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Re: [TCML] Ion generator + VDG eats my power supply



Can you explain the concept of parasitic diodes? Yes i can google it but this list is so much more enlightening.

FYI i ordered a replacement in lots of 10. If anyone wants a free quad op-amp let me know (ill pay shipping)

----- Reply message -----
From: "Jim Lux" <jimlux@xxxxxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Subject: [TCML] Ion generator + VDG eats my power supply
Date: Sun, Oct 4, 2015 2:33 PM

On 10/4/15 11:56 AM, msweeney23@xxxxxxxxx wrote:
> It appears the HA17324a quad op amp fried. The Vn(+)2 input pin actually melted right off the IC. I assume that would be an overcurrent situation, possibly caused by some other component failing.
>

Is that a LM324 equivalent? It's just a regular old quad op amp. Almost 
any would probably work.

The data sheet for the 17324 shows a GBW product of about 500kHz.. yep 
it's basically a LM324 except the Renesas part has worse performance.

If you've got some TL074 or TL084s around they would probably work.  If 
you put too high performance an amplifier in there, it might oscillate.

The HA17324a has parasitic diodes from the inputs to the positive 
supply, but doesn't appear to have anything to clamp the inputs going 
negative.
as the data sheet says: " If Input/Output terminals voltage over the 
absolute maximum ratings, there is possibility of mis-operation,
characteristics deterioration and destruction, because
of the current’s flowing to parasitic diode in IC.
The Input/Output terminals are recommended to be protected with the 
clamp circuit which using the diode with
low forward voltage (like schottky barrier diode) when
there is a possibility for the Input/Output terminals
voltage exceeds the absolute maximum ratings. "


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