# How large is the ESR for capacitor on-chip?

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#### surianova

hi!

as i know, the external capacitor normally have the ESR resistor in series
with capacitor. How about the capacitor in the chip or on-chip capacitor, do they have ESR resistor?

#### gevy

##### Full Member level 6
Re: ESR

Yes, on-chip capacitor have ESR

#### surianova

Re: ESR

gevy said:
Yes, on-chip capacitor have ESR
normally how much the ESR for capacitor on chip?

#### v_c

Re: ESR

Usually, the manufacturer will specify the ESR of a capacitor or provide a graph in the datasheet for the device. Some capacitors (like ceramics) have such a low capacitance that the manufacturer will not even put numbers on datasheets.

It is always good to remember that the ESR is a function of temperature, so if your application has wide temperature specifications, ESR variation can cause variations in performance. A good example of this is switching power supplies and also in low dropout linear regulators (LDOs).

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#### huojinsi

##### Full Member level 5
Re: ESR

surianova wrote:
normally how much the ESR for capacitor on chip?
Generally the value of ESR is on the order of mΩ.

#### v_c

Re: ESR

Yes, I think chip capacitors can have pretty low ESR values.
But normal (discrete) capacitors can have ESR values in $\Omega$s. For example, it is not uncommon to find electrolytic capacitors that will have ESR value of $3-4\Omega$ at room temperature $\approx 25{}^{\circ}C$. The value of the ESR approximately doubles when you go to low temperature extremes like $-40{}^{\circ}C$. So things that work beautifully at room tempeature might suddenly give you trouble at cold temperatures.

Best regards,
v_c

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