[sdiy] can a PSU destroy voices chips?

Neil Johnson neil.johnson71 at gmail.com
Tue Nov 19 19:25:25 CET 2013


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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