Low, Ultra low, Extremely low capacitors - what is the real difference?

[USER REDACTED]

There is many quality low ESR electrolytic capacitors: Low, Ultra low, Extremely low, extra long life...

What is the real difference if efficiency and durability actually, used to replace old ones in power supplies?

I usually used these currently available with supplier: low or ultra low. Datasheets are not so different.

 

[Tony Stewart]

Extremely low

I suspect the descriptors are relative to a suppliers marketing strategy of their own array of products, as there is no industry spec for these terms.

 

[AnalogKid]

I agree, there are no standards, so the only way to compare products from different manufacturers is through a lot of datasheet comparisons. When comparing different product types from one manufacturer, here are some general observations for any specific capacitance and voltage:

Higher operating temperature means a larger package and higher cost.
Longer lifetime means a larger package and higher cost.
Lower ESR means a larger package and higher cost.

ak

 

[Tony Stewart]

In another thread I commented on ESR, so I thought to include here.

ESR is graded according some formula in each dielectric. You can examine ESR from Tan Delta at 120 Hz or dV/dt for a given value when discharged.

ESR drops when C increases to some extent, but I like to create Figures of Merit when this occurs.

For example comparing the ESR * C product which varies as much as the ESR but is constant within a family of Caps at a fixed voltage and size.
You cannot always guarantee ESR drops with reducing voltage, increasing size, but this is generally true.
The biggest variability is from different dielectrics. These results are self-explanatory and are consistent with why we often used 0.01 uF with bulk electrolytics.

Generally for ESR*C my FoM is;
~ 10 seconds coincides with low ESR,
~ 1 second coincides with very low ESR
~10 ms is extremely low ESR
and <1ms is ultra low ESR.

RC(ms) ESR . . C (uF) Type caps
0.5ms . . 50 mΩ . 0.01 metal film (MF) caps (best)
10 ms typ MF
100ms . . 100Ω . . 1 uF MF general purpose ( poor)
1 s . . . . 100mΩ . . 10 uF Alum Electrolytic (best)
100s . . . 100Ω . . . 100,000uF Double Electric layer Super Caps


Long Life are usually 105'C rated vs lower temp. (85'C)

 

[dr pepper]

Supposedly reliability is the same, except for long life ones, I'm not an expert on these however I think it has something to do with the electrolyte remaining at a neutral ph when the cap is discharged extending the life.
In a high frequency high ripple current application such as an smps a low esr is critical, the ripple current v drop across the esr can blow a cap up, I've done it more than once.

 

[Tony Stewart]

Low ESR reduces Temperature rise & voltage ripple from current pulses or step loads. So it improves both reliability as well as performance.

For a step load, one can estimate the dynamic load regulation (load induce ripple) improvement with low ESR Caps by the ESR ratio source/load.
While the steady state load regulation depends on the source/load DC resistance.