Dual Resistor Wattage Rating

[mth5044]

Does anyone know what it means when resistors have dual wattage ratings? Data sheet for reference:

https://www.vishay.com/docs/31015/ccf55.pdf

At first I thought it was two product lines, a 1/4W and a 1/2W, but upon further reading and trying to find the product online, it appears they are the same thing. There's no identifier in the part number to separate the two wattage's and the only reported difference is the 'stability' at each wattage. I'm not even sure what stability means in this regard - is it in reference to the stability of the ohms depending on the heat it's putting off?

I was planning on using these as 1/2W, otherwise I wouldn't care too much. They are $0.04 on Arrow. Their sorting system is abysmal (at least on my browser), there's probably cheaper ones on there, but I can't take it any more.

Grazie

[vigilante397]

It is a little ambiguous, but if I understand correctly they will just last longer run at 1/4W and below. If you go down a couple pages you'll see that the expected life is different at 1/2W than it is at 1/4W. Just a thought though, not positive.

[GibsonGM]

It is a little ambiguous, but if I understand correctly they will just last longer run at 1/4W and below. If you go down a couple pages you'll see that the expected life is different at 1/2W than it is at 1/4W. Just a thought though, not positive.

Yup.   And the tolerance will change, being better at 1/4W.   I think it's odd, too, but that's what it is.

[mth5044]

Thanks guys. Looks like stability is interchangeable with 'life'. Strange. Well hopefully 1% life is good enough! Some of the Xicon stuff has 'load life' of 1.5%, so I'll roll the dice.