# What is the impedance value that means it is a low ESR capacitor?

I need to select a 300uF capacitor and it is mentioned in the datasheet that it should be a Low ESR capacitor. However, it is not mentioned the impedance range or how much it should be.

How can I know if the impedance value is low or high ? If I find a capacitor with 0.5 ohm impedance at 100kHz, is it Low or High ?!

• link to the datasheet, we can't guess the context – Neil_UK Aug 4 '16 at 8:13
• depends on your application. pls share the ref. docs – User323693 Aug 4 '16 at 8:14

In general, the impedance of a capacitor with an ESR can be computed as $$\dot{Z}_c = ESR - i\frac{1}{\omega C}.$$ Then, knowing the frequency at which the total impedance is given (f = 100 kHz), just solve the equation for ESR.