I have Google searched without luck for the formula ( or even a good rule of thumb ) for how DC leakage current varies with temperature for common electrolytic capacitors - ie the usual 85C and 105C types.
My own testing suggests it is strongly positive and increases by a factor of
2 or more with a temp rise of 20C.Anyone help ?
....... Phil
It doesn't seem to enter into most design guide;lines, or even models.
The old (2004) Rifa app notes ( page 13 - not in new app notes ) there's no formula given, just a table:
temp C mult 40 1 85 5
105 20 125 100RL
Some data here (in the front section)
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
"Spehro Pefhany" "Phil Allison"
Some data here (in the front section)
Worth anyone's time to read.
Just the info in pages 6 to 15 is all.
The " bathtub curve" is a treat !!
...... Phil
rule
There's strong history dependence; after storage, the oxide can perforate, and a quarter hour at max temperature and voltage makes it heal. The 'healing' process generates lots of nonrepeatable leakage current.
So consistent measurement requires a temperature/bias prestress cycle (I've used a curve tracer and hot air blower). After that, the measured leakage might be meaningful . Manufacturer's data on leakage is ... sketchy at best. There aren't even any limits except at 25 C, in the datasheets I see.
"whit3rd" "Phil Allison"
" Manufacturer's data on leakage is ... sketchy at best. There aren't even any limits except at 25 C, in the datasheets I see. "
** The DC leakage figures I see published are ambiguous or just plain wrong - particularly in relation to the temperature.If you apply the formula quoted ( ie 3.sq.rt CV uA) and that is for 25 C - then allow the leakage to rise by a factor of 5 or possibly 10 at max temp of 85 C or 105C - a high voltage cap will be dissipating several watts & EXPLODE.
( note " C " in the above formula is in uF )
....... Phil
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