What does it means:  Absolute Resistor Value Temperature Drift - Page 1
Forum section: electronics / general

author: nour
author_rank: Frequent Contributor
timestamp: June 05, 2017, 04:25:23 pm
content: I am aware of the meaning of temperature drift but I don't think I understand the meaning of "Absolute"?Also, I don't see this term in other devices like op amps or voltage reference! which is confusing, is it something related to resistors only?

author: pitagoras
author_rank: Regular Contributor
timestamp: June 05, 2017, 04:27:24 pm
content: I would say it is how many ohms a resistor changes for every degree of change

author: Muxr
author_rank: Super Contributor
timestamp: June 05, 2017, 04:52:04 pm
content: Absolute is opposite of Relative.Quotehttp://www.vishaypg.com/docs/63517/FACTS-121.pdfSo absolute is as it says the absolute drift of a resistor, not the relative drift between resistors of the same type (which might be lower if you expect resistors of the same composition to have similar drifts). At least that's how I am parsing it.

author: nour
author_rank: Frequent Contributor
timestamp: June 05, 2017, 06:24:43 pm
content: Quote from: pitagoras on June 05, 2017, 04:27:24 pmIt would still be the same if we omit the word absolute refer to any opamp datasheet and look at Vos drift, there is no absolute there!Quote from: Muxr on June 05, 2017, 04:52:04 pmSo basically, the "Absolute" term means the drift relative to the resistor as an entity not relative to other resistors? well, why don't we see the same term in other devices datasheets? and why not just say drift and everyone will know we are talking about the resistor itself and say relative drift if we are talking about resistor among others?

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: June 05, 2017, 06:50:14 pm
content: Long ago you'd see the term "absolute ohms" as opposed to "international ohms". I wonder if it's a carryover of some sort.

author: pitagoras
author_rank: Regular Contributor
timestamp: June 05, 2017, 07:11:43 pm
content: Quote from: nour on June 05, 2017, 06:24:43 pmIt would help if you show us the context.Absolute might indicate that it is expressed in ohms rather than ppm (i.e. relative to the resistor value).

author: nour
author_rank: Frequent Contributor
timestamp: June 05, 2017, 07:16:58 pm
content: Quote from: pitagoras on June 05, 2017, 07:11:43 pmfrom LT5400 Datasheet:QuoteLT5400It is indicated in ppm not in ohms!Which lead me to ask, which is important? the relative or the absolute drift?

author: pitagoras
author_rank: Regular Contributor
timestamp: June 05, 2017, 07:57:01 pm
content: Quote from: nour on June 05, 2017, 07:16:58 pmWhat I understand in this case is that the measured value of each resistor can drift at 8ppm/C, but the ratio of the resistors are within 0.2ppm/C. I.e they drift "together".

author: Muxr
author_rank: Super Contributor
timestamp: June 05, 2017, 08:43:15 pm
content: LT5400 is a quad matched resistor network, so that's why they feel the need to call it absolute to let you know that they mean absolute not compared to the other resistors in the network. There is no need to call something absolute when talking only about one resistor (as opposed to a matched resistor network).

author: nour
author_rank: Frequent Contributor
timestamp: June 05, 2017, 10:11:47 pm
content: Quote from: Muxr on June 05, 2017, 08:43:15 pmIn Vishay datasheetVHP100They have mentioned thisAbsolute resistance change (window):VHP100 < 60 ppm (- 55 °C to + 125 °C)VHP101 < 10 ppm (+ 15 °C to + 45 °C)What is the meaning of "absolute" in this datasheet? There is no mention for a resistors array(which is obvious!) to have a need to say absolute!And what does window means?They have mentioned also it is zero TCR in the title !!!! Why if they later said 10 ppm

author: pitagoras
author_rank: Regular Contributor
timestamp: June 06, 2017, 06:33:49 pm
content: Quote from: nour on June 05, 2017, 10:11:47 pmIt is explained in the data sheet. The tcr in ppm/C is nearly zero, so instead of that they define window as the maximum variability in the whole range of operating temperature (which is 60ppm)