[sdiy] 2164 overvoltage condition?

[Matthias Herrmann]

Neil Johnson and Oscar Salas did some research and write-up:
http://www.milton.arachsys.com/nj71/index.php?menu=2&submenu=2&subsubmenu=3



From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org] On Behalf Of Quincas Moreira
Sent: Tuesday, June 27, 2017 6:49 AM
To: David G Dixon <dixon at mail.ubc.ca>
Cc: synth-diy mailing list <synth-diy at synth-diy.org>
Subject: Re: [sdiy] 2164 overvoltage condition?

Dave, you're a rock star :)

Incidentally, I've heard there's a common trick with diodes done in most designs to protect the 2164 from frying by getting power on one rail before another (or something like that). Can somebody explain that better to me?

On Mon, Jun 26, 2017 at 11:42 PM, David G Dixon <dixon at mail.ubc.ca<mailto:dixon at mail.ubc.ca>> wrote:
You should also realize that the 2164 is a current amp.  I know that the datasheet says that the absolute maximum voltage of the input is the rail voltage, but one never feeds a voltage source directly to 2164.  One drops the voltage across an input resistor (usual 30k) because the input pin is at virtual ground.  Hence, assuming a +15V supply, the largest current the input pin ever sees is about 500uA.  If the rail is connected directly to the input pin, who knows what the input current is -- possibly enough to fry the chip, I guess.

________________________________
From: Synth-diy [mailto:synth-diy-bounces at synth-diy.org<mailto:synth-diy-bounces at synth-diy.org>] On Behalf Of Sean Ellis
Sent: Monday, June 26, 2017 6:48 PM
To: synth-diy at synth-diy.org<mailto:synth-diy at synth-diy.org>
Subject: [sdiy] 2164 overvoltage condition?

I've been breadboarding a filter and oscillator using a single 2164 and I think I just fried my only 2164 on hand. I have the power supply protected but accidentally put -12 straight into the input of one amp (the control pin was at about 2.5V) and suddenly it died. The datasheet specifies the max ratings to the supply rails so I don't get why it could have (seemingly) destroyed the chip. Could it maybe have caused excessive heat?



-Sean

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--
Quincas Moreira
Test Pilot at VBrazil Modular
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