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I've seen the standard NNX exponential value code where NN are the significant digits and X is the \$10^X\$ exponent such that \$value = N\cdot 10^X\$. For example, 121 means 120 (in some unit).

I've also seen component models like the Coilcraft model 0402CS-1N8 where here N is to be interpreted as a decimal point giving the value 1.8nH...and Murata uses R for decimal point in their capacitors. For example:

so I assumed that, as an industry standard, all alpha-digits in the value code are decimal points.

But then, the world was turned upside in my component parser when I found that Coilcraft has a 0402CS-R10 part where "R10" means 100nH (!) and thus R means "multiply times 10"---which is clearly different from Murata's use of "R" as a decimal point.

I know, manufacturers can do whatever they want with model numbers, they own the naming space---but:

Is there a standard specification for component value naming for RF components like inductors, caps, and RF resistors. If so, can you provide a reference?

Other manufacturer naming conventions:

Caps:

  • AVX: uses "R" for decimal point in pF
  • ATC: uses "R" for decimal point in pF
  • Murata: uses "R" for decimal point in pF
  • Vishay: uses "R" for decimal point in pF

Inductors:

  • AVX: uses "N" for decimal point in nH
  • Murata: uses "N" for decimal point in nH
  • Coilcraft:
    • uses "N" for decimal point in nH
    • uses "R" for decimal point in uH
  • Vishay:
    • uses "N" for decimal point in nH
    • uses "R" for decimal point in uH

... so maybe there is a pattern here with R in uH.

Resistors

  • Vishay and others use "R" for decimal point unless it is in mΩ, in which case they use "L", as in 0L50 meaning 0.5mΩ. Also si units are used, such as 1K0 or 1M0 for 1KΩ or 1MΩ.
  • Here is a good reference for resistor naming:

Would be nice if there is an official reference somewhere that can be relied upon that defines component value codes.

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    \$\begingroup\$ I'd rather thing the Coilcraft not multiplying by 10, but simply a decimal point. If 6R8 is 6.8 uF, R10 would be .10 uF, meaning 0.1 uF or 100nF. Which would say Murata and Coilcraft are similar. \$\endgroup\$
    – Justme
    Jun 21 at 23:09
  • \$\begingroup\$ @Justme, perhaps I misunderstood? You mention uF but the units above are nH and pF. The coilcraft 1N8 is 1.8 nH so are you saying that we should consider the that "R" changes the unit to uH? If Murata's use was uF as well then I like that---but theirs are pF and I'm hoping to find something consistent in the industry to program around. \$\endgroup\$
    – KJ7LNW
    Jun 22 at 0:39
  • \$\begingroup\$ @Justme, indeed, now I understand what you are getting at. Thanks! \$\endgroup\$
    – KJ7LNW
    Jun 22 at 1:12

1 Answer 1

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I think there is at least a common sense for the base unit of a component. For capacitors it is pF, so 102 = 100 pF, 224 = 220 nF, 106 = 10 uF. If the component value needs digits below the base unit, a decimal point is needed but can be overlooked. So "R" is a common, good readable substitute and R10 as a capcitor is 0.1 pF.

For inductors the base unit is µH, e.g. 471 = 470 µH, 683 = 68 mH and R10 = 100 nH in this system.

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  • \$\begingroup\$ Thanks for the common sense for base unit. Working in RF, I always thought of the base unit for inductors as nH, but if uH is the common base unit for inductors in the EE world then this is a really great answer to point that out. Big underscore on base unit for anyone else looking this up! \$\endgroup\$
    – KJ7LNW
    Jun 22 at 0:58

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