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Looking for resources on ESR value and dependance on temp.

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lunren

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ESR issues

Hi,

I'm going to design a LDO, the output capacitor is 0.1uF ceramic capacitor. But I have not the esr value of this capacitor. Who can give me some advice or papers about the esr value and the dependence of esr on temperature?
Thanks
 

huojinsi

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Re: ESR issues

No one knows the detailed value of 0.1uF ceramic capacitor, certainly not except the manufacturer of capacitor. Good manufacturer normally give a curve of ESR change range, so u can refer. But if not, u can estimate ESR, generally the value of ESR is on the order of mΩ.
 

v_c

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Re: ESR issues

You better make sure what the ESR range is because its value is critical. Most LDO manufacturers will specify a range of ESR values that will result in stable operation. So instability can occur if the ESR is too low or too high for different reasons. A good paper that describes this is

"Understanding the stable range of equivalent series resistance of an LDO regulator"
http://focus.ti.com/lit/an/slyt187/slyt187.pdf

You should be able to measure the ESR with an impedance analyzer. If you don't have access to this, look at the techniques described in the following links
http://octopus.freeyellow.com/esr.html
http://www.emcesd.com/tt020100.htm

Best regards,
v_c
 

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