Tant trauma (again)

Apr 25, 2018 25 Replies

In this case the cap didn't blow fast enough and I did 'take out' a down stream opamp. Geesh one stupid mistake can certainly suck up a lot of time. I will report that I paralleled a bunch of the caps and drove them up to 63 volts. No pops or sizzles.

George H.

A polymer one or dry?

Best regards, Piotr

I use a P-MOSFET on the positive rail in some of my circuits. Negligible voltage drop compared to a diode.

I've experimented with blowing up tants, but some entire reels are tough, and once in a while you get a flimsy one.

Voltage isn't so much the hazard as dV/dT, namely current.

You can slow down an LM317 type reg's output dV/dT with a cap on ADJ, to protect downstream tantalums.

I like polymer aluminums as rail bypasses, but their ESR is too low for some linear and switching regs.

John Larkin Highland Technology, Inc lunatic fringe electronics

Right. I've seen Sprague and Hitachi datasheets even specify a circuit series resistance of one ohm per applied volt - a roundabout way of saying limit peak current to 1A.

I've experienced several shorted supply bypass tants; they are usually quick to find. My trickiest tant failure to find was bypassing a zener and highest current it ever saw was just milliamperes!

piglet

A colleague connectted a 12V (adjustable) wall-wart to a 5V embedded computer. The tranzorb ensured that it ran fine, loading the 7W wall wart down to enough to produce only 5V out. But there was "amperage smell" and on inpecting the circuit the transzorb was misaligned, it had desoldered itself and floating around on it's solder blobs.

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