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Tolerances on a 0 ohm resistor...
Holes Flow:
Experts,
In terms of lowest and highest value range of 5%, what should my expectations reasonably be?
:)
RoGeorge:
Read the datasheet of the 0\$\Omega\$ resistors, and you'll find the resistance is not zero, but a very low value that is specified in the datasheet. In this case, that specified small value has 5% tolerance.
Later edit:
--- Quote from: Holes Flow on May 31, 2020, 10:49:36 pm ---In terms of lowest and highest value range of 5%, what should my expectations reasonably be?
--- End quote ---
- highest value is to be found in the resistor's datasheet
- lowest value is not specified in the datasheet, but it is supposed that that type of zero resistors to be used as a jumper, and not as a resistor with a well specified value.
edpalmer42:
And 5% of 0 is .......
OMG, what's -5% of zero!! :o We always thought that the little black craters in boards were due to resistors burning up. Maybe they were zero ohm resistors that drifted down in value and created mini black holes!!
Wolfgang:
--- Quote from: Holes Flow on May 31, 2020, 10:49:36 pm ---Experts,
In terms of lowest and highest value range of 5%, what should my expectations reasonably be?
:)
--- End quote ---
You could select those with a -5% tolerance out and sell them as energy sources :)
Seriously: Your PCB tracks probably have a resistance in the same range, i.e., tolerances do not really matter.
Cerebus:
--- Quote from: RoGeorge on May 31, 2020, 11:07:41 pm ---Read the datasheet of the 0\$\Omega\$ resistors, and you'll find the resistance is not zero, but a very low value that is specified in the datasheet. In this case, that specified small value has 5% tolerance.
--- End quote ---
I have never seen that. Every data sheet that I've ever seen that specifies a 0 ohm resistor gives only a maximum value, not a specific, toleranced, value. e.g. The reel of Yageo 0805s I have here, the data sheet has "Zero Ohm Jumper < 0.05 Ω". Actually I measured those, out of curiosity, a while back and they came in around the 20 milliohm region, which is excellent.
It would actually be quite dangerous from the manufacturers' point of view to give a specific value with a 5% tolerance because some sod who doesn't understand the difference between a "zero" ohm resistor intended for use as a jumper and a 50 milliohm resistor intended to be used as a resistor would use it as a resistor and then moan at you, or sue you, when their huge production batch doesn't work because you supplied excellent "zero" ohm resistors that were only 1 miiliohm. It would also be prohibitively expensive to test zero ohm resistors to a 5% tolerance of a specific value on a production line for sub 1 cent components. As anyone who's tried taking accurate resistance measurements below 1 ohm will tell you, it's not easy or quick.
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