What is the unit for capacitor temperature coefficient?

[snee]

capacitor temperature coefficient

Unit for temperature coefficient, tc for capacitor is per degree Celcius.
However most of the datasheet that i found shows unit with
1) % Δ Cmax
2) ppm/degree Celcius
an someone give an example of calculation to convert it to per degree Celcius and what the unit means?

What is the nominal temperature for the value on datasheet?

Thanks.

 

[Kral]

temperature coefficient ppm

snee,
Both % and ppm are dimensionless quantities, so the units in both cases are per deg C. However, you must apply a scale factor to get Capacitance per deg C.
.
Assume that Cnom is the nominal capacitance. Then to convert %/Deg C to Capacitance per Deg C, you would use
Capacitance per Deg C = Cnom X % / 100
.
To convert ppm per Deg C to Capacitance per Deg C, you would use
Capacitance per Deg C = Cnom X ppm / 1000000.
.
ppm stands for "parts per million"
.
Cnom is usually specified at 25 Deg C.
Regards,
Kral

 

[snee]

unit for temperature coefficient

Does that means the unit for % Δ Cmax is the same as %/degree Celcius?

Thank you very much Kral.

 

[Kral]

unit of temperature coefficient

snee,
No. It just means that they are what I like to call "Labels of Convenience" rather than true units. 1 ppm/(deg C) is equal to (100/1000000) %/(deg C) = 1/10000 %/(deg C) .
.
Other examples of "Labels of Convenience" are Degress (of angle) and Radians. They are both measures of rotation, but they are dimensionless and are not equal. A degree cna be thought of as an angle equivalent to 1/360th of the way around the circumference of a circle. A radian can be thought of as the angle subtendeded by moving a distance around the circumference of a circle equal to the radius of the circle. It has the units of distance/distance, or, in other words, it is dimensionless.
Regards,
Kral

 

[snee]

ppm capacitance

I understand what u mean and the unit for ppm/(degree Celcius) and %/(degree Celcius) but i just can't see how to equate the unit of % Δ Cmax to per degree Celcius.

What does % Δ Cmax means?
Δ Cmax means changes in Celcius or per degree Celcius?

Thnaks.

 

[Kral]

capacitor temp coefficient

snee,
I made the (perhaps unwarranted) assumption that % ΔCmax means that the capacitance will change by at most 1% for each degree C change in temperature.
I have never seen this nomenclature on a capacitor data sheet. What manufacturer and part number are you referring to? I'd like to take a look at the data sheet.
Regards,
Kral

 

[snee]

capacitor changes temperature

The datasheet or more to catalog is from Novacap.



Below is the link where i get the pdf file:
http://www.novacap.com/product_page.php?pk=PR14

Thank you again.

 

[Kral]

what is ppm per degree celcius

snee,
It appears that the expression "% Δ Cmax" refers to the maximum % change in capacitance that can occur over the specified temperature range. In this case, the capacitance change can vary from +15% to -65% over the temperature range of -55 deg c to +200 deg C. This is the first time that I have seen the temperature tolerance expressed in this manner.
Regards,
Kral