Derating of resistor/capacitor

** Yawn - more Google Groper crap !!

** What does this arrogant, GG wog idiot think the term "derate" means ????

Maybe this uppity DARKIE would care to en-LIGHTen us all.

Don't hold your breath.

...... Phil

Pon, In the aerospace industry it is common to derate resistors and capacitors to 70% of their room temperature power, voltage ratings respectively. This varies somewhat depending on the type of component. All resistors have a temperature derating spec. It is usually specified as something like "Derate X% per deg C above 70 Deg C". For more on derating of components, see "Parts Derating Requirements and Application Manual" AFSC Pamphlet

800-27. This publication is available from Global Engineering Documents.

Google is your friend.

ehsjr skrev:

Actually it is a good point. A robust design is best implemented with margin from the datasheet limits. The trouble is that one does not always design the circuit optimum in this case. For example if the datasheet limits really are limits - or if the designer of the part has used his/her own derating rules.

In our company we have been designing accordingy to the conservative space derating rules (derated power to 60%, voltage to 80% current to

80%)

For example for a ceramic capacitor this would perhaps be overkill since I have never seen a ceramic cap damaged by running at 100% voltage rating. Anybody else have experience of this?

Regards

Klaus

I've seen 100n MLC's rated at 50V 'burn up' when used for decoupling on 30V supplies. It just happens occasionally. I concluded that it was 'inrush current' as the psu switches on. Polyester 100V ( mylar wound ) types were better but still failed once in a while.

Graham