[sdiy] can a PSU destroy voices chips?

Barry Klein Barry.L.Klein at wdc.com
Tue Nov 19 21:40:48 CET 2013


A TVS diode would turn into a short if the overvoltage is extended past a few seconds.  We use them in HDD's so if you connect your 5V to 12V or 12V to something higher they short.
There are several voltage choices for them.  However the original purpose was to protect against momentary HV spikes not to act as fuses.  (I did get a patent on doing that though! :-)  )
Remove or replace and the drive works.  But if these CEM parts die if the voltage goes to zero it doesn't help much does it.... - is this the case?
Let us know what you come up with as I'm a MM owner and it is in storage and am scared to turn it on.

Barry


-----Original Message-----
From: synth-diy-bounces at dropmix.xs4all.nl [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Jean-Pierre Desrochers
Sent: Tuesday, November 19, 2013 11:22 AM
To: synth-diy
Subject: Re: [sdiy] can a PSU destroy voices chips?

> PowerOne power supplies
> can be fitted with them, either as an option (OVP12 or OVP24) or as
> standard on the 5V outputs.

Good to know !!!!!




Le 2013-11-19 13:25, Neil Johnson a écrit :
> Hi,
> 
> Jean-Pierre Desrochers wrote:
>> I was speaking about terminal IN shorted to terminal OUT
>> causing the non-regulated high voltage to go at the reg out pin (!!!)
> 
> Ah sorry yes that would cause problems!
> 
>>> Carefully read the datasheet of that device.  The 17.1V is the 
>>> maximum
>>> working voltage.  The clamp voltage for that device is 25.2 volts.
>>> 
>> 
>> You are right on that. Sorry I didn't go that far in the transorb 
>> specs..
>> The thing was to suggest the transorb clamping technique
>> to save supply rails from going above a certain level.
> 
> Transorbs are not really the right device for this kind of thing.
> They are really meant for absorbing transient spikes (hence the name
> "TRANSient abSORBer") from things like lightning strikes or ESD
> shocks.
> 
> What you really want for regulator over-voltage protection is a
> crowbar (typically, zener, SCR, and fuse).  PowerOne power supplies
> can be fitted with them, either as an option (OVP12 or OVP24) or as
> standard on the 5V outputs.
> 
> Neil
> --
> http://www.njohnson.co.uk
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