Tolerance rating on a 0 Ohm resistor?

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Discussion Overview

The discussion revolves around the tolerance rating of 0 Ohm resistors, commonly referred to as jumper resistors. Participants explore the rationale behind the 5% tolerance rating, the implications of resistance in practical applications, and the distinction between 0 Ohm resistors and fuses.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the logic of a 5% tolerance on a 0 Ohm resistor, noting that 5% of 0 Ohms remains 0 Ohms and suggesting a fixed tolerance might be more appropriate.
  • Another participant humorously acknowledges the common joke in electrical engineering regarding the tolerance of zero ohm jumpers.
  • It is mentioned that 0 Ohm jumpers are typically manufactured using resistor fabrication techniques, implying that there is a finite resistance associated with them, which may be relevant for certain applications.
  • A participant suggests that the datasheet for a 0 Ohm jumper should provide a practical maximum resistance, and if not, one could use 5% of the next higher resistor value, typically 1 Ohm.
  • One participant asserts that 0 Ohm resistors are not designed to act as fuses, clarifying their use as option straps or grounding paths in PCB designs.
  • Another participant adds that while 0 Ohm resistors are not intended to function as fuses, they can be used in configurations where they may blow under certain conditions, such as short circuits.

Areas of Agreement / Disagreement

Participants express differing views on the purpose and application of 0 Ohm resistors, particularly in relation to their function as fuses. There is no consensus on the appropriateness of the tolerance rating or the best way to express it.

Contextual Notes

Participants note the limitations of using 0 Ohm resistors in applications requiring reliable fusing, highlighting concerns about the construction and potential failure modes.

TheAnalogKid83
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Tolerance rating on a 0 Ohm resistor?

I'm just curious why the zero ohm "jumper" resistors I use have a tolerance rating of 5%. This doesn't really make sense to me because 5% of 0 Ohms is still 0 Ohms. I understand that even a close to ideal conductor is not going to be 0 Ohms, but why do they use a percentage of 0 to show the tolerance rather than say \pm 0.1 Ohms??
 
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also, i just realized you can't really have a +/- on a 0 ohm, but just a + (no negative resistance), just wanted to extinguish that before someone called me out on it :D
 
Yeah, that's an old running joke in EE. Tolerance on a "zero ohm jumper" -- LOL.

But as a practical matter, they do make most 0-Ohm jumpers with resistor fab techniques (well, not the old simple wire jumpers), so there will be some finite resistance associated with the jumper, and maybe for some applications, knowing the resistance will be important. The datasheet should give a more practical resistance maximum for the particular 0-Ohm jumper. If it doesn't, just use 5% of the next higher resistor in the family, usually 1 Ohm.
 
Alright thanks for explaining that, I was afraid it was going to be some complicated statistical explanation :D
 
A zero ohm resistor is a fancy word for a fuse. I admit they look different.
 
capnahab said:
A zero ohm resistor is a fancy word for a fuse. I admit they look different.

Not necessarily, in fact, 0-Ohm jumpers are never used as fuses, AFAIK. They are not built to act as fuses. The are used as option straps, usually, or as optional grounding paths for ESD cofigurability of a final PCB design based on final ESD testing.

A fuse does have a finite, low resistance, with some tolerance. I've used low-current fuses as "blow-able" option straps in products that get configured in production to be an expensive version (fuse unblown) or a cheaper version (fuse blown). I've also used cuttable wire jumpers as cheap configuration straps in products that had multiple personalities, where the option is set once, and must never change (so no DIP switches).

A 0-Ohm SMT resistor would be a poor choice for a fuse, because the current and voltage required to reliably blow it open would not be well constrained by the construction, and because the resulting open would be subject to corrosion and potential healing. Not good.
 
Scusa, I should have said act as a fuse in event of short circuit.
 

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