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I've been looking at these tantalum caps for a coin cell operated BLE device, but I'm a little confused by specified leakage current. The datasheet lists the leakage current at <= 0.003CV uA. With a 470uA cap at 6.0V, my calculated leakage current is 0.003 * 0.000470 * 6.0, which is 0.00000846. The datasheet says that current is in uA.

Is the leakage current really 0.00000846uA? Or is the C (capacitive) value in the equation supposed to be in uF, not F? That would make more sense if the leakage current was 8.46uA, although that seems high for a "low leakage" cap.

And yes, I am well aware of the potential dangers of tantalums. Operating voltage is going to be in the 3.0V - 2.0V range. We have a few other (highly experienced) EEs working on this project, and I'm trying to get up the learning curve on some aspects of datasheet specs.

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  • \$\begingroup\$ For double checking if some values make sense, you can always measure. \$\endgroup\$
    – PlasmaHH
    Jul 15, 2016 at 13:33
  • \$\begingroup\$ @PlasmaHH Unfortunately, I don't have tantalum caps nearby to try out. Good point, though. \$\endgroup\$
    – CHendrix
    Jul 15, 2016 at 13:36
  • \$\begingroup\$ Try another supplier of similar device to see what they say. \$\endgroup\$
    – Andy aka
    Jul 15, 2016 at 13:38
  • \$\begingroup\$ My 0.02, I would assume the same thing as you, they ment either C in uF or really 0.003CV in A. \$\endgroup\$
    – winny
    Jul 15, 2016 at 13:39
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    \$\begingroup\$ A few uA of leakage for a tantalum cap seems realistic. Tantalum have relatively high leakage. Ceramic would have much less, but of course, you can't have such a high capacitance value with ceramic. By the way, are you sure you need such a high capacitance somewhere in a battery-operated device? Seems strange to me. \$\endgroup\$
    – dim
    Jul 15, 2016 at 14:10

1 Answer 1

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The formula from the datasheet is leakage = 0.03CV

If you use the capacitance in Farads, then at 6V you have 84.6uA

Table 1 in the datasheet states the maximum leakage for the 470uF cap at 25C is 89uA.

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    \$\begingroup\$ Unless you have a guarantee of leakage current, it can be very scattered part-to-part. Measuring won't help unless you measure a lot of them. Then you can do a probability curve. \$\endgroup\$ Jul 15, 2016 at 16:18
  • \$\begingroup\$ Wow. Can't believe I missed that table in the datasheet. \$\endgroup\$
    – CHendrix
    Jul 15, 2016 at 16:48

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