Understanding Ceramic Capacitor Temp-Coefficients


#1

A common question when looking at ceramic capacitors is what do the temperature coefficient numbers/letters mean? These numbers will generally break down to a temperature range and the variation in capacitance over that specific range. The first thing you need to understand with what standard and class you are looking at. These are split between the International Electrotechnical Commission (IEC) and the Electronic Industries Alliance (EIA)

Here is a chart on the different classes and definitions:

IEC/EN 603841 &
IEC/EN 60384-8/9/21/22
EIA RS-198
Class 1 ceramic caps offer high stability and low losses for resonant circuit applications Class I ceramic caps offer high stability and low losses for resonant circuit applications
Class 2 ceramic capacitors offer high volumetric efficiency for smoothing, by-pass, coupling and decoupling applications Class II (or written class 2) ceramic capacitors offer high volumetric efficiency with change of capacitance lower than −15% to +15% and a temperature range greater than −55 °C to +125 °C, for smoothing, by-pass, coupling and decoupling applications
Class 3 ceramic capacitors are barrier layer capacitors which are not standardized anymore Class III (or written class 3) ceramic capacitors offer higher volumetric efficiency than EIA class II and typical change of capacitance by −22% to +56% over a lower temperature range of 10 °C to 55 °C. They can be substituted with EIA class 2- Y5U/Y5V or Z5U/Z5V capacitors
Class IV (or written class 4) ceramic capacitors are barrier layer capacitors which are not standardized anymore

With class definitions understood you can look how the temperature coefficients break down.

Class 1 per EIA-RS-198

Temperature coefficient α
10-6 /K Letter code
Multiplier of the temperature
coefficient Number code
Tolerance of the temperature
coefficient Letter code
C: 0.0 0: -1 G: ± 30
B: 0.3 1: -10 H ± 60
L: 0.8 2: −100 J: ±120
A: 0.9 3: −1000 K: ±250
M: 1.0 4: +1 L: ±500
P: 1.5 6: +10 M: ±1000
R: 2.2 7: +100 N: ±2500
S: 3.3 8: +1000
T: 4.7
V: 5.6
U: 7.5

Class 1 per IEC/EN 60384-8/21 and EIA-RS-198

Ceramic names Temperature coefficient α 10-6 /K α-Tolerance 10-6 /K Sub-class IEC/ EN- letter code EIA letter code
P100 100 ±30 1B AG M7G
NP0 0 ±30 1B CG C0G
N33 −33 ±30 1B HG H2G
N75 −75 ±30 1B LG L2G
N150 −150 ±60 1B PH P2H
N220 −220 ±60 1B RH R2H
N330 −330 ±60 1B SH S2H
N470 −470 ±60 1B TH T2H
N750 −750 ±120 1B UJ U2J
N1000 −1000 ±250 1F QK Q3K
N1500 −1500 ±250 1F VK P3K

Looking at these charts you see, an “NP0” capacitor with EIA code “C0G” will have 0 drift, with a tolerance of ±30 ppm/K, while an “N1500” with the code “P3K” will have −1500 ppm/K drift, with a maximum tolerance of ±250 ppm/°C.

Note that the IEC and EIA capacitor codes are industry capacitor codes and not the same as military capacitor codes.

Class 2 per EIA RS-198

Letter Code for Low Temp Number Code for High Temp Letter code for change of capacitance
over the temp range
X = −55 °C (−67 °F) 4 = +65 °C (+149 °F) P = ±10%
Y = −30 °C (−22 °F) 5 = +85 °C (+185 °F) R = ±15%
Z = +10 °C (+50 °F) 6 = +105 °C (+221 °F) S = ±22%
7 = +125 °C (+257 °F) T = +22/−33%
8 = +150 °C (+302 °F) U = +22/−56%
9 = +200 °C (+392 °F) V = +22/−82%

For instance, a Z5U capacitor will operate from +10 °C to +85 °C with a capacitance change of at most +22% to −56%. An X7R capacitor will operate from −55 °C to +125 °C with a capacitance change of at most ±15%.

Here are some common Class 2 configurations:

  • X8R (−55/+150, ΔC/C0 = ±15%),
  • X7R (−55/+125 °C, ΔC/C0 = ±15%),
  • X6R (−55/+105 °C, ΔC/C0 = ±15%),
  • X5R (−55/+85 °C, ΔC/C0 = ±15%),
  • X7S (−55/+125, ΔC/C0 = ±22%),
  • Z5U (+10/+85 °C, ΔC/C0 = +22/−56%),
  • Y5V (−30/+85 °C, ΔC/C0 = +22/−82%),

Class 2 per IEC/EN 60384-9/22

Code for capacitance change Max capacitance change
ΔC/C0 at U = 0
Max capacitance
change
ΔC/C0 at U = UN
Code for temp range Temp Range
2B ±10% +10/−15% 1 −55 … +125 °C
2C ±20% +20/−30% 2 −55 … +85 °C
2D +20/−30% +20/−40% 3 −40 … +85 °C
2E +22/−56% +22/−70% 4 −25 … +85 °C
2F +30/−80% +30/−90% 5 (-10 … +70) °C
2R ±15% 6 +10 … +85 °C
2X ±15% +15/−25% - -

In some cases it is possible to translate the EIA code into the IEC/EN code. Slight variations can occur, but normally are tolerable.

  • X7R correlates with 2X1
  • Z5U correlates with 2E6
  • Y5V similar to 2F4, aberration: ΔC/C0 = +30/−80% instead of +30/−82%
  • X7S similar to 2C1, aberration: ΔC/C0 = ±20% instead of ±22%
  • X8R no IEC/EN code available

What is X8L Temp Coefficient?
#2

Thanks for the tables!

Two things I’d add:

  1. It’s probably more correct to call it a temperature “characteristic” since the term “coefficient” usually implies some sort of linear-ish relationship. Outside of the class 1 devices, the capacitance vs. temperature relationship isn’t all that linear:

  2. In speaking about a “max capacitance change” it should be noted that this refers to the effects of TEMPERATURE ONLY, measured under very specific test conditions. Other factors, most notably DC bias effect and aging, can cause enormous changes in observed capacitance.


Why ceramic capacitors may seem out of spec, but aren’t
#3

As I understand it, the TCC is independent of tolerance. That would mean that one would need to add the tolerance to the TCC when performing a worst case circuit analysis. Is that right?


#4

That would be correct. TCC is a function of the material the capacitor is made of; tolerance is a function of manufacturing imprecisions as compared to the nominal/ideal standard for that part. The two can have similar impacts on a circuit, but they’re distinct effects that have to be accounted for separately.