film resistors are considered to act like fuses: if they fail, they break. Which in case of EX means they can act as a fail-safe, unlike for example diodes which often short upon failure and thereby generate lots of heat in a single spot, which is a very bad thing.
Generally on an incomming supply line, you'll have a fuse, followed by n low ohm resistors, followed by 3 TVS, followed by the voltage regulator.
Another use of zero ohm resistors is "RF jumpers", when you have multiple BoM configurations on RF parts. In such cases it is not sufficient just to remove the components, you must also remove all non-terminated stubs. This can be done by starting each optional RF path with a 0 ohm resistor directly on the original trace, so in case components in that path aren't mounted, neither is the 0 ohm resistor.
